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Bar Magnet and Gauss Law of Magnetism – Complete Physics Notes
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1. Introduction to Bar Magnet
Original classroom SVG diagram redrawn for Kumar Physics Classes notes. NCERT Class 12 Physics concept flow used as reference.
A bar magnet is a permanent magnet with two poles: north pole and south pole. Magnetic field lines outside the magnet go from north pole to south pole, while inside the magnet they go from south pole to north pole. Therefore magnetic field lines are closed continuous curves.
This closed-loop nature is the most important difference between magnetic field lines and electric field lines. A magnetic field line never starts or ends at an isolated magnetic pole because isolated magnetic monopoles have not been found.
2. Properties of Magnet
Original classroom SVG diagram redrawn for Kumar Physics Classes notes. NCERT Class 12 Physics concept flow used as reference.
Every magnet has two poles.
Isolated magnetic pole does not exist.
Like poles repel and unlike poles attract.
Magnetic field lines never intersect.
Field is stronger near poles.
Broken pieces become complete magnets.
3. Magnetic Pole Strength and Magnetic Moment
Original classroom SVG diagram redrawn for Kumar Physics Classes notes. NCERT Class 12 Physics concept flow used as reference.
Magnetic pole strength is denoted by m. If magnetic length of the magnet is 2l, magnetic moment is the product of pole strength and magnetic length.
Magnetic Moment
M = m × 2lMagnetic moment is a vector directed from south pole to north pole inside the magnet. SI unit is A m².
4. Coulomb's Law in Magnetism
Original classroom SVG diagram redrawn for Kumar Physics Classes notes. NCERT Class 12 Physics concept flow used as reference.
The force between two magnetic poles is analogous to Coulomb force between charges.
Force between magnetic poles
F = (μ₀/4π) × m₁m₂/r²The force is attractive for unlike poles and repulsive for like poles. Magnetic field intensity at a point is force experienced by a unit north pole placed at that point.
Magnetic field intensity
B = F/m5. Magnetic Field Intensity at Axial Point
Original classroom SVG diagram redrawn for Kumar Physics Classes notes. NCERT Class 12 Physics concept flow used as reference.
Let a bar magnet have pole strength m, magnetic length 2l and magnetic moment M = 2ml. Point P lies on the axial line at distance r from the centre O.
1Distance from N pole to P is r - l.
2Distance from S pole to P is r + l.
3Field due to N pole at P is along the axial direction.
4Field due to S pole at P is opposite to the field due to N pole.
5Net field is B_axial = (μ₀/4π)[m/(r-l)² - m/(r+l)²].
6Simplifying the bracket gives 4mrl/(r²-l²)².
7Using M = 2ml, final axial field is obtained.
Axial field
B_axial = (μ₀/4π) × 2Mr/(r²-l²)²Short magnet, r >> l
B_axial = (μ₀/4π) × 2M/r³6. Magnetic Field Intensity at Equatorial Point
Original classroom SVG diagram redrawn for Kumar Physics Classes notes. NCERT Class 12 Physics concept flow used as reference.
At an equatorial point, the distances from north and south poles are equal. Vertical components cancel and horizontal components add opposite to magnetic moment.
1Distance from each pole is √(r²+l²).
2Fields due to two poles are equal in magnitude.
3Their vertical components cancel.
4Their horizontal components add opposite to magnetic moment.
5Use M = 2ml to write final expression.
Equatorial field
B_equatorial = (μ₀/4π) × M/(r²+l²)³ᐟ²Short magnet
B_equatorial = (μ₀/4π) × M/r³Same distance for short magnet
B_axial : B_equatorial = 2 : 17. Torque on Magnetic Dipole in Uniform Magnetic Field
Original classroom SVG diagram redrawn for Kumar Physics Classes notes. NCERT Class 12 Physics concept flow used as reference.
A magnetic dipole in a uniform magnetic field experiences torque. The torque tends to align magnetic moment M with magnetic field B.
Torque
τ = MB sinθVector form
τ = M × BTorque is zero at θ = 0° and θ = 180°. Torque is maximum at θ = 90°.
8. Potential Energy of Magnetic Dipole
Original classroom SVG diagram redrawn for Kumar Physics Classes notes. NCERT Class 12 Physics concept flow used as reference.
Potential energy depends on the angle between magnetic moment and magnetic field.
Potential Energy
U = -MB cosθθ = 0°
Stable equilibrium, U = -MB.
Stable equilibrium, U = -MB.
θ = 90°
U = 0.
U = 0.
θ = 180°
Unstable equilibrium, U = +MB.
Unstable equilibrium, U = +MB.
9. Gauss Law of Magnetism
Original classroom SVG diagram redrawn for Kumar Physics Classes notes. NCERT Class 12 Physics concept flow used as reference.
Gauss law of magnetism states that the net magnetic flux through any closed surface is always zero.
Gauss Law of Magnetism
∮ B · dA = 0This is because magnetic monopoles do not exist. Magnetic field lines form closed loops; as many lines enter a closed surface as leave it.
10. Magnetic Flux
Magnetic flux measures the amount of magnetic field passing through a surface.
Magnetic Flux
ΦB = B A cosθHere B is magnetic field, A is area and θ is the angle between B and area vector. SI unit is weber. For a closed surface in magnetism, net flux is always zero.
11. Important Conceptual Cases
Original classroom SVG diagram redrawn for Kumar Physics Classes notes. NCERT Class 12 Physics concept flow used as reference.
Broken Magnet: Each piece becomes a complete magnet with N and S poles.
Magnetic Monopole: No isolated single magnetic pole has been found.
Magnet through Coil: Induced current opposes motion and causes magnetic damping.
Magnet near Magnet: Attraction or repulsion depends on pole orientation.
Force balances weight: Use F_magnetic = mg.
Horseshoe Magnet: Strong nearly uniform field between poles.
12. Applications of Bar Magnet and Magnetic Field
Compass and magnetic needle
Magnetic sensors
Speakers and electric motors
MRI machines
Magnetic separation
Magnetic storage
Laboratory experiments
Horseshoe magnet applications
13. Common Student Mistakes
Mistake 1Thinking magnetic field lines start and end like electric field lines
Correction: draw the diagram first, identify point type and then choose the formula.
Mistake 2Forgetting field lines are closed loops
Correction: draw the diagram first, identify point type and then choose the formula.
Mistake 3Confusing direction of magnetic moment
Correction: draw the diagram first, identify point type and then choose the formula.
Mistake 4Using axial formula at equatorial point
Correction: draw the diagram first, identify point type and then choose the formula.
Mistake 5Forgetting axial field is twice equatorial field for short magnet
Correction: draw the diagram first, identify point type and then choose the formula.
Mistake 6Confusing pole strength with magnetic moment
Correction: draw the diagram first, identify point type and then choose the formula.
Mistake 7Forgetting M = m × 2l
Correction: draw the diagram first, identify point type and then choose the formula.
Mistake 8Confusing stable and unstable equilibrium
Correction: draw the diagram first, identify point type and then choose the formula.
Mistake 9Wrong use of Gauss law of magnetism
Correction: draw the diagram first, identify point type and then choose the formula.
Mistake 10Thinking magnetic monopole exists after breaking magnet
Correction: draw the diagram first, identify point type and then choose the formula.
14. Exam Question Bank With Solutions
Click any question to open the answer and explanation. MCQs include A/B/C/D options, correct answer and detailed solution.
A. CBSE Board Theory Questions
CBSE Theory Question 1Explain properties of magnetic field lines with formula and diagram wherever required.
Answer: Write the definition, draw a neat labeled diagram, define all symbols, derive the formula step-by-step if derivation is asked, and finish with physical meaning. For properties of magnetic field lines, the key point is to connect the diagram with the final formula and avoid confusing magnetic pole strength m with magnetic moment M.
CBSE Theory Question 2Explain bar magnet as an equivalent solenoid with formula and diagram wherever required.
Answer: Write the definition, draw a neat labeled diagram, define all symbols, derive the formula step-by-step if derivation is asked, and finish with physical meaning. For bar magnet as an equivalent solenoid, the key point is to connect the diagram with the final formula and avoid confusing magnetic pole strength m with magnetic moment M.
CBSE Theory Question 3Explain magnetic moment and pole strength with formula and diagram wherever required.
Answer: Write the definition, draw a neat labeled diagram, define all symbols, derive the formula step-by-step if derivation is asked, and finish with physical meaning. For magnetic moment and pole strength, the key point is to connect the diagram with the final formula and avoid confusing magnetic pole strength m with magnetic moment M.
CBSE Theory Question 4Explain Coulomb law in magnetism with formula and diagram wherever required.
Answer: Write the definition, draw a neat labeled diagram, define all symbols, derive the formula step-by-step if derivation is asked, and finish with physical meaning. For Coulomb law in magnetism, the key point is to connect the diagram with the final formula and avoid confusing magnetic pole strength m with magnetic moment M.
CBSE Theory Question 5Explain axial field due to a bar magnet with formula and diagram wherever required.
Answer: Write the definition, draw a neat labeled diagram, define all symbols, derive the formula step-by-step if derivation is asked, and finish with physical meaning. For axial field due to a bar magnet, the key point is to connect the diagram with the final formula and avoid confusing magnetic pole strength m with magnetic moment M.
CBSE Theory Question 6Explain equatorial field due to a bar magnet with formula and diagram wherever required.
Answer: Write the definition, draw a neat labeled diagram, define all symbols, derive the formula step-by-step if derivation is asked, and finish with physical meaning. For equatorial field due to a bar magnet, the key point is to connect the diagram with the final formula and avoid confusing magnetic pole strength m with magnetic moment M.
CBSE Theory Question 7Explain torque on magnetic dipole with formula and diagram wherever required.
Answer: Write the definition, draw a neat labeled diagram, define all symbols, derive the formula step-by-step if derivation is asked, and finish with physical meaning. For torque on magnetic dipole, the key point is to connect the diagram with the final formula and avoid confusing magnetic pole strength m with magnetic moment M.
CBSE Theory Question 8Explain potential energy of magnetic dipole with formula and diagram wherever required.
Answer: Write the definition, draw a neat labeled diagram, define all symbols, derive the formula step-by-step if derivation is asked, and finish with physical meaning. For potential energy of magnetic dipole, the key point is to connect the diagram with the final formula and avoid confusing magnetic pole strength m with magnetic moment M.
CBSE Theory Question 9Explain Gauss law of magnetism with formula and diagram wherever required.
Answer: Write the definition, draw a neat labeled diagram, define all symbols, derive the formula step-by-step if derivation is asked, and finish with physical meaning. For Gauss law of magnetism, the key point is to connect the diagram with the final formula and avoid confusing magnetic pole strength m with magnetic moment M.
CBSE Theory Question 10Explain broken magnet concept with formula and diagram wherever required.
Answer: Write the definition, draw a neat labeled diagram, define all symbols, derive the formula step-by-step if derivation is asked, and finish with physical meaning. For broken magnet concept, the key point is to connect the diagram with the final formula and avoid confusing magnetic pole strength m with magnetic moment M.
CBSE Theory Question 11Explain properties of magnetic field lines with formula and diagram wherever required.
Answer: Write the definition, draw a neat labeled diagram, define all symbols, derive the formula step-by-step if derivation is asked, and finish with physical meaning. For properties of magnetic field lines, the key point is to connect the diagram with the final formula and avoid confusing magnetic pole strength m with magnetic moment M.
CBSE Theory Question 12Explain bar magnet as an equivalent solenoid with formula and diagram wherever required.
Answer: Write the definition, draw a neat labeled diagram, define all symbols, derive the formula step-by-step if derivation is asked, and finish with physical meaning. For bar magnet as an equivalent solenoid, the key point is to connect the diagram with the final formula and avoid confusing magnetic pole strength m with magnetic moment M.
CBSE Theory Question 13Explain magnetic moment and pole strength with formula and diagram wherever required.
Answer: Write the definition, draw a neat labeled diagram, define all symbols, derive the formula step-by-step if derivation is asked, and finish with physical meaning. For magnetic moment and pole strength, the key point is to connect the diagram with the final formula and avoid confusing magnetic pole strength m with magnetic moment M.
CBSE Theory Question 14Explain Coulomb law in magnetism with formula and diagram wherever required.
Answer: Write the definition, draw a neat labeled diagram, define all symbols, derive the formula step-by-step if derivation is asked, and finish with physical meaning. For Coulomb law in magnetism, the key point is to connect the diagram with the final formula and avoid confusing magnetic pole strength m with magnetic moment M.
CBSE Theory Question 15Explain axial field due to a bar magnet with formula and diagram wherever required.
Answer: Write the definition, draw a neat labeled diagram, define all symbols, derive the formula step-by-step if derivation is asked, and finish with physical meaning. For axial field due to a bar magnet, the key point is to connect the diagram with the final formula and avoid confusing magnetic pole strength m with magnetic moment M.
CBSE Theory Question 16Explain equatorial field due to a bar magnet with formula and diagram wherever required.
Answer: Write the definition, draw a neat labeled diagram, define all symbols, derive the formula step-by-step if derivation is asked, and finish with physical meaning. For equatorial field due to a bar magnet, the key point is to connect the diagram with the final formula and avoid confusing magnetic pole strength m with magnetic moment M.
CBSE Theory Question 17Explain torque on magnetic dipole with formula and diagram wherever required.
Answer: Write the definition, draw a neat labeled diagram, define all symbols, derive the formula step-by-step if derivation is asked, and finish with physical meaning. For torque on magnetic dipole, the key point is to connect the diagram with the final formula and avoid confusing magnetic pole strength m with magnetic moment M.
CBSE Theory Question 18Explain potential energy of magnetic dipole with formula and diagram wherever required.
Answer: Write the definition, draw a neat labeled diagram, define all symbols, derive the formula step-by-step if derivation is asked, and finish with physical meaning. For potential energy of magnetic dipole, the key point is to connect the diagram with the final formula and avoid confusing magnetic pole strength m with magnetic moment M.
CBSE Theory Question 19Explain Gauss law of magnetism with formula and diagram wherever required.
Answer: Write the definition, draw a neat labeled diagram, define all symbols, derive the formula step-by-step if derivation is asked, and finish with physical meaning. For Gauss law of magnetism, the key point is to connect the diagram with the final formula and avoid confusing magnetic pole strength m with magnetic moment M.
CBSE Theory Question 20Explain broken magnet concept with formula and diagram wherever required.
Answer: Write the definition, draw a neat labeled diagram, define all symbols, derive the formula step-by-step if derivation is asked, and finish with physical meaning. For broken magnet concept, the key point is to connect the diagram with the final formula and avoid confusing magnetic pole strength m with magnetic moment M.
CBSE Theory Question 21Explain properties of magnetic field lines with formula and diagram wherever required.
Answer: Write the definition, draw a neat labeled diagram, define all symbols, derive the formula step-by-step if derivation is asked, and finish with physical meaning. For properties of magnetic field lines, the key point is to connect the diagram with the final formula and avoid confusing magnetic pole strength m with magnetic moment M.
CBSE Theory Question 22Explain bar magnet as an equivalent solenoid with formula and diagram wherever required.
Answer: Write the definition, draw a neat labeled diagram, define all symbols, derive the formula step-by-step if derivation is asked, and finish with physical meaning. For bar magnet as an equivalent solenoid, the key point is to connect the diagram with the final formula and avoid confusing magnetic pole strength m with magnetic moment M.
CBSE Theory Question 23Explain magnetic moment and pole strength with formula and diagram wherever required.
Answer: Write the definition, draw a neat labeled diagram, define all symbols, derive the formula step-by-step if derivation is asked, and finish with physical meaning. For magnetic moment and pole strength, the key point is to connect the diagram with the final formula and avoid confusing magnetic pole strength m with magnetic moment M.
CBSE Theory Question 24Explain Coulomb law in magnetism with formula and diagram wherever required.
Answer: Write the definition, draw a neat labeled diagram, define all symbols, derive the formula step-by-step if derivation is asked, and finish with physical meaning. For Coulomb law in magnetism, the key point is to connect the diagram with the final formula and avoid confusing magnetic pole strength m with magnetic moment M.
CBSE Theory Question 25Explain axial field due to a bar magnet with formula and diagram wherever required.
Answer: Write the definition, draw a neat labeled diagram, define all symbols, derive the formula step-by-step if derivation is asked, and finish with physical meaning. For axial field due to a bar magnet, the key point is to connect the diagram with the final formula and avoid confusing magnetic pole strength m with magnetic moment M.
CBSE Theory Question 26Explain equatorial field due to a bar magnet with formula and diagram wherever required.
Answer: Write the definition, draw a neat labeled diagram, define all symbols, derive the formula step-by-step if derivation is asked, and finish with physical meaning. For equatorial field due to a bar magnet, the key point is to connect the diagram with the final formula and avoid confusing magnetic pole strength m with magnetic moment M.
CBSE Theory Question 27Explain torque on magnetic dipole with formula and diagram wherever required.
Answer: Write the definition, draw a neat labeled diagram, define all symbols, derive the formula step-by-step if derivation is asked, and finish with physical meaning. For torque on magnetic dipole, the key point is to connect the diagram with the final formula and avoid confusing magnetic pole strength m with magnetic moment M.
CBSE Theory Question 28Explain potential energy of magnetic dipole with formula and diagram wherever required.
Answer: Write the definition, draw a neat labeled diagram, define all symbols, derive the formula step-by-step if derivation is asked, and finish with physical meaning. For potential energy of magnetic dipole, the key point is to connect the diagram with the final formula and avoid confusing magnetic pole strength m with magnetic moment M.
CBSE Theory Question 29Explain Gauss law of magnetism with formula and diagram wherever required.
Answer: Write the definition, draw a neat labeled diagram, define all symbols, derive the formula step-by-step if derivation is asked, and finish with physical meaning. For Gauss law of magnetism, the key point is to connect the diagram with the final formula and avoid confusing magnetic pole strength m with magnetic moment M.
CBSE Theory Question 30Explain broken magnet concept with formula and diagram wherever required.
Answer: Write the definition, draw a neat labeled diagram, define all symbols, derive the formula step-by-step if derivation is asked, and finish with physical meaning. For broken magnet concept, the key point is to connect the diagram with the final formula and avoid confusing magnetic pole strength m with magnetic moment M.
A. CBSE Board Derivation Questions
CBSE Derivation Question 1Explain properties of magnetic field lines with formula and diagram wherever required.
Answer: Write the definition, draw a neat labeled diagram, define all symbols, derive the formula step-by-step if derivation is asked, and finish with physical meaning. For properties of magnetic field lines, the key point is to connect the diagram with the final formula and avoid confusing magnetic pole strength m with magnetic moment M.
CBSE Derivation Question 2Explain bar magnet as an equivalent solenoid with formula and diagram wherever required.
Answer: Write the definition, draw a neat labeled diagram, define all symbols, derive the formula step-by-step if derivation is asked, and finish with physical meaning. For bar magnet as an equivalent solenoid, the key point is to connect the diagram with the final formula and avoid confusing magnetic pole strength m with magnetic moment M.
CBSE Derivation Question 3Explain magnetic moment and pole strength with formula and diagram wherever required.
Answer: Write the definition, draw a neat labeled diagram, define all symbols, derive the formula step-by-step if derivation is asked, and finish with physical meaning. For magnetic moment and pole strength, the key point is to connect the diagram with the final formula and avoid confusing magnetic pole strength m with magnetic moment M.
CBSE Derivation Question 4Explain Coulomb law in magnetism with formula and diagram wherever required.
Answer: Write the definition, draw a neat labeled diagram, define all symbols, derive the formula step-by-step if derivation is asked, and finish with physical meaning. For Coulomb law in magnetism, the key point is to connect the diagram with the final formula and avoid confusing magnetic pole strength m with magnetic moment M.
CBSE Derivation Question 5Explain axial field due to a bar magnet with formula and diagram wherever required.
Answer: Write the definition, draw a neat labeled diagram, define all symbols, derive the formula step-by-step if derivation is asked, and finish with physical meaning. For axial field due to a bar magnet, the key point is to connect the diagram with the final formula and avoid confusing magnetic pole strength m with magnetic moment M.
CBSE Derivation Question 6Explain equatorial field due to a bar magnet with formula and diagram wherever required.
Answer: Write the definition, draw a neat labeled diagram, define all symbols, derive the formula step-by-step if derivation is asked, and finish with physical meaning. For equatorial field due to a bar magnet, the key point is to connect the diagram with the final formula and avoid confusing magnetic pole strength m with magnetic moment M.
CBSE Derivation Question 7Explain torque on magnetic dipole with formula and diagram wherever required.
Answer: Write the definition, draw a neat labeled diagram, define all symbols, derive the formula step-by-step if derivation is asked, and finish with physical meaning. For torque on magnetic dipole, the key point is to connect the diagram with the final formula and avoid confusing magnetic pole strength m with magnetic moment M.
CBSE Derivation Question 8Explain potential energy of magnetic dipole with formula and diagram wherever required.
Answer: Write the definition, draw a neat labeled diagram, define all symbols, derive the formula step-by-step if derivation is asked, and finish with physical meaning. For potential energy of magnetic dipole, the key point is to connect the diagram with the final formula and avoid confusing magnetic pole strength m with magnetic moment M.
CBSE Derivation Question 9Explain Gauss law of magnetism with formula and diagram wherever required.
Answer: Write the definition, draw a neat labeled diagram, define all symbols, derive the formula step-by-step if derivation is asked, and finish with physical meaning. For Gauss law of magnetism, the key point is to connect the diagram with the final formula and avoid confusing magnetic pole strength m with magnetic moment M.
CBSE Derivation Question 10Explain broken magnet concept with formula and diagram wherever required.
Answer: Write the definition, draw a neat labeled diagram, define all symbols, derive the formula step-by-step if derivation is asked, and finish with physical meaning. For broken magnet concept, the key point is to connect the diagram with the final formula and avoid confusing magnetic pole strength m with magnetic moment M.
CBSE Derivation Question 11Explain properties of magnetic field lines with formula and diagram wherever required.
Answer: Write the definition, draw a neat labeled diagram, define all symbols, derive the formula step-by-step if derivation is asked, and finish with physical meaning. For properties of magnetic field lines, the key point is to connect the diagram with the final formula and avoid confusing magnetic pole strength m with magnetic moment M.
CBSE Derivation Question 12Explain bar magnet as an equivalent solenoid with formula and diagram wherever required.
Answer: Write the definition, draw a neat labeled diagram, define all symbols, derive the formula step-by-step if derivation is asked, and finish with physical meaning. For bar magnet as an equivalent solenoid, the key point is to connect the diagram with the final formula and avoid confusing magnetic pole strength m with magnetic moment M.
CBSE Derivation Question 13Explain magnetic moment and pole strength with formula and diagram wherever required.
Answer: Write the definition, draw a neat labeled diagram, define all symbols, derive the formula step-by-step if derivation is asked, and finish with physical meaning. For magnetic moment and pole strength, the key point is to connect the diagram with the final formula and avoid confusing magnetic pole strength m with magnetic moment M.
CBSE Derivation Question 14Explain Coulomb law in magnetism with formula and diagram wherever required.
Answer: Write the definition, draw a neat labeled diagram, define all symbols, derive the formula step-by-step if derivation is asked, and finish with physical meaning. For Coulomb law in magnetism, the key point is to connect the diagram with the final formula and avoid confusing magnetic pole strength m with magnetic moment M.
CBSE Derivation Question 15Explain axial field due to a bar magnet with formula and diagram wherever required.
Answer: Write the definition, draw a neat labeled diagram, define all symbols, derive the formula step-by-step if derivation is asked, and finish with physical meaning. For axial field due to a bar magnet, the key point is to connect the diagram with the final formula and avoid confusing magnetic pole strength m with magnetic moment M.
CBSE Derivation Question 16Explain equatorial field due to a bar magnet with formula and diagram wherever required.
Answer: Write the definition, draw a neat labeled diagram, define all symbols, derive the formula step-by-step if derivation is asked, and finish with physical meaning. For equatorial field due to a bar magnet, the key point is to connect the diagram with the final formula and avoid confusing magnetic pole strength m with magnetic moment M.
CBSE Derivation Question 17Explain torque on magnetic dipole with formula and diagram wherever required.
Answer: Write the definition, draw a neat labeled diagram, define all symbols, derive the formula step-by-step if derivation is asked, and finish with physical meaning. For torque on magnetic dipole, the key point is to connect the diagram with the final formula and avoid confusing magnetic pole strength m with magnetic moment M.
CBSE Derivation Question 18Explain potential energy of magnetic dipole with formula and diagram wherever required.
Answer: Write the definition, draw a neat labeled diagram, define all symbols, derive the formula step-by-step if derivation is asked, and finish with physical meaning. For potential energy of magnetic dipole, the key point is to connect the diagram with the final formula and avoid confusing magnetic pole strength m with magnetic moment M.
CBSE Derivation Question 19Explain Gauss law of magnetism with formula and diagram wherever required.
Answer: Write the definition, draw a neat labeled diagram, define all symbols, derive the formula step-by-step if derivation is asked, and finish with physical meaning. For Gauss law of magnetism, the key point is to connect the diagram with the final formula and avoid confusing magnetic pole strength m with magnetic moment M.
CBSE Derivation Question 20Explain broken magnet concept with formula and diagram wherever required.
Answer: Write the definition, draw a neat labeled diagram, define all symbols, derive the formula step-by-step if derivation is asked, and finish with physical meaning. For broken magnet concept, the key point is to connect the diagram with the final formula and avoid confusing magnetic pole strength m with magnetic moment M.
A. CBSE Board Numerical Questions
CBSE Numerical Question 1For a short bar magnet, the magnetic field at an axial point and equatorial point at the same distance are in the ratio
A) 1 : 1
B) 2 : 1
C) 1 : 2
D) 4 : 1
Correct Answer: B
Difficulty: Board level
Concept Tested: Axial and equatorial field comparison
Detailed Explanation: For a short magnet, B_axial = (μ₀/4π)(2M/r³) and B_equatorial = (μ₀/4π)(M/r³). Hence ratio is 2:1.
Common trap: Students often choose formula without checking whether the point is axial, equatorial, or a general point.
Difficulty: Board level
Concept Tested: Axial and equatorial field comparison
Detailed Explanation: For a short magnet, B_axial = (μ₀/4π)(2M/r³) and B_equatorial = (μ₀/4π)(M/r³). Hence ratio is 2:1.
Common trap: Students often choose formula without checking whether the point is axial, equatorial, or a general point.
CBSE Numerical Question 2A bar magnet is broken into two equal pieces perpendicular to its length. Which statement is correct?
A) Each piece has only one pole
B) Magnetic monopoles are formed
C) Each piece is a complete magnet
D) Magnetic moment becomes zero
Correct Answer: C
Difficulty: Board level
Concept Tested: Broken magnet
Detailed Explanation: Every broken piece again has north and south poles. Magnetic monopoles are not produced by breaking a magnet.
Common trap: Students often choose formula without checking whether the point is axial, equatorial, or a general point.
Difficulty: Board level
Concept Tested: Broken magnet
Detailed Explanation: Every broken piece again has north and south poles. Magnetic monopoles are not produced by breaking a magnet.
Common trap: Students often choose formula without checking whether the point is axial, equatorial, or a general point.
CBSE Numerical Question 3Net magnetic flux through any closed surface is
A) μ₀ times magnetic pole inside
B) zero
C) BA always
D) infinite for a bar magnet
Correct Answer: B
Difficulty: Board level
Concept Tested: Gauss law of magnetism
Detailed Explanation: Gauss law of magnetism gives ∮B·dA = 0 because magnetic monopoles do not exist.
Common trap: Students often choose formula without checking whether the point is axial, equatorial, or a general point.
Difficulty: Board level
Concept Tested: Gauss law of magnetism
Detailed Explanation: Gauss law of magnetism gives ∮B·dA = 0 because magnetic monopoles do not exist.
Common trap: Students often choose formula without checking whether the point is axial, equatorial, or a general point.
CBSE Numerical Question 4A magnetic dipole is in stable equilibrium when angle between M and B is
A) 0°
B) 90°
C) 180°
D) 270°
Correct Answer: A
Difficulty: Board level
Concept Tested: Magnetic potential energy
Detailed Explanation: Potential energy U = -MB cosθ is minimum at θ = 0°, so equilibrium is stable.
Common trap: Students often choose formula without checking whether the point is axial, equatorial, or a general point.
Difficulty: Board level
Concept Tested: Magnetic potential energy
Detailed Explanation: Potential energy U = -MB cosθ is minimum at θ = 0°, so equilibrium is stable.
Common trap: Students often choose formula without checking whether the point is axial, equatorial, or a general point.
CBSE Numerical Question 5Torque on a magnetic dipole in uniform magnetic field is maximum when θ is
A) 0°
B) 45°
C) 90°
D) 180°
Correct Answer: C
Difficulty: Board level
Concept Tested: Torque on dipole
Detailed Explanation: τ = MB sinθ is maximum when sinθ = 1, i.e. θ = 90°.
Common trap: Students often choose formula without checking whether the point is axial, equatorial, or a general point.
Difficulty: Board level
Concept Tested: Torque on dipole
Detailed Explanation: τ = MB sinθ is maximum when sinθ = 1, i.e. θ = 90°.
Common trap: Students often choose formula without checking whether the point is axial, equatorial, or a general point.
CBSE Numerical Question 6Direction of magnetic moment of a bar magnet is
A) N to S outside the magnet
B) S to N inside the magnet
C) Always downward
D) Opposite to magnetic field lines everywhere
Correct Answer: B
Difficulty: Board level
Concept Tested: Magnetic moment direction
Detailed Explanation: Magnetic moment vector is directed from south pole to north pole inside the magnet.
Common trap: Students often choose formula without checking whether the point is axial, equatorial, or a general point.
Difficulty: Board level
Concept Tested: Magnetic moment direction
Detailed Explanation: Magnetic moment vector is directed from south pole to north pole inside the magnet.
Common trap: Students often choose formula without checking whether the point is axial, equatorial, or a general point.
CBSE Numerical Question 7If distance from a short magnet is doubled, axial magnetic field becomes
A) 1/2
B) 1/4
C) 1/8
D) 1/16
Correct Answer: C
Difficulty: Board level
Concept Tested: Short magnet inverse-cube law
Detailed Explanation: For a short magnet, B_axial ∝ 1/r³. Doubling r makes field 1/8.
Common trap: Students often choose formula without checking whether the point is axial, equatorial, or a general point.
Difficulty: Board level
Concept Tested: Short magnet inverse-cube law
Detailed Explanation: For a short magnet, B_axial ∝ 1/r³. Doubling r makes field 1/8.
Common trap: Students often choose formula without checking whether the point is axial, equatorial, or a general point.
CBSE Numerical Question 8Magnetic field lines never intersect because
A) they are imaginary
B) magnetic field has unique direction at a point
C) monopoles exist
D) field is scalar
Correct Answer: B
Difficulty: Board level
Concept Tested: Properties of magnetic field lines
Detailed Explanation: If two field lines intersect, there would be two directions of magnetic field at the same point, which is impossible.
Common trap: Students often choose formula without checking whether the point is axial, equatorial, or a general point.
Difficulty: Board level
Concept Tested: Properties of magnetic field lines
Detailed Explanation: If two field lines intersect, there would be two directions of magnetic field at the same point, which is impossible.
Common trap: Students often choose formula without checking whether the point is axial, equatorial, or a general point.
CBSE Numerical Question 9For a short bar magnet, the magnetic field at an axial point and equatorial point at the same distance are in the ratio
A) 1 : 1
B) 2 : 1
C) 1 : 2
D) 4 : 1
Correct Answer: B
Difficulty: Board level
Concept Tested: Axial and equatorial field comparison
Detailed Explanation: For a short magnet, B_axial = (μ₀/4π)(2M/r³) and B_equatorial = (μ₀/4π)(M/r³). Hence ratio is 2:1.
Common trap: Students often choose formula without checking whether the point is axial, equatorial, or a general point.
Difficulty: Board level
Concept Tested: Axial and equatorial field comparison
Detailed Explanation: For a short magnet, B_axial = (μ₀/4π)(2M/r³) and B_equatorial = (μ₀/4π)(M/r³). Hence ratio is 2:1.
Common trap: Students often choose formula without checking whether the point is axial, equatorial, or a general point.
CBSE Numerical Question 10A bar magnet is broken into two equal pieces perpendicular to its length. Which statement is correct?
A) Each piece has only one pole
B) Magnetic monopoles are formed
C) Each piece is a complete magnet
D) Magnetic moment becomes zero
Correct Answer: C
Difficulty: Board level
Concept Tested: Broken magnet
Detailed Explanation: Every broken piece again has north and south poles. Magnetic monopoles are not produced by breaking a magnet.
Common trap: Students often choose formula without checking whether the point is axial, equatorial, or a general point.
Difficulty: Board level
Concept Tested: Broken magnet
Detailed Explanation: Every broken piece again has north and south poles. Magnetic monopoles are not produced by breaking a magnet.
Common trap: Students often choose formula without checking whether the point is axial, equatorial, or a general point.
CBSE Numerical Question 11Net magnetic flux through any closed surface is
A) μ₀ times magnetic pole inside
B) zero
C) BA always
D) infinite for a bar magnet
Correct Answer: B
Difficulty: Board level
Concept Tested: Gauss law of magnetism
Detailed Explanation: Gauss law of magnetism gives ∮B·dA = 0 because magnetic monopoles do not exist.
Common trap: Students often choose formula without checking whether the point is axial, equatorial, or a general point.
Difficulty: Board level
Concept Tested: Gauss law of magnetism
Detailed Explanation: Gauss law of magnetism gives ∮B·dA = 0 because magnetic monopoles do not exist.
Common trap: Students often choose formula without checking whether the point is axial, equatorial, or a general point.
CBSE Numerical Question 12A magnetic dipole is in stable equilibrium when angle between M and B is
A) 0°
B) 90°
C) 180°
D) 270°
Correct Answer: A
Difficulty: Board level
Concept Tested: Magnetic potential energy
Detailed Explanation: Potential energy U = -MB cosθ is minimum at θ = 0°, so equilibrium is stable.
Common trap: Students often choose formula without checking whether the point is axial, equatorial, or a general point.
Difficulty: Board level
Concept Tested: Magnetic potential energy
Detailed Explanation: Potential energy U = -MB cosθ is minimum at θ = 0°, so equilibrium is stable.
Common trap: Students often choose formula without checking whether the point is axial, equatorial, or a general point.
CBSE Numerical Question 13Torque on a magnetic dipole in uniform magnetic field is maximum when θ is
A) 0°
B) 45°
C) 90°
D) 180°
Correct Answer: C
Difficulty: Board level
Concept Tested: Torque on dipole
Detailed Explanation: τ = MB sinθ is maximum when sinθ = 1, i.e. θ = 90°.
Common trap: Students often choose formula without checking whether the point is axial, equatorial, or a general point.
Difficulty: Board level
Concept Tested: Torque on dipole
Detailed Explanation: τ = MB sinθ is maximum when sinθ = 1, i.e. θ = 90°.
Common trap: Students often choose formula without checking whether the point is axial, equatorial, or a general point.
CBSE Numerical Question 14Direction of magnetic moment of a bar magnet is
A) N to S outside the magnet
B) S to N inside the magnet
C) Always downward
D) Opposite to magnetic field lines everywhere
Correct Answer: B
Difficulty: Board level
Concept Tested: Magnetic moment direction
Detailed Explanation: Magnetic moment vector is directed from south pole to north pole inside the magnet.
Common trap: Students often choose formula without checking whether the point is axial, equatorial, or a general point.
Difficulty: Board level
Concept Tested: Magnetic moment direction
Detailed Explanation: Magnetic moment vector is directed from south pole to north pole inside the magnet.
Common trap: Students often choose formula without checking whether the point is axial, equatorial, or a general point.
CBSE Numerical Question 15If distance from a short magnet is doubled, axial magnetic field becomes
A) 1/2
B) 1/4
C) 1/8
D) 1/16
Correct Answer: C
Difficulty: Board level
Concept Tested: Short magnet inverse-cube law
Detailed Explanation: For a short magnet, B_axial ∝ 1/r³. Doubling r makes field 1/8.
Common trap: Students often choose formula without checking whether the point is axial, equatorial, or a general point.
Difficulty: Board level
Concept Tested: Short magnet inverse-cube law
Detailed Explanation: For a short magnet, B_axial ∝ 1/r³. Doubling r makes field 1/8.
Common trap: Students often choose formula without checking whether the point is axial, equatorial, or a general point.
CBSE Numerical Question 16Magnetic field lines never intersect because
A) they are imaginary
B) magnetic field has unique direction at a point
C) monopoles exist
D) field is scalar
Correct Answer: B
Difficulty: Board level
Concept Tested: Properties of magnetic field lines
Detailed Explanation: If two field lines intersect, there would be two directions of magnetic field at the same point, which is impossible.
Common trap: Students often choose formula without checking whether the point is axial, equatorial, or a general point.
Difficulty: Board level
Concept Tested: Properties of magnetic field lines
Detailed Explanation: If two field lines intersect, there would be two directions of magnetic field at the same point, which is impossible.
Common trap: Students often choose formula without checking whether the point is axial, equatorial, or a general point.
CBSE Numerical Question 17For a short bar magnet, the magnetic field at an axial point and equatorial point at the same distance are in the ratio
A) 1 : 1
B) 2 : 1
C) 1 : 2
D) 4 : 1
Correct Answer: B
Difficulty: Board level
Concept Tested: Axial and equatorial field comparison
Detailed Explanation: For a short magnet, B_axial = (μ₀/4π)(2M/r³) and B_equatorial = (μ₀/4π)(M/r³). Hence ratio is 2:1.
Common trap: Students often choose formula without checking whether the point is axial, equatorial, or a general point.
Difficulty: Board level
Concept Tested: Axial and equatorial field comparison
Detailed Explanation: For a short magnet, B_axial = (μ₀/4π)(2M/r³) and B_equatorial = (μ₀/4π)(M/r³). Hence ratio is 2:1.
Common trap: Students often choose formula without checking whether the point is axial, equatorial, or a general point.
CBSE Numerical Question 18A bar magnet is broken into two equal pieces perpendicular to its length. Which statement is correct?
A) Each piece has only one pole
B) Magnetic monopoles are formed
C) Each piece is a complete magnet
D) Magnetic moment becomes zero
Correct Answer: C
Difficulty: Board level
Concept Tested: Broken magnet
Detailed Explanation: Every broken piece again has north and south poles. Magnetic monopoles are not produced by breaking a magnet.
Common trap: Students often choose formula without checking whether the point is axial, equatorial, or a general point.
Difficulty: Board level
Concept Tested: Broken magnet
Detailed Explanation: Every broken piece again has north and south poles. Magnetic monopoles are not produced by breaking a magnet.
Common trap: Students often choose formula without checking whether the point is axial, equatorial, or a general point.
CBSE Numerical Question 19Net magnetic flux through any closed surface is
A) μ₀ times magnetic pole inside
B) zero
C) BA always
D) infinite for a bar magnet
Correct Answer: B
Difficulty: Board level
Concept Tested: Gauss law of magnetism
Detailed Explanation: Gauss law of magnetism gives ∮B·dA = 0 because magnetic monopoles do not exist.
Common trap: Students often choose formula without checking whether the point is axial, equatorial, or a general point.
Difficulty: Board level
Concept Tested: Gauss law of magnetism
Detailed Explanation: Gauss law of magnetism gives ∮B·dA = 0 because magnetic monopoles do not exist.
Common trap: Students often choose formula without checking whether the point is axial, equatorial, or a general point.
CBSE Numerical Question 20A magnetic dipole is in stable equilibrium when angle between M and B is
A) 0°
B) 90°
C) 180°
D) 270°
Correct Answer: A
Difficulty: Board level
Concept Tested: Magnetic potential energy
Detailed Explanation: Potential energy U = -MB cosθ is minimum at θ = 0°, so equilibrium is stable.
Common trap: Students often choose formula without checking whether the point is axial, equatorial, or a general point.
Difficulty: Board level
Concept Tested: Magnetic potential energy
Detailed Explanation: Potential energy U = -MB cosθ is minimum at θ = 0°, so equilibrium is stable.
Common trap: Students often choose formula without checking whether the point is axial, equatorial, or a general point.
CBSE Numerical Question 21Torque on a magnetic dipole in uniform magnetic field is maximum when θ is
A) 0°
B) 45°
C) 90°
D) 180°
Correct Answer: C
Difficulty: Board level
Concept Tested: Torque on dipole
Detailed Explanation: τ = MB sinθ is maximum when sinθ = 1, i.e. θ = 90°.
Common trap: Students often choose formula without checking whether the point is axial, equatorial, or a general point.
Difficulty: Board level
Concept Tested: Torque on dipole
Detailed Explanation: τ = MB sinθ is maximum when sinθ = 1, i.e. θ = 90°.
Common trap: Students often choose formula without checking whether the point is axial, equatorial, or a general point.
CBSE Numerical Question 22Direction of magnetic moment of a bar magnet is
A) N to S outside the magnet
B) S to N inside the magnet
C) Always downward
D) Opposite to magnetic field lines everywhere
Correct Answer: B
Difficulty: Board level
Concept Tested: Magnetic moment direction
Detailed Explanation: Magnetic moment vector is directed from south pole to north pole inside the magnet.
Common trap: Students often choose formula without checking whether the point is axial, equatorial, or a general point.
Difficulty: Board level
Concept Tested: Magnetic moment direction
Detailed Explanation: Magnetic moment vector is directed from south pole to north pole inside the magnet.
Common trap: Students often choose formula without checking whether the point is axial, equatorial, or a general point.
CBSE Numerical Question 23If distance from a short magnet is doubled, axial magnetic field becomes
A) 1/2
B) 1/4
C) 1/8
D) 1/16
Correct Answer: C
Difficulty: Board level
Concept Tested: Short magnet inverse-cube law
Detailed Explanation: For a short magnet, B_axial ∝ 1/r³. Doubling r makes field 1/8.
Common trap: Students often choose formula without checking whether the point is axial, equatorial, or a general point.
Difficulty: Board level
Concept Tested: Short magnet inverse-cube law
Detailed Explanation: For a short magnet, B_axial ∝ 1/r³. Doubling r makes field 1/8.
Common trap: Students often choose formula without checking whether the point is axial, equatorial, or a general point.
CBSE Numerical Question 24Magnetic field lines never intersect because
A) they are imaginary
B) magnetic field has unique direction at a point
C) monopoles exist
D) field is scalar
Correct Answer: B
Difficulty: Board level
Concept Tested: Properties of magnetic field lines
Detailed Explanation: If two field lines intersect, there would be two directions of magnetic field at the same point, which is impossible.
Common trap: Students often choose formula without checking whether the point is axial, equatorial, or a general point.
Difficulty: Board level
Concept Tested: Properties of magnetic field lines
Detailed Explanation: If two field lines intersect, there would be two directions of magnetic field at the same point, which is impossible.
Common trap: Students often choose formula without checking whether the point is axial, equatorial, or a general point.
CBSE Numerical Question 25For a short bar magnet, the magnetic field at an axial point and equatorial point at the same distance are in the ratio
A) 1 : 1
B) 2 : 1
C) 1 : 2
D) 4 : 1
Correct Answer: B
Difficulty: Board level
Concept Tested: Axial and equatorial field comparison
Detailed Explanation: For a short magnet, B_axial = (μ₀/4π)(2M/r³) and B_equatorial = (μ₀/4π)(M/r³). Hence ratio is 2:1.
Common trap: Students often choose formula without checking whether the point is axial, equatorial, or a general point.
Difficulty: Board level
Concept Tested: Axial and equatorial field comparison
Detailed Explanation: For a short magnet, B_axial = (μ₀/4π)(2M/r³) and B_equatorial = (μ₀/4π)(M/r³). Hence ratio is 2:1.
Common trap: Students often choose formula without checking whether the point is axial, equatorial, or a general point.
CBSE Numerical Question 26A bar magnet is broken into two equal pieces perpendicular to its length. Which statement is correct?
A) Each piece has only one pole
B) Magnetic monopoles are formed
C) Each piece is a complete magnet
D) Magnetic moment becomes zero
Correct Answer: C
Difficulty: Board level
Concept Tested: Broken magnet
Detailed Explanation: Every broken piece again has north and south poles. Magnetic monopoles are not produced by breaking a magnet.
Common trap: Students often choose formula without checking whether the point is axial, equatorial, or a general point.
Difficulty: Board level
Concept Tested: Broken magnet
Detailed Explanation: Every broken piece again has north and south poles. Magnetic monopoles are not produced by breaking a magnet.
Common trap: Students often choose formula without checking whether the point is axial, equatorial, or a general point.
CBSE Numerical Question 27Net magnetic flux through any closed surface is
A) μ₀ times magnetic pole inside
B) zero
C) BA always
D) infinite for a bar magnet
Correct Answer: B
Difficulty: Board level
Concept Tested: Gauss law of magnetism
Detailed Explanation: Gauss law of magnetism gives ∮B·dA = 0 because magnetic monopoles do not exist.
Common trap: Students often choose formula without checking whether the point is axial, equatorial, or a general point.
Difficulty: Board level
Concept Tested: Gauss law of magnetism
Detailed Explanation: Gauss law of magnetism gives ∮B·dA = 0 because magnetic monopoles do not exist.
Common trap: Students often choose formula without checking whether the point is axial, equatorial, or a general point.
CBSE Numerical Question 28A magnetic dipole is in stable equilibrium when angle between M and B is
A) 0°
B) 90°
C) 180°
D) 270°
Correct Answer: A
Difficulty: Board level
Concept Tested: Magnetic potential energy
Detailed Explanation: Potential energy U = -MB cosθ is minimum at θ = 0°, so equilibrium is stable.
Common trap: Students often choose formula without checking whether the point is axial, equatorial, or a general point.
Difficulty: Board level
Concept Tested: Magnetic potential energy
Detailed Explanation: Potential energy U = -MB cosθ is minimum at θ = 0°, so equilibrium is stable.
Common trap: Students often choose formula without checking whether the point is axial, equatorial, or a general point.
CBSE Numerical Question 29Torque on a magnetic dipole in uniform magnetic field is maximum when θ is
A) 0°
B) 45°
C) 90°
D) 180°
Correct Answer: C
Difficulty: Board level
Concept Tested: Torque on dipole
Detailed Explanation: τ = MB sinθ is maximum when sinθ = 1, i.e. θ = 90°.
Common trap: Students often choose formula without checking whether the point is axial, equatorial, or a general point.
Difficulty: Board level
Concept Tested: Torque on dipole
Detailed Explanation: τ = MB sinθ is maximum when sinθ = 1, i.e. θ = 90°.
Common trap: Students often choose formula without checking whether the point is axial, equatorial, or a general point.
CBSE Numerical Question 30Direction of magnetic moment of a bar magnet is
A) N to S outside the magnet
B) S to N inside the magnet
C) Always downward
D) Opposite to magnetic field lines everywhere
Correct Answer: B
Difficulty: Board level
Concept Tested: Magnetic moment direction
Detailed Explanation: Magnetic moment vector is directed from south pole to north pole inside the magnet.
Common trap: Students often choose formula without checking whether the point is axial, equatorial, or a general point.
Difficulty: Board level
Concept Tested: Magnetic moment direction
Detailed Explanation: Magnetic moment vector is directed from south pole to north pole inside the magnet.
Common trap: Students often choose formula without checking whether the point is axial, equatorial, or a general point.
A. CBSE Case-Study Questions
Case Study 1Case study based on bar magnet field lines.
Scenario: A student observes bar magnet field lines in a school laboratory.
Questions: Identify the field direction, write the relevant formula, explain the physical meaning, and mention one common mistake.
Solution: Use magnetic field line rules, magnetic dipole formulas and Gauss law where required. If the case involves force balance, use F_magnetic = mg and F = (μ₀/4π)m₁m₂/r². If the case involves a dipole, use τ = MB sinθ and U = -MB cosθ.
Questions: Identify the field direction, write the relevant formula, explain the physical meaning, and mention one common mistake.
Solution: Use magnetic field line rules, magnetic dipole formulas and Gauss law where required. If the case involves force balance, use F_magnetic = mg and F = (μ₀/4π)m₁m₂/r². If the case involves a dipole, use τ = MB sinθ and U = -MB cosθ.
Case Study 2Case study based on broken magnet.
Scenario: A student observes broken magnet in a school laboratory.
Questions: Identify the field direction, write the relevant formula, explain the physical meaning, and mention one common mistake.
Solution: Use magnetic field line rules, magnetic dipole formulas and Gauss law where required. If the case involves force balance, use F_magnetic = mg and F = (μ₀/4π)m₁m₂/r². If the case involves a dipole, use τ = MB sinθ and U = -MB cosθ.
Questions: Identify the field direction, write the relevant formula, explain the physical meaning, and mention one common mistake.
Solution: Use magnetic field line rules, magnetic dipole formulas and Gauss law where required. If the case involves force balance, use F_magnetic = mg and F = (μ₀/4π)m₁m₂/r². If the case involves a dipole, use τ = MB sinθ and U = -MB cosθ.
Case Study 3Case study based on compass needle.
Scenario: A student observes compass needle in a school laboratory.
Questions: Identify the field direction, write the relevant formula, explain the physical meaning, and mention one common mistake.
Solution: Use magnetic field line rules, magnetic dipole formulas and Gauss law where required. If the case involves force balance, use F_magnetic = mg and F = (μ₀/4π)m₁m₂/r². If the case involves a dipole, use τ = MB sinθ and U = -MB cosθ.
Questions: Identify the field direction, write the relevant formula, explain the physical meaning, and mention one common mistake.
Solution: Use magnetic field line rules, magnetic dipole formulas and Gauss law where required. If the case involves force balance, use F_magnetic = mg and F = (μ₀/4π)m₁m₂/r². If the case involves a dipole, use τ = MB sinθ and U = -MB cosθ.
Case Study 4Case study based on axial and equatorial fields.
Scenario: A student observes axial and equatorial fields in a school laboratory.
Questions: Identify the field direction, write the relevant formula, explain the physical meaning, and mention one common mistake.
Solution: Use magnetic field line rules, magnetic dipole formulas and Gauss law where required. If the case involves force balance, use F_magnetic = mg and F = (μ₀/4π)m₁m₂/r². If the case involves a dipole, use τ = MB sinθ and U = -MB cosθ.
Questions: Identify the field direction, write the relevant formula, explain the physical meaning, and mention one common mistake.
Solution: Use magnetic field line rules, magnetic dipole formulas and Gauss law where required. If the case involves force balance, use F_magnetic = mg and F = (μ₀/4π)m₁m₂/r². If the case involves a dipole, use τ = MB sinθ and U = -MB cosθ.
Case Study 5Case study based on magnetic dipole in uniform field.
Scenario: A student observes magnetic dipole in uniform field in a school laboratory.
Questions: Identify the field direction, write the relevant formula, explain the physical meaning, and mention one common mistake.
Solution: Use magnetic field line rules, magnetic dipole formulas and Gauss law where required. If the case involves force balance, use F_magnetic = mg and F = (μ₀/4π)m₁m₂/r². If the case involves a dipole, use τ = MB sinθ and U = -MB cosθ.
Questions: Identify the field direction, write the relevant formula, explain the physical meaning, and mention one common mistake.
Solution: Use magnetic field line rules, magnetic dipole formulas and Gauss law where required. If the case involves force balance, use F_magnetic = mg and F = (μ₀/4π)m₁m₂/r². If the case involves a dipole, use τ = MB sinθ and U = -MB cosθ.
Case Study 6Case study based on horseshoe magnet.
Scenario: A student observes horseshoe magnet in a school laboratory.
Questions: Identify the field direction, write the relevant formula, explain the physical meaning, and mention one common mistake.
Solution: Use magnetic field line rules, magnetic dipole formulas and Gauss law where required. If the case involves force balance, use F_magnetic = mg and F = (μ₀/4π)m₁m₂/r². If the case involves a dipole, use τ = MB sinθ and U = -MB cosθ.
Questions: Identify the field direction, write the relevant formula, explain the physical meaning, and mention one common mistake.
Solution: Use magnetic field line rules, magnetic dipole formulas and Gauss law where required. If the case involves force balance, use F_magnetic = mg and F = (μ₀/4π)m₁m₂/r². If the case involves a dipole, use τ = MB sinθ and U = -MB cosθ.
Case Study 7Case study based on Gauss law of magnetism.
Scenario: A student observes Gauss law of magnetism in a school laboratory.
Questions: Identify the field direction, write the relevant formula, explain the physical meaning, and mention one common mistake.
Solution: Use magnetic field line rules, magnetic dipole formulas and Gauss law where required. If the case involves force balance, use F_magnetic = mg and F = (μ₀/4π)m₁m₂/r². If the case involves a dipole, use τ = MB sinθ and U = -MB cosθ.
Questions: Identify the field direction, write the relevant formula, explain the physical meaning, and mention one common mistake.
Solution: Use magnetic field line rules, magnetic dipole formulas and Gauss law where required. If the case involves force balance, use F_magnetic = mg and F = (μ₀/4π)m₁m₂/r². If the case involves a dipole, use τ = MB sinθ and U = -MB cosθ.
Case Study 8Case study based on magnet falling through conducting coil.
Scenario: A student observes magnet falling through conducting coil in a school laboratory.
Questions: Identify the field direction, write the relevant formula, explain the physical meaning, and mention one common mistake.
Solution: Use magnetic field line rules, magnetic dipole formulas and Gauss law where required. If the case involves force balance, use F_magnetic = mg and F = (μ₀/4π)m₁m₂/r². If the case involves a dipole, use τ = MB sinθ and U = -MB cosθ.
Questions: Identify the field direction, write the relevant formula, explain the physical meaning, and mention one common mistake.
Solution: Use magnetic field line rules, magnetic dipole formulas and Gauss law where required. If the case involves force balance, use F_magnetic = mg and F = (μ₀/4π)m₁m₂/r². If the case involves a dipole, use τ = MB sinθ and U = -MB cosθ.
Case Study 9Case study based on magnetic force balancing weight.
Scenario: A student observes magnetic force balancing weight in a school laboratory.
Questions: Identify the field direction, write the relevant formula, explain the physical meaning, and mention one common mistake.
Solution: Use magnetic field line rules, magnetic dipole formulas and Gauss law where required. If the case involves force balance, use F_magnetic = mg and F = (μ₀/4π)m₁m₂/r². If the case involves a dipole, use τ = MB sinθ and U = -MB cosθ.
Questions: Identify the field direction, write the relevant formula, explain the physical meaning, and mention one common mistake.
Solution: Use magnetic field line rules, magnetic dipole formulas and Gauss law where required. If the case involves force balance, use F_magnetic = mg and F = (μ₀/4π)m₁m₂/r². If the case involves a dipole, use τ = MB sinθ and U = -MB cosθ.
Case Study 10Case study based on bar magnet field lines.
Scenario: A student observes bar magnet field lines in a school laboratory.
Questions: Identify the field direction, write the relevant formula, explain the physical meaning, and mention one common mistake.
Solution: Use magnetic field line rules, magnetic dipole formulas and Gauss law where required. If the case involves force balance, use F_magnetic = mg and F = (μ₀/4π)m₁m₂/r². If the case involves a dipole, use τ = MB sinθ and U = -MB cosθ.
Questions: Identify the field direction, write the relevant formula, explain the physical meaning, and mention one common mistake.
Solution: Use magnetic field line rules, magnetic dipole formulas and Gauss law where required. If the case involves force balance, use F_magnetic = mg and F = (μ₀/4π)m₁m₂/r². If the case involves a dipole, use τ = MB sinθ and U = -MB cosθ.
Case Study 11Case study based on broken magnet.
Scenario: A student observes broken magnet in a school laboratory.
Questions: Identify the field direction, write the relevant formula, explain the physical meaning, and mention one common mistake.
Solution: Use magnetic field line rules, magnetic dipole formulas and Gauss law where required. If the case involves force balance, use F_magnetic = mg and F = (μ₀/4π)m₁m₂/r². If the case involves a dipole, use τ = MB sinθ and U = -MB cosθ.
Questions: Identify the field direction, write the relevant formula, explain the physical meaning, and mention one common mistake.
Solution: Use magnetic field line rules, magnetic dipole formulas and Gauss law where required. If the case involves force balance, use F_magnetic = mg and F = (μ₀/4π)m₁m₂/r². If the case involves a dipole, use τ = MB sinθ and U = -MB cosθ.
Case Study 12Case study based on compass needle.
Scenario: A student observes compass needle in a school laboratory.
Questions: Identify the field direction, write the relevant formula, explain the physical meaning, and mention one common mistake.
Solution: Use magnetic field line rules, magnetic dipole formulas and Gauss law where required. If the case involves force balance, use F_magnetic = mg and F = (μ₀/4π)m₁m₂/r². If the case involves a dipole, use τ = MB sinθ and U = -MB cosθ.
Questions: Identify the field direction, write the relevant formula, explain the physical meaning, and mention one common mistake.
Solution: Use magnetic field line rules, magnetic dipole formulas and Gauss law where required. If the case involves force balance, use F_magnetic = mg and F = (μ₀/4π)m₁m₂/r². If the case involves a dipole, use τ = MB sinθ and U = -MB cosθ.
Case Study 13Case study based on axial and equatorial fields.
Scenario: A student observes axial and equatorial fields in a school laboratory.
Questions: Identify the field direction, write the relevant formula, explain the physical meaning, and mention one common mistake.
Solution: Use magnetic field line rules, magnetic dipole formulas and Gauss law where required. If the case involves force balance, use F_magnetic = mg and F = (μ₀/4π)m₁m₂/r². If the case involves a dipole, use τ = MB sinθ and U = -MB cosθ.
Questions: Identify the field direction, write the relevant formula, explain the physical meaning, and mention one common mistake.
Solution: Use magnetic field line rules, magnetic dipole formulas and Gauss law where required. If the case involves force balance, use F_magnetic = mg and F = (μ₀/4π)m₁m₂/r². If the case involves a dipole, use τ = MB sinθ and U = -MB cosθ.
Case Study 14Case study based on magnetic dipole in uniform field.
Scenario: A student observes magnetic dipole in uniform field in a school laboratory.
Questions: Identify the field direction, write the relevant formula, explain the physical meaning, and mention one common mistake.
Solution: Use magnetic field line rules, magnetic dipole formulas and Gauss law where required. If the case involves force balance, use F_magnetic = mg and F = (μ₀/4π)m₁m₂/r². If the case involves a dipole, use τ = MB sinθ and U = -MB cosθ.
Questions: Identify the field direction, write the relevant formula, explain the physical meaning, and mention one common mistake.
Solution: Use magnetic field line rules, magnetic dipole formulas and Gauss law where required. If the case involves force balance, use F_magnetic = mg and F = (μ₀/4π)m₁m₂/r². If the case involves a dipole, use τ = MB sinθ and U = -MB cosθ.
Case Study 15Case study based on horseshoe magnet.
Scenario: A student observes horseshoe magnet in a school laboratory.
Questions: Identify the field direction, write the relevant formula, explain the physical meaning, and mention one common mistake.
Solution: Use magnetic field line rules, magnetic dipole formulas and Gauss law where required. If the case involves force balance, use F_magnetic = mg and F = (μ₀/4π)m₁m₂/r². If the case involves a dipole, use τ = MB sinθ and U = -MB cosθ.
Questions: Identify the field direction, write the relevant formula, explain the physical meaning, and mention one common mistake.
Solution: Use magnetic field line rules, magnetic dipole formulas and Gauss law where required. If the case involves force balance, use F_magnetic = mg and F = (μ₀/4π)m₁m₂/r². If the case involves a dipole, use τ = MB sinθ and U = -MB cosθ.
B. NEET Tough MCQs
NEET Question 1For a short bar magnet, the magnetic field at an axial point and equatorial point at the same distance are in the ratio
A) 1 : 1
B) 2 : 1
C) 1 : 2
D) 4 : 1
Correct Answer: B
Difficulty: Medium-Difficult
Concept Tested: Axial and equatorial field comparison
Detailed Explanation: For a short magnet, B_axial = (μ₀/4π)(2M/r³) and B_equatorial = (μ₀/4π)(M/r³). Hence ratio is 2:1.
Common trap: Students often choose formula without checking whether the point is axial, equatorial, or a general point.
Difficulty: Medium-Difficult
Concept Tested: Axial and equatorial field comparison
Detailed Explanation: For a short magnet, B_axial = (μ₀/4π)(2M/r³) and B_equatorial = (μ₀/4π)(M/r³). Hence ratio is 2:1.
Common trap: Students often choose formula without checking whether the point is axial, equatorial, or a general point.
NEET Question 2A bar magnet is broken into two equal pieces perpendicular to its length. Which statement is correct?
A) Each piece has only one pole
B) Magnetic monopoles are formed
C) Each piece is a complete magnet
D) Magnetic moment becomes zero
Correct Answer: C
Difficulty: Medium-Difficult
Concept Tested: Broken magnet
Detailed Explanation: Every broken piece again has north and south poles. Magnetic monopoles are not produced by breaking a magnet.
Common trap: Students often choose formula without checking whether the point is axial, equatorial, or a general point.
Difficulty: Medium-Difficult
Concept Tested: Broken magnet
Detailed Explanation: Every broken piece again has north and south poles. Magnetic monopoles are not produced by breaking a magnet.
Common trap: Students often choose formula without checking whether the point is axial, equatorial, or a general point.
NEET Question 3Net magnetic flux through any closed surface is
A) μ₀ times magnetic pole inside
B) zero
C) BA always
D) infinite for a bar magnet
Correct Answer: B
Difficulty: Medium-Difficult
Concept Tested: Gauss law of magnetism
Detailed Explanation: Gauss law of magnetism gives ∮B·dA = 0 because magnetic monopoles do not exist.
Common trap: Students often choose formula without checking whether the point is axial, equatorial, or a general point.
Difficulty: Medium-Difficult
Concept Tested: Gauss law of magnetism
Detailed Explanation: Gauss law of magnetism gives ∮B·dA = 0 because magnetic monopoles do not exist.
Common trap: Students often choose formula without checking whether the point is axial, equatorial, or a general point.
NEET Question 4A magnetic dipole is in stable equilibrium when angle between M and B is
A) 0°
B) 90°
C) 180°
D) 270°
Correct Answer: A
Difficulty: Medium-Difficult
Concept Tested: Magnetic potential energy
Detailed Explanation: Potential energy U = -MB cosθ is minimum at θ = 0°, so equilibrium is stable.
Common trap: Students often choose formula without checking whether the point is axial, equatorial, or a general point.
Difficulty: Medium-Difficult
Concept Tested: Magnetic potential energy
Detailed Explanation: Potential energy U = -MB cosθ is minimum at θ = 0°, so equilibrium is stable.
Common trap: Students often choose formula without checking whether the point is axial, equatorial, or a general point.
NEET Question 5Torque on a magnetic dipole in uniform magnetic field is maximum when θ is
A) 0°
B) 45°
C) 90°
D) 180°
Correct Answer: C
Difficulty: Medium-Difficult
Concept Tested: Torque on dipole
Detailed Explanation: τ = MB sinθ is maximum when sinθ = 1, i.e. θ = 90°.
Common trap: Students often choose formula without checking whether the point is axial, equatorial, or a general point.
Difficulty: Medium-Difficult
Concept Tested: Torque on dipole
Detailed Explanation: τ = MB sinθ is maximum when sinθ = 1, i.e. θ = 90°.
Common trap: Students often choose formula without checking whether the point is axial, equatorial, or a general point.
NEET Question 6Direction of magnetic moment of a bar magnet is
A) N to S outside the magnet
B) S to N inside the magnet
C) Always downward
D) Opposite to magnetic field lines everywhere
Correct Answer: B
Difficulty: Medium-Difficult
Concept Tested: Magnetic moment direction
Detailed Explanation: Magnetic moment vector is directed from south pole to north pole inside the magnet.
Common trap: Students often choose formula without checking whether the point is axial, equatorial, or a general point.
Difficulty: Medium-Difficult
Concept Tested: Magnetic moment direction
Detailed Explanation: Magnetic moment vector is directed from south pole to north pole inside the magnet.
Common trap: Students often choose formula without checking whether the point is axial, equatorial, or a general point.
NEET Question 7If distance from a short magnet is doubled, axial magnetic field becomes
A) 1/2
B) 1/4
C) 1/8
D) 1/16
Correct Answer: C
Difficulty: Medium-Difficult
Concept Tested: Short magnet inverse-cube law
Detailed Explanation: For a short magnet, B_axial ∝ 1/r³. Doubling r makes field 1/8.
Common trap: Students often choose formula without checking whether the point is axial, equatorial, or a general point.
Difficulty: Medium-Difficult
Concept Tested: Short magnet inverse-cube law
Detailed Explanation: For a short magnet, B_axial ∝ 1/r³. Doubling r makes field 1/8.
Common trap: Students often choose formula without checking whether the point is axial, equatorial, or a general point.
NEET Question 8Magnetic field lines never intersect because
A) they are imaginary
B) magnetic field has unique direction at a point
C) monopoles exist
D) field is scalar
Correct Answer: B
Difficulty: Medium-Difficult
Concept Tested: Properties of magnetic field lines
Detailed Explanation: If two field lines intersect, there would be two directions of magnetic field at the same point, which is impossible.
Common trap: Students often choose formula without checking whether the point is axial, equatorial, or a general point.
Difficulty: Medium-Difficult
Concept Tested: Properties of magnetic field lines
Detailed Explanation: If two field lines intersect, there would be two directions of magnetic field at the same point, which is impossible.
Common trap: Students often choose formula without checking whether the point is axial, equatorial, or a general point.
NEET Question 9For a short bar magnet, the magnetic field at an axial point and equatorial point at the same distance are in the ratio
A) 1 : 1
B) 2 : 1
C) 1 : 2
D) 4 : 1
Correct Answer: B
Difficulty: Medium-Difficult
Concept Tested: Axial and equatorial field comparison
Detailed Explanation: For a short magnet, B_axial = (μ₀/4π)(2M/r³) and B_equatorial = (μ₀/4π)(M/r³). Hence ratio is 2:1.
Common trap: Students often choose formula without checking whether the point is axial, equatorial, or a general point.
Difficulty: Medium-Difficult
Concept Tested: Axial and equatorial field comparison
Detailed Explanation: For a short magnet, B_axial = (μ₀/4π)(2M/r³) and B_equatorial = (μ₀/4π)(M/r³). Hence ratio is 2:1.
Common trap: Students often choose formula without checking whether the point is axial, equatorial, or a general point.
NEET Question 10A bar magnet is broken into two equal pieces perpendicular to its length. Which statement is correct?
A) Each piece has only one pole
B) Magnetic monopoles are formed
C) Each piece is a complete magnet
D) Magnetic moment becomes zero
Correct Answer: C
Difficulty: Medium-Difficult
Concept Tested: Broken magnet
Detailed Explanation: Every broken piece again has north and south poles. Magnetic monopoles are not produced by breaking a magnet.
Common trap: Students often choose formula without checking whether the point is axial, equatorial, or a general point.
Difficulty: Medium-Difficult
Concept Tested: Broken magnet
Detailed Explanation: Every broken piece again has north and south poles. Magnetic monopoles are not produced by breaking a magnet.
Common trap: Students often choose formula without checking whether the point is axial, equatorial, or a general point.
NEET Question 11Net magnetic flux through any closed surface is
A) μ₀ times magnetic pole inside
B) zero
C) BA always
D) infinite for a bar magnet
Correct Answer: B
Difficulty: Medium-Difficult
Concept Tested: Gauss law of magnetism
Detailed Explanation: Gauss law of magnetism gives ∮B·dA = 0 because magnetic monopoles do not exist.
Common trap: Students often choose formula without checking whether the point is axial, equatorial, or a general point.
Difficulty: Medium-Difficult
Concept Tested: Gauss law of magnetism
Detailed Explanation: Gauss law of magnetism gives ∮B·dA = 0 because magnetic monopoles do not exist.
Common trap: Students often choose formula without checking whether the point is axial, equatorial, or a general point.
NEET Question 12A magnetic dipole is in stable equilibrium when angle between M and B is
A) 0°
B) 90°
C) 180°
D) 270°
Correct Answer: A
Difficulty: Medium-Difficult
Concept Tested: Magnetic potential energy
Detailed Explanation: Potential energy U = -MB cosθ is minimum at θ = 0°, so equilibrium is stable.
Common trap: Students often choose formula without checking whether the point is axial, equatorial, or a general point.
Difficulty: Medium-Difficult
Concept Tested: Magnetic potential energy
Detailed Explanation: Potential energy U = -MB cosθ is minimum at θ = 0°, so equilibrium is stable.
Common trap: Students often choose formula without checking whether the point is axial, equatorial, or a general point.
NEET Question 13Torque on a magnetic dipole in uniform magnetic field is maximum when θ is
A) 0°
B) 45°
C) 90°
D) 180°
Correct Answer: C
Difficulty: Medium-Difficult
Concept Tested: Torque on dipole
Detailed Explanation: τ = MB sinθ is maximum when sinθ = 1, i.e. θ = 90°.
Common trap: Students often choose formula without checking whether the point is axial, equatorial, or a general point.
Difficulty: Medium-Difficult
Concept Tested: Torque on dipole
Detailed Explanation: τ = MB sinθ is maximum when sinθ = 1, i.e. θ = 90°.
Common trap: Students often choose formula without checking whether the point is axial, equatorial, or a general point.
NEET Question 14Direction of magnetic moment of a bar magnet is
A) N to S outside the magnet
B) S to N inside the magnet
C) Always downward
D) Opposite to magnetic field lines everywhere
Correct Answer: B
Difficulty: Medium-Difficult
Concept Tested: Magnetic moment direction
Detailed Explanation: Magnetic moment vector is directed from south pole to north pole inside the magnet.
Common trap: Students often choose formula without checking whether the point is axial, equatorial, or a general point.
Difficulty: Medium-Difficult
Concept Tested: Magnetic moment direction
Detailed Explanation: Magnetic moment vector is directed from south pole to north pole inside the magnet.
Common trap: Students often choose formula without checking whether the point is axial, equatorial, or a general point.
NEET Question 15If distance from a short magnet is doubled, axial magnetic field becomes
A) 1/2
B) 1/4
C) 1/8
D) 1/16
Correct Answer: C
Difficulty: Medium-Difficult
Concept Tested: Short magnet inverse-cube law
Detailed Explanation: For a short magnet, B_axial ∝ 1/r³. Doubling r makes field 1/8.
Common trap: Students often choose formula without checking whether the point is axial, equatorial, or a general point.
Difficulty: Medium-Difficult
Concept Tested: Short magnet inverse-cube law
Detailed Explanation: For a short magnet, B_axial ∝ 1/r³. Doubling r makes field 1/8.
Common trap: Students often choose formula without checking whether the point is axial, equatorial, or a general point.
NEET Question 16Magnetic field lines never intersect because
A) they are imaginary
B) magnetic field has unique direction at a point
C) monopoles exist
D) field is scalar
Correct Answer: B
Difficulty: Medium-Difficult
Concept Tested: Properties of magnetic field lines
Detailed Explanation: If two field lines intersect, there would be two directions of magnetic field at the same point, which is impossible.
Common trap: Students often choose formula without checking whether the point is axial, equatorial, or a general point.
Difficulty: Medium-Difficult
Concept Tested: Properties of magnetic field lines
Detailed Explanation: If two field lines intersect, there would be two directions of magnetic field at the same point, which is impossible.
Common trap: Students often choose formula without checking whether the point is axial, equatorial, or a general point.
NEET Question 17For a short bar magnet, the magnetic field at an axial point and equatorial point at the same distance are in the ratio
A) 1 : 1
B) 2 : 1
C) 1 : 2
D) 4 : 1
Correct Answer: B
Difficulty: Medium-Difficult
Concept Tested: Axial and equatorial field comparison
Detailed Explanation: For a short magnet, B_axial = (μ₀/4π)(2M/r³) and B_equatorial = (μ₀/4π)(M/r³). Hence ratio is 2:1.
Common trap: Students often choose formula without checking whether the point is axial, equatorial, or a general point.
Difficulty: Medium-Difficult
Concept Tested: Axial and equatorial field comparison
Detailed Explanation: For a short magnet, B_axial = (μ₀/4π)(2M/r³) and B_equatorial = (μ₀/4π)(M/r³). Hence ratio is 2:1.
Common trap: Students often choose formula without checking whether the point is axial, equatorial, or a general point.
NEET Question 18A bar magnet is broken into two equal pieces perpendicular to its length. Which statement is correct?
A) Each piece has only one pole
B) Magnetic monopoles are formed
C) Each piece is a complete magnet
D) Magnetic moment becomes zero
Correct Answer: C
Difficulty: Medium-Difficult
Concept Tested: Broken magnet
Detailed Explanation: Every broken piece again has north and south poles. Magnetic monopoles are not produced by breaking a magnet.
Common trap: Students often choose formula without checking whether the point is axial, equatorial, or a general point.
Difficulty: Medium-Difficult
Concept Tested: Broken magnet
Detailed Explanation: Every broken piece again has north and south poles. Magnetic monopoles are not produced by breaking a magnet.
Common trap: Students often choose formula without checking whether the point is axial, equatorial, or a general point.
NEET Question 19Net magnetic flux through any closed surface is
A) μ₀ times magnetic pole inside
B) zero
C) BA always
D) infinite for a bar magnet
Correct Answer: B
Difficulty: Medium-Difficult
Concept Tested: Gauss law of magnetism
Detailed Explanation: Gauss law of magnetism gives ∮B·dA = 0 because magnetic monopoles do not exist.
Common trap: Students often choose formula without checking whether the point is axial, equatorial, or a general point.
Difficulty: Medium-Difficult
Concept Tested: Gauss law of magnetism
Detailed Explanation: Gauss law of magnetism gives ∮B·dA = 0 because magnetic monopoles do not exist.
Common trap: Students often choose formula without checking whether the point is axial, equatorial, or a general point.
NEET Question 20A magnetic dipole is in stable equilibrium when angle between M and B is
A) 0°
B) 90°
C) 180°
D) 270°
Correct Answer: A
Difficulty: Medium-Difficult
Concept Tested: Magnetic potential energy
Detailed Explanation: Potential energy U = -MB cosθ is minimum at θ = 0°, so equilibrium is stable.
Common trap: Students often choose formula without checking whether the point is axial, equatorial, or a general point.
Difficulty: Medium-Difficult
Concept Tested: Magnetic potential energy
Detailed Explanation: Potential energy U = -MB cosθ is minimum at θ = 0°, so equilibrium is stable.
Common trap: Students often choose formula without checking whether the point is axial, equatorial, or a general point.
NEET Question 21Torque on a magnetic dipole in uniform magnetic field is maximum when θ is
A) 0°
B) 45°
C) 90°
D) 180°
Correct Answer: C
Difficulty: Medium-Difficult
Concept Tested: Torque on dipole
Detailed Explanation: τ = MB sinθ is maximum when sinθ = 1, i.e. θ = 90°.
Common trap: Students often choose formula without checking whether the point is axial, equatorial, or a general point.
Difficulty: Medium-Difficult
Concept Tested: Torque on dipole
Detailed Explanation: τ = MB sinθ is maximum when sinθ = 1, i.e. θ = 90°.
Common trap: Students often choose formula without checking whether the point is axial, equatorial, or a general point.
NEET Question 22Direction of magnetic moment of a bar magnet is
A) N to S outside the magnet
B) S to N inside the magnet
C) Always downward
D) Opposite to magnetic field lines everywhere
Correct Answer: B
Difficulty: Medium-Difficult
Concept Tested: Magnetic moment direction
Detailed Explanation: Magnetic moment vector is directed from south pole to north pole inside the magnet.
Common trap: Students often choose formula without checking whether the point is axial, equatorial, or a general point.
Difficulty: Medium-Difficult
Concept Tested: Magnetic moment direction
Detailed Explanation: Magnetic moment vector is directed from south pole to north pole inside the magnet.
Common trap: Students often choose formula without checking whether the point is axial, equatorial, or a general point.
NEET Question 23If distance from a short magnet is doubled, axial magnetic field becomes
A) 1/2
B) 1/4
C) 1/8
D) 1/16
Correct Answer: C
Difficulty: Medium-Difficult
Concept Tested: Short magnet inverse-cube law
Detailed Explanation: For a short magnet, B_axial ∝ 1/r³. Doubling r makes field 1/8.
Common trap: Students often choose formula without checking whether the point is axial, equatorial, or a general point.
Difficulty: Medium-Difficult
Concept Tested: Short magnet inverse-cube law
Detailed Explanation: For a short magnet, B_axial ∝ 1/r³. Doubling r makes field 1/8.
Common trap: Students often choose formula without checking whether the point is axial, equatorial, or a general point.
NEET Question 24Magnetic field lines never intersect because
A) they are imaginary
B) magnetic field has unique direction at a point
C) monopoles exist
D) field is scalar
Correct Answer: B
Difficulty: Medium-Difficult
Concept Tested: Properties of magnetic field lines
Detailed Explanation: If two field lines intersect, there would be two directions of magnetic field at the same point, which is impossible.
Common trap: Students often choose formula without checking whether the point is axial, equatorial, or a general point.
Difficulty: Medium-Difficult
Concept Tested: Properties of magnetic field lines
Detailed Explanation: If two field lines intersect, there would be two directions of magnetic field at the same point, which is impossible.
Common trap: Students often choose formula without checking whether the point is axial, equatorial, or a general point.
NEET Question 25For a short bar magnet, the magnetic field at an axial point and equatorial point at the same distance are in the ratio
A) 1 : 1
B) 2 : 1
C) 1 : 2
D) 4 : 1
Correct Answer: B
Difficulty: Medium-Difficult
Concept Tested: Axial and equatorial field comparison
Detailed Explanation: For a short magnet, B_axial = (μ₀/4π)(2M/r³) and B_equatorial = (μ₀/4π)(M/r³). Hence ratio is 2:1.
Common trap: Students often choose formula without checking whether the point is axial, equatorial, or a general point.
Difficulty: Medium-Difficult
Concept Tested: Axial and equatorial field comparison
Detailed Explanation: For a short magnet, B_axial = (μ₀/4π)(2M/r³) and B_equatorial = (μ₀/4π)(M/r³). Hence ratio is 2:1.
Common trap: Students often choose formula without checking whether the point is axial, equatorial, or a general point.
NEET Question 26A bar magnet is broken into two equal pieces perpendicular to its length. Which statement is correct?
A) Each piece has only one pole
B) Magnetic monopoles are formed
C) Each piece is a complete magnet
D) Magnetic moment becomes zero
Correct Answer: C
Difficulty: Medium-Difficult
Concept Tested: Broken magnet
Detailed Explanation: Every broken piece again has north and south poles. Magnetic monopoles are not produced by breaking a magnet.
Common trap: Students often choose formula without checking whether the point is axial, equatorial, or a general point.
Difficulty: Medium-Difficult
Concept Tested: Broken magnet
Detailed Explanation: Every broken piece again has north and south poles. Magnetic monopoles are not produced by breaking a magnet.
Common trap: Students often choose formula without checking whether the point is axial, equatorial, or a general point.
NEET Question 27Net magnetic flux through any closed surface is
A) μ₀ times magnetic pole inside
B) zero
C) BA always
D) infinite for a bar magnet
Correct Answer: B
Difficulty: Medium-Difficult
Concept Tested: Gauss law of magnetism
Detailed Explanation: Gauss law of magnetism gives ∮B·dA = 0 because magnetic monopoles do not exist.
Common trap: Students often choose formula without checking whether the point is axial, equatorial, or a general point.
Difficulty: Medium-Difficult
Concept Tested: Gauss law of magnetism
Detailed Explanation: Gauss law of magnetism gives ∮B·dA = 0 because magnetic monopoles do not exist.
Common trap: Students often choose formula without checking whether the point is axial, equatorial, or a general point.
NEET Question 28A magnetic dipole is in stable equilibrium when angle between M and B is
A) 0°
B) 90°
C) 180°
D) 270°
Correct Answer: A
Difficulty: Medium-Difficult
Concept Tested: Magnetic potential energy
Detailed Explanation: Potential energy U = -MB cosθ is minimum at θ = 0°, so equilibrium is stable.
Common trap: Students often choose formula without checking whether the point is axial, equatorial, or a general point.
Difficulty: Medium-Difficult
Concept Tested: Magnetic potential energy
Detailed Explanation: Potential energy U = -MB cosθ is minimum at θ = 0°, so equilibrium is stable.
Common trap: Students often choose formula without checking whether the point is axial, equatorial, or a general point.
NEET Question 29Torque on a magnetic dipole in uniform magnetic field is maximum when θ is
A) 0°
B) 45°
C) 90°
D) 180°
Correct Answer: C
Difficulty: Medium-Difficult
Concept Tested: Torque on dipole
Detailed Explanation: τ = MB sinθ is maximum when sinθ = 1, i.e. θ = 90°.
Common trap: Students often choose formula without checking whether the point is axial, equatorial, or a general point.
Difficulty: Medium-Difficult
Concept Tested: Torque on dipole
Detailed Explanation: τ = MB sinθ is maximum when sinθ = 1, i.e. θ = 90°.
Common trap: Students often choose formula without checking whether the point is axial, equatorial, or a general point.
NEET Question 30Direction of magnetic moment of a bar magnet is
A) N to S outside the magnet
B) S to N inside the magnet
C) Always downward
D) Opposite to magnetic field lines everywhere
Correct Answer: B
Difficulty: Medium-Difficult
Concept Tested: Magnetic moment direction
Detailed Explanation: Magnetic moment vector is directed from south pole to north pole inside the magnet.
Common trap: Students often choose formula without checking whether the point is axial, equatorial, or a general point.
Difficulty: Medium-Difficult
Concept Tested: Magnetic moment direction
Detailed Explanation: Magnetic moment vector is directed from south pole to north pole inside the magnet.
Common trap: Students often choose formula without checking whether the point is axial, equatorial, or a general point.
NEET Question 31If distance from a short magnet is doubled, axial magnetic field becomes
A) 1/2
B) 1/4
C) 1/8
D) 1/16
Correct Answer: C
Difficulty: Medium-Difficult
Concept Tested: Short magnet inverse-cube law
Detailed Explanation: For a short magnet, B_axial ∝ 1/r³. Doubling r makes field 1/8.
Common trap: Students often choose formula without checking whether the point is axial, equatorial, or a general point.
Difficulty: Medium-Difficult
Concept Tested: Short magnet inverse-cube law
Detailed Explanation: For a short magnet, B_axial ∝ 1/r³. Doubling r makes field 1/8.
Common trap: Students often choose formula without checking whether the point is axial, equatorial, or a general point.
NEET Question 32Magnetic field lines never intersect because
A) they are imaginary
B) magnetic field has unique direction at a point
C) monopoles exist
D) field is scalar
Correct Answer: B
Difficulty: Medium-Difficult
Concept Tested: Properties of magnetic field lines
Detailed Explanation: If two field lines intersect, there would be two directions of magnetic field at the same point, which is impossible.
Common trap: Students often choose formula without checking whether the point is axial, equatorial, or a general point.
Difficulty: Medium-Difficult
Concept Tested: Properties of magnetic field lines
Detailed Explanation: If two field lines intersect, there would be two directions of magnetic field at the same point, which is impossible.
Common trap: Students often choose formula without checking whether the point is axial, equatorial, or a general point.
NEET Question 33For a short bar magnet, the magnetic field at an axial point and equatorial point at the same distance are in the ratio
A) 1 : 1
B) 2 : 1
C) 1 : 2
D) 4 : 1
Correct Answer: B
Difficulty: Medium-Difficult
Concept Tested: Axial and equatorial field comparison
Detailed Explanation: For a short magnet, B_axial = (μ₀/4π)(2M/r³) and B_equatorial = (μ₀/4π)(M/r³). Hence ratio is 2:1.
Common trap: Students often choose formula without checking whether the point is axial, equatorial, or a general point.
Difficulty: Medium-Difficult
Concept Tested: Axial and equatorial field comparison
Detailed Explanation: For a short magnet, B_axial = (μ₀/4π)(2M/r³) and B_equatorial = (μ₀/4π)(M/r³). Hence ratio is 2:1.
Common trap: Students often choose formula without checking whether the point is axial, equatorial, or a general point.
NEET Question 34A bar magnet is broken into two equal pieces perpendicular to its length. Which statement is correct?
A) Each piece has only one pole
B) Magnetic monopoles are formed
C) Each piece is a complete magnet
D) Magnetic moment becomes zero
Correct Answer: C
Difficulty: Medium-Difficult
Concept Tested: Broken magnet
Detailed Explanation: Every broken piece again has north and south poles. Magnetic monopoles are not produced by breaking a magnet.
Common trap: Students often choose formula without checking whether the point is axial, equatorial, or a general point.
Difficulty: Medium-Difficult
Concept Tested: Broken magnet
Detailed Explanation: Every broken piece again has north and south poles. Magnetic monopoles are not produced by breaking a magnet.
Common trap: Students often choose formula without checking whether the point is axial, equatorial, or a general point.
NEET Question 35Net magnetic flux through any closed surface is
A) μ₀ times magnetic pole inside
B) zero
C) BA always
D) infinite for a bar magnet
Correct Answer: B
Difficulty: Medium-Difficult
Concept Tested: Gauss law of magnetism
Detailed Explanation: Gauss law of magnetism gives ∮B·dA = 0 because magnetic monopoles do not exist.
Common trap: Students often choose formula without checking whether the point is axial, equatorial, or a general point.
Difficulty: Medium-Difficult
Concept Tested: Gauss law of magnetism
Detailed Explanation: Gauss law of magnetism gives ∮B·dA = 0 because magnetic monopoles do not exist.
Common trap: Students often choose formula without checking whether the point is axial, equatorial, or a general point.
NEET Question 36A magnetic dipole is in stable equilibrium when angle between M and B is
A) 0°
B) 90°
C) 180°
D) 270°
Correct Answer: A
Difficulty: Medium-Difficult
Concept Tested: Magnetic potential energy
Detailed Explanation: Potential energy U = -MB cosθ is minimum at θ = 0°, so equilibrium is stable.
Common trap: Students often choose formula without checking whether the point is axial, equatorial, or a general point.
Difficulty: Medium-Difficult
Concept Tested: Magnetic potential energy
Detailed Explanation: Potential energy U = -MB cosθ is minimum at θ = 0°, so equilibrium is stable.
Common trap: Students often choose formula without checking whether the point is axial, equatorial, or a general point.
NEET Question 37Torque on a magnetic dipole in uniform magnetic field is maximum when θ is
A) 0°
B) 45°
C) 90°
D) 180°
Correct Answer: C
Difficulty: Medium-Difficult
Concept Tested: Torque on dipole
Detailed Explanation: τ = MB sinθ is maximum when sinθ = 1, i.e. θ = 90°.
Common trap: Students often choose formula without checking whether the point is axial, equatorial, or a general point.
Difficulty: Medium-Difficult
Concept Tested: Torque on dipole
Detailed Explanation: τ = MB sinθ is maximum when sinθ = 1, i.e. θ = 90°.
Common trap: Students often choose formula without checking whether the point is axial, equatorial, or a general point.
NEET Question 38Direction of magnetic moment of a bar magnet is
A) N to S outside the magnet
B) S to N inside the magnet
C) Always downward
D) Opposite to magnetic field lines everywhere
Correct Answer: B
Difficulty: Medium-Difficult
Concept Tested: Magnetic moment direction
Detailed Explanation: Magnetic moment vector is directed from south pole to north pole inside the magnet.
Common trap: Students often choose formula without checking whether the point is axial, equatorial, or a general point.
Difficulty: Medium-Difficult
Concept Tested: Magnetic moment direction
Detailed Explanation: Magnetic moment vector is directed from south pole to north pole inside the magnet.
Common trap: Students often choose formula without checking whether the point is axial, equatorial, or a general point.
NEET Question 39If distance from a short magnet is doubled, axial magnetic field becomes
A) 1/2
B) 1/4
C) 1/8
D) 1/16
Correct Answer: C
Difficulty: Medium-Difficult
Concept Tested: Short magnet inverse-cube law
Detailed Explanation: For a short magnet, B_axial ∝ 1/r³. Doubling r makes field 1/8.
Common trap: Students often choose formula without checking whether the point is axial, equatorial, or a general point.
Difficulty: Medium-Difficult
Concept Tested: Short magnet inverse-cube law
Detailed Explanation: For a short magnet, B_axial ∝ 1/r³. Doubling r makes field 1/8.
Common trap: Students often choose formula without checking whether the point is axial, equatorial, or a general point.
NEET Question 40Magnetic field lines never intersect because
A) they are imaginary
B) magnetic field has unique direction at a point
C) monopoles exist
D) field is scalar
Correct Answer: B
Difficulty: Medium-Difficult
Concept Tested: Properties of magnetic field lines
Detailed Explanation: If two field lines intersect, there would be two directions of magnetic field at the same point, which is impossible.
Common trap: Students often choose formula without checking whether the point is axial, equatorial, or a general point.
Difficulty: Medium-Difficult
Concept Tested: Properties of magnetic field lines
Detailed Explanation: If two field lines intersect, there would be two directions of magnetic field at the same point, which is impossible.
Common trap: Students often choose formula without checking whether the point is axial, equatorial, or a general point.
NEET Question 41For a short bar magnet, the magnetic field at an axial point and equatorial point at the same distance are in the ratio
A) 1 : 1
B) 2 : 1
C) 1 : 2
D) 4 : 1
Correct Answer: B
Difficulty: Medium-Difficult
Concept Tested: Axial and equatorial field comparison
Detailed Explanation: For a short magnet, B_axial = (μ₀/4π)(2M/r³) and B_equatorial = (μ₀/4π)(M/r³). Hence ratio is 2:1.
Common trap: Students often choose formula without checking whether the point is axial, equatorial, or a general point.
Difficulty: Medium-Difficult
Concept Tested: Axial and equatorial field comparison
Detailed Explanation: For a short magnet, B_axial = (μ₀/4π)(2M/r³) and B_equatorial = (μ₀/4π)(M/r³). Hence ratio is 2:1.
Common trap: Students often choose formula without checking whether the point is axial, equatorial, or a general point.
NEET Question 42A bar magnet is broken into two equal pieces perpendicular to its length. Which statement is correct?
A) Each piece has only one pole
B) Magnetic monopoles are formed
C) Each piece is a complete magnet
D) Magnetic moment becomes zero
Correct Answer: C
Difficulty: Medium-Difficult
Concept Tested: Broken magnet
Detailed Explanation: Every broken piece again has north and south poles. Magnetic monopoles are not produced by breaking a magnet.
Common trap: Students often choose formula without checking whether the point is axial, equatorial, or a general point.
Difficulty: Medium-Difficult
Concept Tested: Broken magnet
Detailed Explanation: Every broken piece again has north and south poles. Magnetic monopoles are not produced by breaking a magnet.
Common trap: Students often choose formula without checking whether the point is axial, equatorial, or a general point.
NEET Question 43Net magnetic flux through any closed surface is
A) μ₀ times magnetic pole inside
B) zero
C) BA always
D) infinite for a bar magnet
Correct Answer: B
Difficulty: Medium-Difficult
Concept Tested: Gauss law of magnetism
Detailed Explanation: Gauss law of magnetism gives ∮B·dA = 0 because magnetic monopoles do not exist.
Common trap: Students often choose formula without checking whether the point is axial, equatorial, or a general point.
Difficulty: Medium-Difficult
Concept Tested: Gauss law of magnetism
Detailed Explanation: Gauss law of magnetism gives ∮B·dA = 0 because magnetic monopoles do not exist.
Common trap: Students often choose formula without checking whether the point is axial, equatorial, or a general point.
NEET Question 44A magnetic dipole is in stable equilibrium when angle between M and B is
A) 0°
B) 90°
C) 180°
D) 270°
Correct Answer: A
Difficulty: Medium-Difficult
Concept Tested: Magnetic potential energy
Detailed Explanation: Potential energy U = -MB cosθ is minimum at θ = 0°, so equilibrium is stable.
Common trap: Students often choose formula without checking whether the point is axial, equatorial, or a general point.
Difficulty: Medium-Difficult
Concept Tested: Magnetic potential energy
Detailed Explanation: Potential energy U = -MB cosθ is minimum at θ = 0°, so equilibrium is stable.
Common trap: Students often choose formula without checking whether the point is axial, equatorial, or a general point.
NEET Question 45Torque on a magnetic dipole in uniform magnetic field is maximum when θ is
A) 0°
B) 45°
C) 90°
D) 180°
Correct Answer: C
Difficulty: Medium-Difficult
Concept Tested: Torque on dipole
Detailed Explanation: τ = MB sinθ is maximum when sinθ = 1, i.e. θ = 90°.
Common trap: Students often choose formula without checking whether the point is axial, equatorial, or a general point.
Difficulty: Medium-Difficult
Concept Tested: Torque on dipole
Detailed Explanation: τ = MB sinθ is maximum when sinθ = 1, i.e. θ = 90°.
Common trap: Students often choose formula without checking whether the point is axial, equatorial, or a general point.
NEET Question 46Direction of magnetic moment of a bar magnet is
A) N to S outside the magnet
B) S to N inside the magnet
C) Always downward
D) Opposite to magnetic field lines everywhere
Correct Answer: B
Difficulty: Medium-Difficult
Concept Tested: Magnetic moment direction
Detailed Explanation: Magnetic moment vector is directed from south pole to north pole inside the magnet.
Common trap: Students often choose formula without checking whether the point is axial, equatorial, or a general point.
Difficulty: Medium-Difficult
Concept Tested: Magnetic moment direction
Detailed Explanation: Magnetic moment vector is directed from south pole to north pole inside the magnet.
Common trap: Students often choose formula without checking whether the point is axial, equatorial, or a general point.
NEET Question 47If distance from a short magnet is doubled, axial magnetic field becomes
A) 1/2
B) 1/4
C) 1/8
D) 1/16
Correct Answer: C
Difficulty: Medium-Difficult
Concept Tested: Short magnet inverse-cube law
Detailed Explanation: For a short magnet, B_axial ∝ 1/r³. Doubling r makes field 1/8.
Common trap: Students often choose formula without checking whether the point is axial, equatorial, or a general point.
Difficulty: Medium-Difficult
Concept Tested: Short magnet inverse-cube law
Detailed Explanation: For a short magnet, B_axial ∝ 1/r³. Doubling r makes field 1/8.
Common trap: Students often choose formula without checking whether the point is axial, equatorial, or a general point.
NEET Question 48Magnetic field lines never intersect because
A) they are imaginary
B) magnetic field has unique direction at a point
C) monopoles exist
D) field is scalar
Correct Answer: B
Difficulty: Medium-Difficult
Concept Tested: Properties of magnetic field lines
Detailed Explanation: If two field lines intersect, there would be two directions of magnetic field at the same point, which is impossible.
Common trap: Students often choose formula without checking whether the point is axial, equatorial, or a general point.
Difficulty: Medium-Difficult
Concept Tested: Properties of magnetic field lines
Detailed Explanation: If two field lines intersect, there would be two directions of magnetic field at the same point, which is impossible.
Common trap: Students often choose formula without checking whether the point is axial, equatorial, or a general point.
NEET Question 49For a short bar magnet, the magnetic field at an axial point and equatorial point at the same distance are in the ratio
A) 1 : 1
B) 2 : 1
C) 1 : 2
D) 4 : 1
Correct Answer: B
Difficulty: Medium-Difficult
Concept Tested: Axial and equatorial field comparison
Detailed Explanation: For a short magnet, B_axial = (μ₀/4π)(2M/r³) and B_equatorial = (μ₀/4π)(M/r³). Hence ratio is 2:1.
Common trap: Students often choose formula without checking whether the point is axial, equatorial, or a general point.
Difficulty: Medium-Difficult
Concept Tested: Axial and equatorial field comparison
Detailed Explanation: For a short magnet, B_axial = (μ₀/4π)(2M/r³) and B_equatorial = (μ₀/4π)(M/r³). Hence ratio is 2:1.
Common trap: Students often choose formula without checking whether the point is axial, equatorial, or a general point.
NEET Question 50A bar magnet is broken into two equal pieces perpendicular to its length. Which statement is correct?
A) Each piece has only one pole
B) Magnetic monopoles are formed
C) Each piece is a complete magnet
D) Magnetic moment becomes zero
Correct Answer: C
Difficulty: Medium-Difficult
Concept Tested: Broken magnet
Detailed Explanation: Every broken piece again has north and south poles. Magnetic monopoles are not produced by breaking a magnet.
Common trap: Students often choose formula without checking whether the point is axial, equatorial, or a general point.
Difficulty: Medium-Difficult
Concept Tested: Broken magnet
Detailed Explanation: Every broken piece again has north and south poles. Magnetic monopoles are not produced by breaking a magnet.
Common trap: Students often choose formula without checking whether the point is axial, equatorial, or a general point.
NEET Question 51Net magnetic flux through any closed surface is
A) μ₀ times magnetic pole inside
B) zero
C) BA always
D) infinite for a bar magnet
Correct Answer: B
Difficulty: Medium-Difficult
Concept Tested: Gauss law of magnetism
Detailed Explanation: Gauss law of magnetism gives ∮B·dA = 0 because magnetic monopoles do not exist.
Common trap: Students often choose formula without checking whether the point is axial, equatorial, or a general point.
Difficulty: Medium-Difficult
Concept Tested: Gauss law of magnetism
Detailed Explanation: Gauss law of magnetism gives ∮B·dA = 0 because magnetic monopoles do not exist.
Common trap: Students often choose formula without checking whether the point is axial, equatorial, or a general point.
NEET Question 52A magnetic dipole is in stable equilibrium when angle between M and B is
A) 0°
B) 90°
C) 180°
D) 270°
Correct Answer: A
Difficulty: Medium-Difficult
Concept Tested: Magnetic potential energy
Detailed Explanation: Potential energy U = -MB cosθ is minimum at θ = 0°, so equilibrium is stable.
Common trap: Students often choose formula without checking whether the point is axial, equatorial, or a general point.
Difficulty: Medium-Difficult
Concept Tested: Magnetic potential energy
Detailed Explanation: Potential energy U = -MB cosθ is minimum at θ = 0°, so equilibrium is stable.
Common trap: Students often choose formula without checking whether the point is axial, equatorial, or a general point.
NEET Question 53Torque on a magnetic dipole in uniform magnetic field is maximum when θ is
A) 0°
B) 45°
C) 90°
D) 180°
Correct Answer: C
Difficulty: Medium-Difficult
Concept Tested: Torque on dipole
Detailed Explanation: τ = MB sinθ is maximum when sinθ = 1, i.e. θ = 90°.
Common trap: Students often choose formula without checking whether the point is axial, equatorial, or a general point.
Difficulty: Medium-Difficult
Concept Tested: Torque on dipole
Detailed Explanation: τ = MB sinθ is maximum when sinθ = 1, i.e. θ = 90°.
Common trap: Students often choose formula without checking whether the point is axial, equatorial, or a general point.
NEET Question 54Direction of magnetic moment of a bar magnet is
A) N to S outside the magnet
B) S to N inside the magnet
C) Always downward
D) Opposite to magnetic field lines everywhere
Correct Answer: B
Difficulty: Medium-Difficult
Concept Tested: Magnetic moment direction
Detailed Explanation: Magnetic moment vector is directed from south pole to north pole inside the magnet.
Common trap: Students often choose formula without checking whether the point is axial, equatorial, or a general point.
Difficulty: Medium-Difficult
Concept Tested: Magnetic moment direction
Detailed Explanation: Magnetic moment vector is directed from south pole to north pole inside the magnet.
Common trap: Students often choose formula without checking whether the point is axial, equatorial, or a general point.
NEET Question 55If distance from a short magnet is doubled, axial magnetic field becomes
A) 1/2
B) 1/4
C) 1/8
D) 1/16
Correct Answer: C
Difficulty: Medium-Difficult
Concept Tested: Short magnet inverse-cube law
Detailed Explanation: For a short magnet, B_axial ∝ 1/r³. Doubling r makes field 1/8.
Common trap: Students often choose formula without checking whether the point is axial, equatorial, or a general point.
Difficulty: Medium-Difficult
Concept Tested: Short magnet inverse-cube law
Detailed Explanation: For a short magnet, B_axial ∝ 1/r³. Doubling r makes field 1/8.
Common trap: Students often choose formula without checking whether the point is axial, equatorial, or a general point.
NEET Question 56Magnetic field lines never intersect because
A) they are imaginary
B) magnetic field has unique direction at a point
C) monopoles exist
D) field is scalar
Correct Answer: B
Difficulty: Medium-Difficult
Concept Tested: Properties of magnetic field lines
Detailed Explanation: If two field lines intersect, there would be two directions of magnetic field at the same point, which is impossible.
Common trap: Students often choose formula without checking whether the point is axial, equatorial, or a general point.
Difficulty: Medium-Difficult
Concept Tested: Properties of magnetic field lines
Detailed Explanation: If two field lines intersect, there would be two directions of magnetic field at the same point, which is impossible.
Common trap: Students often choose formula without checking whether the point is axial, equatorial, or a general point.
NEET Question 57For a short bar magnet, the magnetic field at an axial point and equatorial point at the same distance are in the ratio
A) 1 : 1
B) 2 : 1
C) 1 : 2
D) 4 : 1
Correct Answer: B
Difficulty: Medium-Difficult
Concept Tested: Axial and equatorial field comparison
Detailed Explanation: For a short magnet, B_axial = (μ₀/4π)(2M/r³) and B_equatorial = (μ₀/4π)(M/r³). Hence ratio is 2:1.
Common trap: Students often choose formula without checking whether the point is axial, equatorial, or a general point.
Difficulty: Medium-Difficult
Concept Tested: Axial and equatorial field comparison
Detailed Explanation: For a short magnet, B_axial = (μ₀/4π)(2M/r³) and B_equatorial = (μ₀/4π)(M/r³). Hence ratio is 2:1.
Common trap: Students often choose formula without checking whether the point is axial, equatorial, or a general point.
NEET Question 58A bar magnet is broken into two equal pieces perpendicular to its length. Which statement is correct?
A) Each piece has only one pole
B) Magnetic monopoles are formed
C) Each piece is a complete magnet
D) Magnetic moment becomes zero
Correct Answer: C
Difficulty: Medium-Difficult
Concept Tested: Broken magnet
Detailed Explanation: Every broken piece again has north and south poles. Magnetic monopoles are not produced by breaking a magnet.
Common trap: Students often choose formula without checking whether the point is axial, equatorial, or a general point.
Difficulty: Medium-Difficult
Concept Tested: Broken magnet
Detailed Explanation: Every broken piece again has north and south poles. Magnetic monopoles are not produced by breaking a magnet.
Common trap: Students often choose formula without checking whether the point is axial, equatorial, or a general point.
NEET Question 59Net magnetic flux through any closed surface is
A) μ₀ times magnetic pole inside
B) zero
C) BA always
D) infinite for a bar magnet
Correct Answer: B
Difficulty: Medium-Difficult
Concept Tested: Gauss law of magnetism
Detailed Explanation: Gauss law of magnetism gives ∮B·dA = 0 because magnetic monopoles do not exist.
Common trap: Students often choose formula without checking whether the point is axial, equatorial, or a general point.
Difficulty: Medium-Difficult
Concept Tested: Gauss law of magnetism
Detailed Explanation: Gauss law of magnetism gives ∮B·dA = 0 because magnetic monopoles do not exist.
Common trap: Students often choose formula without checking whether the point is axial, equatorial, or a general point.
NEET Question 60A magnetic dipole is in stable equilibrium when angle between M and B is
A) 0°
B) 90°
C) 180°
D) 270°
Correct Answer: A
Difficulty: Medium-Difficult
Concept Tested: Magnetic potential energy
Detailed Explanation: Potential energy U = -MB cosθ is minimum at θ = 0°, so equilibrium is stable.
Common trap: Students often choose formula without checking whether the point is axial, equatorial, or a general point.
Difficulty: Medium-Difficult
Concept Tested: Magnetic potential energy
Detailed Explanation: Potential energy U = -MB cosθ is minimum at θ = 0°, so equilibrium is stable.
Common trap: Students often choose formula without checking whether the point is axial, equatorial, or a general point.
NEET Question 61Torque on a magnetic dipole in uniform magnetic field is maximum when θ is
A) 0°
B) 45°
C) 90°
D) 180°
Correct Answer: C
Difficulty: Medium-Difficult
Concept Tested: Torque on dipole
Detailed Explanation: τ = MB sinθ is maximum when sinθ = 1, i.e. θ = 90°.
Common trap: Students often choose formula without checking whether the point is axial, equatorial, or a general point.
Difficulty: Medium-Difficult
Concept Tested: Torque on dipole
Detailed Explanation: τ = MB sinθ is maximum when sinθ = 1, i.e. θ = 90°.
Common trap: Students often choose formula without checking whether the point is axial, equatorial, or a general point.
NEET Question 62Direction of magnetic moment of a bar magnet is
A) N to S outside the magnet
B) S to N inside the magnet
C) Always downward
D) Opposite to magnetic field lines everywhere
Correct Answer: B
Difficulty: Medium-Difficult
Concept Tested: Magnetic moment direction
Detailed Explanation: Magnetic moment vector is directed from south pole to north pole inside the magnet.
Common trap: Students often choose formula without checking whether the point is axial, equatorial, or a general point.
Difficulty: Medium-Difficult
Concept Tested: Magnetic moment direction
Detailed Explanation: Magnetic moment vector is directed from south pole to north pole inside the magnet.
Common trap: Students often choose formula without checking whether the point is axial, equatorial, or a general point.
NEET Question 63If distance from a short magnet is doubled, axial magnetic field becomes
A) 1/2
B) 1/4
C) 1/8
D) 1/16
Correct Answer: C
Difficulty: Medium-Difficult
Concept Tested: Short magnet inverse-cube law
Detailed Explanation: For a short magnet, B_axial ∝ 1/r³. Doubling r makes field 1/8.
Common trap: Students often choose formula without checking whether the point is axial, equatorial, or a general point.
Difficulty: Medium-Difficult
Concept Tested: Short magnet inverse-cube law
Detailed Explanation: For a short magnet, B_axial ∝ 1/r³. Doubling r makes field 1/8.
Common trap: Students often choose formula without checking whether the point is axial, equatorial, or a general point.
NEET Question 64Magnetic field lines never intersect because
A) they are imaginary
B) magnetic field has unique direction at a point
C) monopoles exist
D) field is scalar
Correct Answer: B
Difficulty: Medium-Difficult
Concept Tested: Properties of magnetic field lines
Detailed Explanation: If two field lines intersect, there would be two directions of magnetic field at the same point, which is impossible.
Common trap: Students often choose formula without checking whether the point is axial, equatorial, or a general point.
Difficulty: Medium-Difficult
Concept Tested: Properties of magnetic field lines
Detailed Explanation: If two field lines intersect, there would be two directions of magnetic field at the same point, which is impossible.
Common trap: Students often choose formula without checking whether the point is axial, equatorial, or a general point.
NEET Question 65For a short bar magnet, the magnetic field at an axial point and equatorial point at the same distance are in the ratio
A) 1 : 1
B) 2 : 1
C) 1 : 2
D) 4 : 1
Correct Answer: B
Difficulty: Medium-Difficult
Concept Tested: Axial and equatorial field comparison
Detailed Explanation: For a short magnet, B_axial = (μ₀/4π)(2M/r³) and B_equatorial = (μ₀/4π)(M/r³). Hence ratio is 2:1.
Common trap: Students often choose formula without checking whether the point is axial, equatorial, or a general point.
Difficulty: Medium-Difficult
Concept Tested: Axial and equatorial field comparison
Detailed Explanation: For a short magnet, B_axial = (μ₀/4π)(2M/r³) and B_equatorial = (μ₀/4π)(M/r³). Hence ratio is 2:1.
Common trap: Students often choose formula without checking whether the point is axial, equatorial, or a general point.
NEET Question 66A bar magnet is broken into two equal pieces perpendicular to its length. Which statement is correct?
A) Each piece has only one pole
B) Magnetic monopoles are formed
C) Each piece is a complete magnet
D) Magnetic moment becomes zero
Correct Answer: C
Difficulty: Medium-Difficult
Concept Tested: Broken magnet
Detailed Explanation: Every broken piece again has north and south poles. Magnetic monopoles are not produced by breaking a magnet.
Common trap: Students often choose formula without checking whether the point is axial, equatorial, or a general point.
Difficulty: Medium-Difficult
Concept Tested: Broken magnet
Detailed Explanation: Every broken piece again has north and south poles. Magnetic monopoles are not produced by breaking a magnet.
Common trap: Students often choose formula without checking whether the point is axial, equatorial, or a general point.
NEET Question 67Net magnetic flux through any closed surface is
A) μ₀ times magnetic pole inside
B) zero
C) BA always
D) infinite for a bar magnet
Correct Answer: B
Difficulty: Medium-Difficult
Concept Tested: Gauss law of magnetism
Detailed Explanation: Gauss law of magnetism gives ∮B·dA = 0 because magnetic monopoles do not exist.
Common trap: Students often choose formula without checking whether the point is axial, equatorial, or a general point.
Difficulty: Medium-Difficult
Concept Tested: Gauss law of magnetism
Detailed Explanation: Gauss law of magnetism gives ∮B·dA = 0 because magnetic monopoles do not exist.
Common trap: Students often choose formula without checking whether the point is axial, equatorial, or a general point.
NEET Question 68A magnetic dipole is in stable equilibrium when angle between M and B is
A) 0°
B) 90°
C) 180°
D) 270°
Correct Answer: A
Difficulty: Medium-Difficult
Concept Tested: Magnetic potential energy
Detailed Explanation: Potential energy U = -MB cosθ is minimum at θ = 0°, so equilibrium is stable.
Common trap: Students often choose formula without checking whether the point is axial, equatorial, or a general point.
Difficulty: Medium-Difficult
Concept Tested: Magnetic potential energy
Detailed Explanation: Potential energy U = -MB cosθ is minimum at θ = 0°, so equilibrium is stable.
Common trap: Students often choose formula without checking whether the point is axial, equatorial, or a general point.
NEET Question 69Torque on a magnetic dipole in uniform magnetic field is maximum when θ is
A) 0°
B) 45°
C) 90°
D) 180°
Correct Answer: C
Difficulty: Medium-Difficult
Concept Tested: Torque on dipole
Detailed Explanation: τ = MB sinθ is maximum when sinθ = 1, i.e. θ = 90°.
Common trap: Students often choose formula without checking whether the point is axial, equatorial, or a general point.
Difficulty: Medium-Difficult
Concept Tested: Torque on dipole
Detailed Explanation: τ = MB sinθ is maximum when sinθ = 1, i.e. θ = 90°.
Common trap: Students often choose formula without checking whether the point is axial, equatorial, or a general point.
NEET Question 70Direction of magnetic moment of a bar magnet is
A) N to S outside the magnet
B) S to N inside the magnet
C) Always downward
D) Opposite to magnetic field lines everywhere
Correct Answer: B
Difficulty: Medium-Difficult
Concept Tested: Magnetic moment direction
Detailed Explanation: Magnetic moment vector is directed from south pole to north pole inside the magnet.
Common trap: Students often choose formula without checking whether the point is axial, equatorial, or a general point.
Difficulty: Medium-Difficult
Concept Tested: Magnetic moment direction
Detailed Explanation: Magnetic moment vector is directed from south pole to north pole inside the magnet.
Common trap: Students often choose formula without checking whether the point is axial, equatorial, or a general point.
NEET Question 71If distance from a short magnet is doubled, axial magnetic field becomes
A) 1/2
B) 1/4
C) 1/8
D) 1/16
Correct Answer: C
Difficulty: Medium-Difficult
Concept Tested: Short magnet inverse-cube law
Detailed Explanation: For a short magnet, B_axial ∝ 1/r³. Doubling r makes field 1/8.
Common trap: Students often choose formula without checking whether the point is axial, equatorial, or a general point.
Difficulty: Medium-Difficult
Concept Tested: Short magnet inverse-cube law
Detailed Explanation: For a short magnet, B_axial ∝ 1/r³. Doubling r makes field 1/8.
Common trap: Students often choose formula without checking whether the point is axial, equatorial, or a general point.
NEET Question 72Magnetic field lines never intersect because
A) they are imaginary
B) magnetic field has unique direction at a point
C) monopoles exist
D) field is scalar
Correct Answer: B
Difficulty: Medium-Difficult
Concept Tested: Properties of magnetic field lines
Detailed Explanation: If two field lines intersect, there would be two directions of magnetic field at the same point, which is impossible.
Common trap: Students often choose formula without checking whether the point is axial, equatorial, or a general point.
Difficulty: Medium-Difficult
Concept Tested: Properties of magnetic field lines
Detailed Explanation: If two field lines intersect, there would be two directions of magnetic field at the same point, which is impossible.
Common trap: Students often choose formula without checking whether the point is axial, equatorial, or a general point.
NEET Question 73For a short bar magnet, the magnetic field at an axial point and equatorial point at the same distance are in the ratio
A) 1 : 1
B) 2 : 1
C) 1 : 2
D) 4 : 1
Correct Answer: B
Difficulty: Medium-Difficult
Concept Tested: Axial and equatorial field comparison
Detailed Explanation: For a short magnet, B_axial = (μ₀/4π)(2M/r³) and B_equatorial = (μ₀/4π)(M/r³). Hence ratio is 2:1.
Common trap: Students often choose formula without checking whether the point is axial, equatorial, or a general point.
Difficulty: Medium-Difficult
Concept Tested: Axial and equatorial field comparison
Detailed Explanation: For a short magnet, B_axial = (μ₀/4π)(2M/r³) and B_equatorial = (μ₀/4π)(M/r³). Hence ratio is 2:1.
Common trap: Students often choose formula without checking whether the point is axial, equatorial, or a general point.
NEET Question 74A bar magnet is broken into two equal pieces perpendicular to its length. Which statement is correct?
A) Each piece has only one pole
B) Magnetic monopoles are formed
C) Each piece is a complete magnet
D) Magnetic moment becomes zero
Correct Answer: C
Difficulty: Medium-Difficult
Concept Tested: Broken magnet
Detailed Explanation: Every broken piece again has north and south poles. Magnetic monopoles are not produced by breaking a magnet.
Common trap: Students often choose formula without checking whether the point is axial, equatorial, or a general point.
Difficulty: Medium-Difficult
Concept Tested: Broken magnet
Detailed Explanation: Every broken piece again has north and south poles. Magnetic monopoles are not produced by breaking a magnet.
Common trap: Students often choose formula without checking whether the point is axial, equatorial, or a general point.
NEET Question 75Net magnetic flux through any closed surface is
A) μ₀ times magnetic pole inside
B) zero
C) BA always
D) infinite for a bar magnet
Correct Answer: B
Difficulty: Medium-Difficult
Concept Tested: Gauss law of magnetism
Detailed Explanation: Gauss law of magnetism gives ∮B·dA = 0 because magnetic monopoles do not exist.
Common trap: Students often choose formula without checking whether the point is axial, equatorial, or a general point.
Difficulty: Medium-Difficult
Concept Tested: Gauss law of magnetism
Detailed Explanation: Gauss law of magnetism gives ∮B·dA = 0 because magnetic monopoles do not exist.
Common trap: Students often choose formula without checking whether the point is axial, equatorial, or a general point.
NEET Question 76A magnetic dipole is in stable equilibrium when angle between M and B is
A) 0°
B) 90°
C) 180°
D) 270°
Correct Answer: A
Difficulty: Medium-Difficult
Concept Tested: Magnetic potential energy
Detailed Explanation: Potential energy U = -MB cosθ is minimum at θ = 0°, so equilibrium is stable.
Common trap: Students often choose formula without checking whether the point is axial, equatorial, or a general point.
Difficulty: Medium-Difficult
Concept Tested: Magnetic potential energy
Detailed Explanation: Potential energy U = -MB cosθ is minimum at θ = 0°, so equilibrium is stable.
Common trap: Students often choose formula without checking whether the point is axial, equatorial, or a general point.
NEET Question 77Torque on a magnetic dipole in uniform magnetic field is maximum when θ is
A) 0°
B) 45°
C) 90°
D) 180°
Correct Answer: C
Difficulty: Medium-Difficult
Concept Tested: Torque on dipole
Detailed Explanation: τ = MB sinθ is maximum when sinθ = 1, i.e. θ = 90°.
Common trap: Students often choose formula without checking whether the point is axial, equatorial, or a general point.
Difficulty: Medium-Difficult
Concept Tested: Torque on dipole
Detailed Explanation: τ = MB sinθ is maximum when sinθ = 1, i.e. θ = 90°.
Common trap: Students often choose formula without checking whether the point is axial, equatorial, or a general point.
NEET Question 78Direction of magnetic moment of a bar magnet is
A) N to S outside the magnet
B) S to N inside the magnet
C) Always downward
D) Opposite to magnetic field lines everywhere
Correct Answer: B
Difficulty: Medium-Difficult
Concept Tested: Magnetic moment direction
Detailed Explanation: Magnetic moment vector is directed from south pole to north pole inside the magnet.
Common trap: Students often choose formula without checking whether the point is axial, equatorial, or a general point.
Difficulty: Medium-Difficult
Concept Tested: Magnetic moment direction
Detailed Explanation: Magnetic moment vector is directed from south pole to north pole inside the magnet.
Common trap: Students often choose formula without checking whether the point is axial, equatorial, or a general point.
NEET Question 79If distance from a short magnet is doubled, axial magnetic field becomes
A) 1/2
B) 1/4
C) 1/8
D) 1/16
Correct Answer: C
Difficulty: Medium-Difficult
Concept Tested: Short magnet inverse-cube law
Detailed Explanation: For a short magnet, B_axial ∝ 1/r³. Doubling r makes field 1/8.
Common trap: Students often choose formula without checking whether the point is axial, equatorial, or a general point.
Difficulty: Medium-Difficult
Concept Tested: Short magnet inverse-cube law
Detailed Explanation: For a short magnet, B_axial ∝ 1/r³. Doubling r makes field 1/8.
Common trap: Students often choose formula without checking whether the point is axial, equatorial, or a general point.
NEET Question 80Magnetic field lines never intersect because
A) they are imaginary
B) magnetic field has unique direction at a point
C) monopoles exist
D) field is scalar
Correct Answer: B
Difficulty: Medium-Difficult
Concept Tested: Properties of magnetic field lines
Detailed Explanation: If two field lines intersect, there would be two directions of magnetic field at the same point, which is impossible.
Common trap: Students often choose formula without checking whether the point is axial, equatorial, or a general point.
Difficulty: Medium-Difficult
Concept Tested: Properties of magnetic field lines
Detailed Explanation: If two field lines intersect, there would be two directions of magnetic field at the same point, which is impossible.
Common trap: Students often choose formula without checking whether the point is axial, equatorial, or a general point.
NEET Question 81For a short bar magnet, the magnetic field at an axial point and equatorial point at the same distance are in the ratio
A) 1 : 1
B) 2 : 1
C) 1 : 2
D) 4 : 1
Correct Answer: B
Difficulty: Medium-Difficult
Concept Tested: Axial and equatorial field comparison
Detailed Explanation: For a short magnet, B_axial = (μ₀/4π)(2M/r³) and B_equatorial = (μ₀/4π)(M/r³). Hence ratio is 2:1.
Common trap: Students often choose formula without checking whether the point is axial, equatorial, or a general point.
Difficulty: Medium-Difficult
Concept Tested: Axial and equatorial field comparison
Detailed Explanation: For a short magnet, B_axial = (μ₀/4π)(2M/r³) and B_equatorial = (μ₀/4π)(M/r³). Hence ratio is 2:1.
Common trap: Students often choose formula without checking whether the point is axial, equatorial, or a general point.
NEET Question 82A bar magnet is broken into two equal pieces perpendicular to its length. Which statement is correct?
A) Each piece has only one pole
B) Magnetic monopoles are formed
C) Each piece is a complete magnet
D) Magnetic moment becomes zero
Correct Answer: C
Difficulty: Medium-Difficult
Concept Tested: Broken magnet
Detailed Explanation: Every broken piece again has north and south poles. Magnetic monopoles are not produced by breaking a magnet.
Common trap: Students often choose formula without checking whether the point is axial, equatorial, or a general point.
Difficulty: Medium-Difficult
Concept Tested: Broken magnet
Detailed Explanation: Every broken piece again has north and south poles. Magnetic monopoles are not produced by breaking a magnet.
Common trap: Students often choose formula without checking whether the point is axial, equatorial, or a general point.
NEET Question 83Net magnetic flux through any closed surface is
A) μ₀ times magnetic pole inside
B) zero
C) BA always
D) infinite for a bar magnet
Correct Answer: B
Difficulty: Medium-Difficult
Concept Tested: Gauss law of magnetism
Detailed Explanation: Gauss law of magnetism gives ∮B·dA = 0 because magnetic monopoles do not exist.
Common trap: Students often choose formula without checking whether the point is axial, equatorial, or a general point.
Difficulty: Medium-Difficult
Concept Tested: Gauss law of magnetism
Detailed Explanation: Gauss law of magnetism gives ∮B·dA = 0 because magnetic monopoles do not exist.
Common trap: Students often choose formula without checking whether the point is axial, equatorial, or a general point.
NEET Question 84A magnetic dipole is in stable equilibrium when angle between M and B is
A) 0°
B) 90°
C) 180°
D) 270°
Correct Answer: A
Difficulty: Medium-Difficult
Concept Tested: Magnetic potential energy
Detailed Explanation: Potential energy U = -MB cosθ is minimum at θ = 0°, so equilibrium is stable.
Common trap: Students often choose formula without checking whether the point is axial, equatorial, or a general point.
Difficulty: Medium-Difficult
Concept Tested: Magnetic potential energy
Detailed Explanation: Potential energy U = -MB cosθ is minimum at θ = 0°, so equilibrium is stable.
Common trap: Students often choose formula without checking whether the point is axial, equatorial, or a general point.
NEET Question 85Torque on a magnetic dipole in uniform magnetic field is maximum when θ is
A) 0°
B) 45°
C) 90°
D) 180°
Correct Answer: C
Difficulty: Medium-Difficult
Concept Tested: Torque on dipole
Detailed Explanation: τ = MB sinθ is maximum when sinθ = 1, i.e. θ = 90°.
Common trap: Students often choose formula without checking whether the point is axial, equatorial, or a general point.
Difficulty: Medium-Difficult
Concept Tested: Torque on dipole
Detailed Explanation: τ = MB sinθ is maximum when sinθ = 1, i.e. θ = 90°.
Common trap: Students often choose formula without checking whether the point is axial, equatorial, or a general point.
NEET Question 86Direction of magnetic moment of a bar magnet is
A) N to S outside the magnet
B) S to N inside the magnet
C) Always downward
D) Opposite to magnetic field lines everywhere
Correct Answer: B
Difficulty: Medium-Difficult
Concept Tested: Magnetic moment direction
Detailed Explanation: Magnetic moment vector is directed from south pole to north pole inside the magnet.
Common trap: Students often choose formula without checking whether the point is axial, equatorial, or a general point.
Difficulty: Medium-Difficult
Concept Tested: Magnetic moment direction
Detailed Explanation: Magnetic moment vector is directed from south pole to north pole inside the magnet.
Common trap: Students often choose formula without checking whether the point is axial, equatorial, or a general point.
NEET Question 87If distance from a short magnet is doubled, axial magnetic field becomes
A) 1/2
B) 1/4
C) 1/8
D) 1/16
Correct Answer: C
Difficulty: Medium-Difficult
Concept Tested: Short magnet inverse-cube law
Detailed Explanation: For a short magnet, B_axial ∝ 1/r³. Doubling r makes field 1/8.
Common trap: Students often choose formula without checking whether the point is axial, equatorial, or a general point.
Difficulty: Medium-Difficult
Concept Tested: Short magnet inverse-cube law
Detailed Explanation: For a short magnet, B_axial ∝ 1/r³. Doubling r makes field 1/8.
Common trap: Students often choose formula without checking whether the point is axial, equatorial, or a general point.
NEET Question 88Magnetic field lines never intersect because
A) they are imaginary
B) magnetic field has unique direction at a point
C) monopoles exist
D) field is scalar
Correct Answer: B
Difficulty: Medium-Difficult
Concept Tested: Properties of magnetic field lines
Detailed Explanation: If two field lines intersect, there would be two directions of magnetic field at the same point, which is impossible.
Common trap: Students often choose formula without checking whether the point is axial, equatorial, or a general point.
Difficulty: Medium-Difficult
Concept Tested: Properties of magnetic field lines
Detailed Explanation: If two field lines intersect, there would be two directions of magnetic field at the same point, which is impossible.
Common trap: Students often choose formula without checking whether the point is axial, equatorial, or a general point.
NEET Question 89For a short bar magnet, the magnetic field at an axial point and equatorial point at the same distance are in the ratio
A) 1 : 1
B) 2 : 1
C) 1 : 2
D) 4 : 1
Correct Answer: B
Difficulty: Medium-Difficult
Concept Tested: Axial and equatorial field comparison
Detailed Explanation: For a short magnet, B_axial = (μ₀/4π)(2M/r³) and B_equatorial = (μ₀/4π)(M/r³). Hence ratio is 2:1.
Common trap: Students often choose formula without checking whether the point is axial, equatorial, or a general point.
Difficulty: Medium-Difficult
Concept Tested: Axial and equatorial field comparison
Detailed Explanation: For a short magnet, B_axial = (μ₀/4π)(2M/r³) and B_equatorial = (μ₀/4π)(M/r³). Hence ratio is 2:1.
Common trap: Students often choose formula without checking whether the point is axial, equatorial, or a general point.
NEET Question 90A bar magnet is broken into two equal pieces perpendicular to its length. Which statement is correct?
A) Each piece has only one pole
B) Magnetic monopoles are formed
C) Each piece is a complete magnet
D) Magnetic moment becomes zero
Correct Answer: C
Difficulty: Medium-Difficult
Concept Tested: Broken magnet
Detailed Explanation: Every broken piece again has north and south poles. Magnetic monopoles are not produced by breaking a magnet.
Common trap: Students often choose formula without checking whether the point is axial, equatorial, or a general point.
Difficulty: Medium-Difficult
Concept Tested: Broken magnet
Detailed Explanation: Every broken piece again has north and south poles. Magnetic monopoles are not produced by breaking a magnet.
Common trap: Students often choose formula without checking whether the point is axial, equatorial, or a general point.
NEET Question 91Net magnetic flux through any closed surface is
A) μ₀ times magnetic pole inside
B) zero
C) BA always
D) infinite for a bar magnet
Correct Answer: B
Difficulty: Medium-Difficult
Concept Tested: Gauss law of magnetism
Detailed Explanation: Gauss law of magnetism gives ∮B·dA = 0 because magnetic monopoles do not exist.
Common trap: Students often choose formula without checking whether the point is axial, equatorial, or a general point.
Difficulty: Medium-Difficult
Concept Tested: Gauss law of magnetism
Detailed Explanation: Gauss law of magnetism gives ∮B·dA = 0 because magnetic monopoles do not exist.
Common trap: Students often choose formula without checking whether the point is axial, equatorial, or a general point.
NEET Question 92A magnetic dipole is in stable equilibrium when angle between M and B is
A) 0°
B) 90°
C) 180°
D) 270°
Correct Answer: A
Difficulty: Medium-Difficult
Concept Tested: Magnetic potential energy
Detailed Explanation: Potential energy U = -MB cosθ is minimum at θ = 0°, so equilibrium is stable.
Common trap: Students often choose formula without checking whether the point is axial, equatorial, or a general point.
Difficulty: Medium-Difficult
Concept Tested: Magnetic potential energy
Detailed Explanation: Potential energy U = -MB cosθ is minimum at θ = 0°, so equilibrium is stable.
Common trap: Students often choose formula without checking whether the point is axial, equatorial, or a general point.
NEET Question 93Torque on a magnetic dipole in uniform magnetic field is maximum when θ is
A) 0°
B) 45°
C) 90°
D) 180°
Correct Answer: C
Difficulty: Medium-Difficult
Concept Tested: Torque on dipole
Detailed Explanation: τ = MB sinθ is maximum when sinθ = 1, i.e. θ = 90°.
Common trap: Students often choose formula without checking whether the point is axial, equatorial, or a general point.
Difficulty: Medium-Difficult
Concept Tested: Torque on dipole
Detailed Explanation: τ = MB sinθ is maximum when sinθ = 1, i.e. θ = 90°.
Common trap: Students often choose formula without checking whether the point is axial, equatorial, or a general point.
NEET Question 94Direction of magnetic moment of a bar magnet is
A) N to S outside the magnet
B) S to N inside the magnet
C) Always downward
D) Opposite to magnetic field lines everywhere
Correct Answer: B
Difficulty: Medium-Difficult
Concept Tested: Magnetic moment direction
Detailed Explanation: Magnetic moment vector is directed from south pole to north pole inside the magnet.
Common trap: Students often choose formula without checking whether the point is axial, equatorial, or a general point.
Difficulty: Medium-Difficult
Concept Tested: Magnetic moment direction
Detailed Explanation: Magnetic moment vector is directed from south pole to north pole inside the magnet.
Common trap: Students often choose formula without checking whether the point is axial, equatorial, or a general point.
NEET Question 95If distance from a short magnet is doubled, axial magnetic field becomes
A) 1/2
B) 1/4
C) 1/8
D) 1/16
Correct Answer: C
Difficulty: Medium-Difficult
Concept Tested: Short magnet inverse-cube law
Detailed Explanation: For a short magnet, B_axial ∝ 1/r³. Doubling r makes field 1/8.
Common trap: Students often choose formula without checking whether the point is axial, equatorial, or a general point.
Difficulty: Medium-Difficult
Concept Tested: Short magnet inverse-cube law
Detailed Explanation: For a short magnet, B_axial ∝ 1/r³. Doubling r makes field 1/8.
Common trap: Students often choose formula without checking whether the point is axial, equatorial, or a general point.
NEET Question 96Magnetic field lines never intersect because
A) they are imaginary
B) magnetic field has unique direction at a point
C) monopoles exist
D) field is scalar
Correct Answer: B
Difficulty: Medium-Difficult
Concept Tested: Properties of magnetic field lines
Detailed Explanation: If two field lines intersect, there would be two directions of magnetic field at the same point, which is impossible.
Common trap: Students often choose formula without checking whether the point is axial, equatorial, or a general point.
Difficulty: Medium-Difficult
Concept Tested: Properties of magnetic field lines
Detailed Explanation: If two field lines intersect, there would be two directions of magnetic field at the same point, which is impossible.
Common trap: Students often choose formula without checking whether the point is axial, equatorial, or a general point.
NEET Question 97For a short bar magnet, the magnetic field at an axial point and equatorial point at the same distance are in the ratio
A) 1 : 1
B) 2 : 1
C) 1 : 2
D) 4 : 1
Correct Answer: B
Difficulty: Medium-Difficult
Concept Tested: Axial and equatorial field comparison
Detailed Explanation: For a short magnet, B_axial = (μ₀/4π)(2M/r³) and B_equatorial = (μ₀/4π)(M/r³). Hence ratio is 2:1.
Common trap: Students often choose formula without checking whether the point is axial, equatorial, or a general point.
Difficulty: Medium-Difficult
Concept Tested: Axial and equatorial field comparison
Detailed Explanation: For a short magnet, B_axial = (μ₀/4π)(2M/r³) and B_equatorial = (μ₀/4π)(M/r³). Hence ratio is 2:1.
Common trap: Students often choose formula without checking whether the point is axial, equatorial, or a general point.
NEET Question 98A bar magnet is broken into two equal pieces perpendicular to its length. Which statement is correct?
A) Each piece has only one pole
B) Magnetic monopoles are formed
C) Each piece is a complete magnet
D) Magnetic moment becomes zero
Correct Answer: C
Difficulty: Medium-Difficult
Concept Tested: Broken magnet
Detailed Explanation: Every broken piece again has north and south poles. Magnetic monopoles are not produced by breaking a magnet.
Common trap: Students often choose formula without checking whether the point is axial, equatorial, or a general point.
Difficulty: Medium-Difficult
Concept Tested: Broken magnet
Detailed Explanation: Every broken piece again has north and south poles. Magnetic monopoles are not produced by breaking a magnet.
Common trap: Students often choose formula without checking whether the point is axial, equatorial, or a general point.
NEET Question 99Net magnetic flux through any closed surface is
A) μ₀ times magnetic pole inside
B) zero
C) BA always
D) infinite for a bar magnet
Correct Answer: B
Difficulty: Medium-Difficult
Concept Tested: Gauss law of magnetism
Detailed Explanation: Gauss law of magnetism gives ∮B·dA = 0 because magnetic monopoles do not exist.
Common trap: Students often choose formula without checking whether the point is axial, equatorial, or a general point.
Difficulty: Medium-Difficult
Concept Tested: Gauss law of magnetism
Detailed Explanation: Gauss law of magnetism gives ∮B·dA = 0 because magnetic monopoles do not exist.
Common trap: Students often choose formula without checking whether the point is axial, equatorial, or a general point.
NEET Question 100A magnetic dipole is in stable equilibrium when angle between M and B is
A) 0°
B) 90°
C) 180°
D) 270°
Correct Answer: A
Difficulty: Medium-Difficult
Concept Tested: Magnetic potential energy
Detailed Explanation: Potential energy U = -MB cosθ is minimum at θ = 0°, so equilibrium is stable.
Common trap: Students often choose formula without checking whether the point is axial, equatorial, or a general point.
Difficulty: Medium-Difficult
Concept Tested: Magnetic potential energy
Detailed Explanation: Potential energy U = -MB cosθ is minimum at θ = 0°, so equilibrium is stable.
Common trap: Students often choose formula without checking whether the point is axial, equatorial, or a general point.
C. JEE Main MCQs
JEE Main Question 1For a short bar magnet, the magnetic field at an axial point and equatorial point at the same distance are in the ratio
A) 1 : 1
B) 2 : 1
C) 1 : 2
D) 4 : 1
Correct Answer: B
Difficulty: Medium-Difficult
Concept Tested: Axial and equatorial field comparison
Detailed Explanation: For a short magnet, B_axial = (μ₀/4π)(2M/r³) and B_equatorial = (μ₀/4π)(M/r³). Hence ratio is 2:1.
Common trap: Students often choose formula without checking whether the point is axial, equatorial, or a general point.
Difficulty: Medium-Difficult
Concept Tested: Axial and equatorial field comparison
Detailed Explanation: For a short magnet, B_axial = (μ₀/4π)(2M/r³) and B_equatorial = (μ₀/4π)(M/r³). Hence ratio is 2:1.
Common trap: Students often choose formula without checking whether the point is axial, equatorial, or a general point.
JEE Main Question 2A bar magnet is broken into two equal pieces perpendicular to its length. Which statement is correct?
A) Each piece has only one pole
B) Magnetic monopoles are formed
C) Each piece is a complete magnet
D) Magnetic moment becomes zero
Correct Answer: C
Difficulty: Medium-Difficult
Concept Tested: Broken magnet
Detailed Explanation: Every broken piece again has north and south poles. Magnetic monopoles are not produced by breaking a magnet.
Common trap: Students often choose formula without checking whether the point is axial, equatorial, or a general point.
Difficulty: Medium-Difficult
Concept Tested: Broken magnet
Detailed Explanation: Every broken piece again has north and south poles. Magnetic monopoles are not produced by breaking a magnet.
Common trap: Students often choose formula without checking whether the point is axial, equatorial, or a general point.
JEE Main Question 3Net magnetic flux through any closed surface is
A) μ₀ times magnetic pole inside
B) zero
C) BA always
D) infinite for a bar magnet
Correct Answer: B
Difficulty: Medium-Difficult
Concept Tested: Gauss law of magnetism
Detailed Explanation: Gauss law of magnetism gives ∮B·dA = 0 because magnetic monopoles do not exist.
Common trap: Students often choose formula without checking whether the point is axial, equatorial, or a general point.
Difficulty: Medium-Difficult
Concept Tested: Gauss law of magnetism
Detailed Explanation: Gauss law of magnetism gives ∮B·dA = 0 because magnetic monopoles do not exist.
Common trap: Students often choose formula without checking whether the point is axial, equatorial, or a general point.
JEE Main Question 4A magnetic dipole is in stable equilibrium when angle between M and B is
A) 0°
B) 90°
C) 180°
D) 270°
Correct Answer: A
Difficulty: Medium-Difficult
Concept Tested: Magnetic potential energy
Detailed Explanation: Potential energy U = -MB cosθ is minimum at θ = 0°, so equilibrium is stable.
Common trap: Students often choose formula without checking whether the point is axial, equatorial, or a general point.
Difficulty: Medium-Difficult
Concept Tested: Magnetic potential energy
Detailed Explanation: Potential energy U = -MB cosθ is minimum at θ = 0°, so equilibrium is stable.
Common trap: Students often choose formula without checking whether the point is axial, equatorial, or a general point.
JEE Main Question 5Torque on a magnetic dipole in uniform magnetic field is maximum when θ is
A) 0°
B) 45°
C) 90°
D) 180°
Correct Answer: C
Difficulty: Medium-Difficult
Concept Tested: Torque on dipole
Detailed Explanation: τ = MB sinθ is maximum when sinθ = 1, i.e. θ = 90°.
Common trap: Students often choose formula without checking whether the point is axial, equatorial, or a general point.
Difficulty: Medium-Difficult
Concept Tested: Torque on dipole
Detailed Explanation: τ = MB sinθ is maximum when sinθ = 1, i.e. θ = 90°.
Common trap: Students often choose formula without checking whether the point is axial, equatorial, or a general point.
JEE Main Question 6Direction of magnetic moment of a bar magnet is
A) N to S outside the magnet
B) S to N inside the magnet
C) Always downward
D) Opposite to magnetic field lines everywhere
Correct Answer: B
Difficulty: Medium-Difficult
Concept Tested: Magnetic moment direction
Detailed Explanation: Magnetic moment vector is directed from south pole to north pole inside the magnet.
Common trap: Students often choose formula without checking whether the point is axial, equatorial, or a general point.
Difficulty: Medium-Difficult
Concept Tested: Magnetic moment direction
Detailed Explanation: Magnetic moment vector is directed from south pole to north pole inside the magnet.
Common trap: Students often choose formula without checking whether the point is axial, equatorial, or a general point.
JEE Main Question 7If distance from a short magnet is doubled, axial magnetic field becomes
A) 1/2
B) 1/4
C) 1/8
D) 1/16
Correct Answer: C
Difficulty: Medium-Difficult
Concept Tested: Short magnet inverse-cube law
Detailed Explanation: For a short magnet, B_axial ∝ 1/r³. Doubling r makes field 1/8.
Common trap: Students often choose formula without checking whether the point is axial, equatorial, or a general point.
Difficulty: Medium-Difficult
Concept Tested: Short magnet inverse-cube law
Detailed Explanation: For a short magnet, B_axial ∝ 1/r³. Doubling r makes field 1/8.
Common trap: Students often choose formula without checking whether the point is axial, equatorial, or a general point.
JEE Main Question 8Magnetic field lines never intersect because
A) they are imaginary
B) magnetic field has unique direction at a point
C) monopoles exist
D) field is scalar
Correct Answer: B
Difficulty: Medium-Difficult
Concept Tested: Properties of magnetic field lines
Detailed Explanation: If two field lines intersect, there would be two directions of magnetic field at the same point, which is impossible.
Common trap: Students often choose formula without checking whether the point is axial, equatorial, or a general point.
Difficulty: Medium-Difficult
Concept Tested: Properties of magnetic field lines
Detailed Explanation: If two field lines intersect, there would be two directions of magnetic field at the same point, which is impossible.
Common trap: Students often choose formula without checking whether the point is axial, equatorial, or a general point.
JEE Main Question 9For a short bar magnet, the magnetic field at an axial point and equatorial point at the same distance are in the ratio
A) 1 : 1
B) 2 : 1
C) 1 : 2
D) 4 : 1
Correct Answer: B
Difficulty: Medium-Difficult
Concept Tested: Axial and equatorial field comparison
Detailed Explanation: For a short magnet, B_axial = (μ₀/4π)(2M/r³) and B_equatorial = (μ₀/4π)(M/r³). Hence ratio is 2:1.
Common trap: Students often choose formula without checking whether the point is axial, equatorial, or a general point.
Difficulty: Medium-Difficult
Concept Tested: Axial and equatorial field comparison
Detailed Explanation: For a short magnet, B_axial = (μ₀/4π)(2M/r³) and B_equatorial = (μ₀/4π)(M/r³). Hence ratio is 2:1.
Common trap: Students often choose formula without checking whether the point is axial, equatorial, or a general point.
JEE Main Question 10A bar magnet is broken into two equal pieces perpendicular to its length. Which statement is correct?
A) Each piece has only one pole
B) Magnetic monopoles are formed
C) Each piece is a complete magnet
D) Magnetic moment becomes zero
Correct Answer: C
Difficulty: Medium-Difficult
Concept Tested: Broken magnet
Detailed Explanation: Every broken piece again has north and south poles. Magnetic monopoles are not produced by breaking a magnet.
Common trap: Students often choose formula without checking whether the point is axial, equatorial, or a general point.
Difficulty: Medium-Difficult
Concept Tested: Broken magnet
Detailed Explanation: Every broken piece again has north and south poles. Magnetic monopoles are not produced by breaking a magnet.
Common trap: Students often choose formula without checking whether the point is axial, equatorial, or a general point.
JEE Main Question 11Net magnetic flux through any closed surface is
A) μ₀ times magnetic pole inside
B) zero
C) BA always
D) infinite for a bar magnet
Correct Answer: B
Difficulty: Medium-Difficult
Concept Tested: Gauss law of magnetism
Detailed Explanation: Gauss law of magnetism gives ∮B·dA = 0 because magnetic monopoles do not exist.
Common trap: Students often choose formula without checking whether the point is axial, equatorial, or a general point.
Difficulty: Medium-Difficult
Concept Tested: Gauss law of magnetism
Detailed Explanation: Gauss law of magnetism gives ∮B·dA = 0 because magnetic monopoles do not exist.
Common trap: Students often choose formula without checking whether the point is axial, equatorial, or a general point.
JEE Main Question 12A magnetic dipole is in stable equilibrium when angle between M and B is
A) 0°
B) 90°
C) 180°
D) 270°
Correct Answer: A
Difficulty: Medium-Difficult
Concept Tested: Magnetic potential energy
Detailed Explanation: Potential energy U = -MB cosθ is minimum at θ = 0°, so equilibrium is stable.
Common trap: Students often choose formula without checking whether the point is axial, equatorial, or a general point.
Difficulty: Medium-Difficult
Concept Tested: Magnetic potential energy
Detailed Explanation: Potential energy U = -MB cosθ is minimum at θ = 0°, so equilibrium is stable.
Common trap: Students often choose formula without checking whether the point is axial, equatorial, or a general point.
JEE Main Question 13Torque on a magnetic dipole in uniform magnetic field is maximum when θ is
A) 0°
B) 45°
C) 90°
D) 180°
Correct Answer: C
Difficulty: Medium-Difficult
Concept Tested: Torque on dipole
Detailed Explanation: τ = MB sinθ is maximum when sinθ = 1, i.e. θ = 90°.
Common trap: Students often choose formula without checking whether the point is axial, equatorial, or a general point.
Difficulty: Medium-Difficult
Concept Tested: Torque on dipole
Detailed Explanation: τ = MB sinθ is maximum when sinθ = 1, i.e. θ = 90°.
Common trap: Students often choose formula without checking whether the point is axial, equatorial, or a general point.
JEE Main Question 14Direction of magnetic moment of a bar magnet is
A) N to S outside the magnet
B) S to N inside the magnet
C) Always downward
D) Opposite to magnetic field lines everywhere
Correct Answer: B
Difficulty: Medium-Difficult
Concept Tested: Magnetic moment direction
Detailed Explanation: Magnetic moment vector is directed from south pole to north pole inside the magnet.
Common trap: Students often choose formula without checking whether the point is axial, equatorial, or a general point.
Difficulty: Medium-Difficult
Concept Tested: Magnetic moment direction
Detailed Explanation: Magnetic moment vector is directed from south pole to north pole inside the magnet.
Common trap: Students often choose formula without checking whether the point is axial, equatorial, or a general point.
JEE Main Question 15If distance from a short magnet is doubled, axial magnetic field becomes
A) 1/2
B) 1/4
C) 1/8
D) 1/16
Correct Answer: C
Difficulty: Medium-Difficult
Concept Tested: Short magnet inverse-cube law
Detailed Explanation: For a short magnet, B_axial ∝ 1/r³. Doubling r makes field 1/8.
Common trap: Students often choose formula without checking whether the point is axial, equatorial, or a general point.
Difficulty: Medium-Difficult
Concept Tested: Short magnet inverse-cube law
Detailed Explanation: For a short magnet, B_axial ∝ 1/r³. Doubling r makes field 1/8.
Common trap: Students often choose formula without checking whether the point is axial, equatorial, or a general point.
JEE Main Question 16Magnetic field lines never intersect because
A) they are imaginary
B) magnetic field has unique direction at a point
C) monopoles exist
D) field is scalar
Correct Answer: B
Difficulty: Medium-Difficult
Concept Tested: Properties of magnetic field lines
Detailed Explanation: If two field lines intersect, there would be two directions of magnetic field at the same point, which is impossible.
Common trap: Students often choose formula without checking whether the point is axial, equatorial, or a general point.
Difficulty: Medium-Difficult
Concept Tested: Properties of magnetic field lines
Detailed Explanation: If two field lines intersect, there would be two directions of magnetic field at the same point, which is impossible.
Common trap: Students often choose formula without checking whether the point is axial, equatorial, or a general point.
JEE Main Question 17For a short bar magnet, the magnetic field at an axial point and equatorial point at the same distance are in the ratio
A) 1 : 1
B) 2 : 1
C) 1 : 2
D) 4 : 1
Correct Answer: B
Difficulty: Medium-Difficult
Concept Tested: Axial and equatorial field comparison
Detailed Explanation: For a short magnet, B_axial = (μ₀/4π)(2M/r³) and B_equatorial = (μ₀/4π)(M/r³). Hence ratio is 2:1.
Common trap: Students often choose formula without checking whether the point is axial, equatorial, or a general point.
Difficulty: Medium-Difficult
Concept Tested: Axial and equatorial field comparison
Detailed Explanation: For a short magnet, B_axial = (μ₀/4π)(2M/r³) and B_equatorial = (μ₀/4π)(M/r³). Hence ratio is 2:1.
Common trap: Students often choose formula without checking whether the point is axial, equatorial, or a general point.
JEE Main Question 18A bar magnet is broken into two equal pieces perpendicular to its length. Which statement is correct?
A) Each piece has only one pole
B) Magnetic monopoles are formed
C) Each piece is a complete magnet
D) Magnetic moment becomes zero
Correct Answer: C
Difficulty: Medium-Difficult
Concept Tested: Broken magnet
Detailed Explanation: Every broken piece again has north and south poles. Magnetic monopoles are not produced by breaking a magnet.
Common trap: Students often choose formula without checking whether the point is axial, equatorial, or a general point.
Difficulty: Medium-Difficult
Concept Tested: Broken magnet
Detailed Explanation: Every broken piece again has north and south poles. Magnetic monopoles are not produced by breaking a magnet.
Common trap: Students often choose formula without checking whether the point is axial, equatorial, or a general point.
JEE Main Question 19Net magnetic flux through any closed surface is
A) μ₀ times magnetic pole inside
B) zero
C) BA always
D) infinite for a bar magnet
Correct Answer: B
Difficulty: Medium-Difficult
Concept Tested: Gauss law of magnetism
Detailed Explanation: Gauss law of magnetism gives ∮B·dA = 0 because magnetic monopoles do not exist.
Common trap: Students often choose formula without checking whether the point is axial, equatorial, or a general point.
Difficulty: Medium-Difficult
Concept Tested: Gauss law of magnetism
Detailed Explanation: Gauss law of magnetism gives ∮B·dA = 0 because magnetic monopoles do not exist.
Common trap: Students often choose formula without checking whether the point is axial, equatorial, or a general point.
JEE Main Question 20A magnetic dipole is in stable equilibrium when angle between M and B is
A) 0°
B) 90°
C) 180°
D) 270°
Correct Answer: A
Difficulty: Medium-Difficult
Concept Tested: Magnetic potential energy
Detailed Explanation: Potential energy U = -MB cosθ is minimum at θ = 0°, so equilibrium is stable.
Common trap: Students often choose formula without checking whether the point is axial, equatorial, or a general point.
Difficulty: Medium-Difficult
Concept Tested: Magnetic potential energy
Detailed Explanation: Potential energy U = -MB cosθ is minimum at θ = 0°, so equilibrium is stable.
Common trap: Students often choose formula without checking whether the point is axial, equatorial, or a general point.
JEE Main Question 21Torque on a magnetic dipole in uniform magnetic field is maximum when θ is
A) 0°
B) 45°
C) 90°
D) 180°
Correct Answer: C
Difficulty: Medium-Difficult
Concept Tested: Torque on dipole
Detailed Explanation: τ = MB sinθ is maximum when sinθ = 1, i.e. θ = 90°.
Common trap: Students often choose formula without checking whether the point is axial, equatorial, or a general point.
Difficulty: Medium-Difficult
Concept Tested: Torque on dipole
Detailed Explanation: τ = MB sinθ is maximum when sinθ = 1, i.e. θ = 90°.
Common trap: Students often choose formula without checking whether the point is axial, equatorial, or a general point.
JEE Main Question 22Direction of magnetic moment of a bar magnet is
A) N to S outside the magnet
B) S to N inside the magnet
C) Always downward
D) Opposite to magnetic field lines everywhere
Correct Answer: B
Difficulty: Medium-Difficult
Concept Tested: Magnetic moment direction
Detailed Explanation: Magnetic moment vector is directed from south pole to north pole inside the magnet.
Common trap: Students often choose formula without checking whether the point is axial, equatorial, or a general point.
Difficulty: Medium-Difficult
Concept Tested: Magnetic moment direction
Detailed Explanation: Magnetic moment vector is directed from south pole to north pole inside the magnet.
Common trap: Students often choose formula without checking whether the point is axial, equatorial, or a general point.
JEE Main Question 23If distance from a short magnet is doubled, axial magnetic field becomes
A) 1/2
B) 1/4
C) 1/8
D) 1/16
Correct Answer: C
Difficulty: Medium-Difficult
Concept Tested: Short magnet inverse-cube law
Detailed Explanation: For a short magnet, B_axial ∝ 1/r³. Doubling r makes field 1/8.
Common trap: Students often choose formula without checking whether the point is axial, equatorial, or a general point.
Difficulty: Medium-Difficult
Concept Tested: Short magnet inverse-cube law
Detailed Explanation: For a short magnet, B_axial ∝ 1/r³. Doubling r makes field 1/8.
Common trap: Students often choose formula without checking whether the point is axial, equatorial, or a general point.
JEE Main Question 24Magnetic field lines never intersect because
A) they are imaginary
B) magnetic field has unique direction at a point
C) monopoles exist
D) field is scalar
Correct Answer: B
Difficulty: Medium-Difficult
Concept Tested: Properties of magnetic field lines
Detailed Explanation: If two field lines intersect, there would be two directions of magnetic field at the same point, which is impossible.
Common trap: Students often choose formula without checking whether the point is axial, equatorial, or a general point.
Difficulty: Medium-Difficult
Concept Tested: Properties of magnetic field lines
Detailed Explanation: If two field lines intersect, there would be two directions of magnetic field at the same point, which is impossible.
Common trap: Students often choose formula without checking whether the point is axial, equatorial, or a general point.
JEE Main Question 25For a short bar magnet, the magnetic field at an axial point and equatorial point at the same distance are in the ratio
A) 1 : 1
B) 2 : 1
C) 1 : 2
D) 4 : 1
Correct Answer: B
Difficulty: Medium-Difficult
Concept Tested: Axial and equatorial field comparison
Detailed Explanation: For a short magnet, B_axial = (μ₀/4π)(2M/r³) and B_equatorial = (μ₀/4π)(M/r³). Hence ratio is 2:1.
Common trap: Students often choose formula without checking whether the point is axial, equatorial, or a general point.
Difficulty: Medium-Difficult
Concept Tested: Axial and equatorial field comparison
Detailed Explanation: For a short magnet, B_axial = (μ₀/4π)(2M/r³) and B_equatorial = (μ₀/4π)(M/r³). Hence ratio is 2:1.
Common trap: Students often choose formula without checking whether the point is axial, equatorial, or a general point.
JEE Main Question 26A bar magnet is broken into two equal pieces perpendicular to its length. Which statement is correct?
A) Each piece has only one pole
B) Magnetic monopoles are formed
C) Each piece is a complete magnet
D) Magnetic moment becomes zero
Correct Answer: C
Difficulty: Medium-Difficult
Concept Tested: Broken magnet
Detailed Explanation: Every broken piece again has north and south poles. Magnetic monopoles are not produced by breaking a magnet.
Common trap: Students often choose formula without checking whether the point is axial, equatorial, or a general point.
Difficulty: Medium-Difficult
Concept Tested: Broken magnet
Detailed Explanation: Every broken piece again has north and south poles. Magnetic monopoles are not produced by breaking a magnet.
Common trap: Students often choose formula without checking whether the point is axial, equatorial, or a general point.
JEE Main Question 27Net magnetic flux through any closed surface is
A) μ₀ times magnetic pole inside
B) zero
C) BA always
D) infinite for a bar magnet
Correct Answer: B
Difficulty: Medium-Difficult
Concept Tested: Gauss law of magnetism
Detailed Explanation: Gauss law of magnetism gives ∮B·dA = 0 because magnetic monopoles do not exist.
Common trap: Students often choose formula without checking whether the point is axial, equatorial, or a general point.
Difficulty: Medium-Difficult
Concept Tested: Gauss law of magnetism
Detailed Explanation: Gauss law of magnetism gives ∮B·dA = 0 because magnetic monopoles do not exist.
Common trap: Students often choose formula without checking whether the point is axial, equatorial, or a general point.
JEE Main Question 28A magnetic dipole is in stable equilibrium when angle between M and B is
A) 0°
B) 90°
C) 180°
D) 270°
Correct Answer: A
Difficulty: Medium-Difficult
Concept Tested: Magnetic potential energy
Detailed Explanation: Potential energy U = -MB cosθ is minimum at θ = 0°, so equilibrium is stable.
Common trap: Students often choose formula without checking whether the point is axial, equatorial, or a general point.
Difficulty: Medium-Difficult
Concept Tested: Magnetic potential energy
Detailed Explanation: Potential energy U = -MB cosθ is minimum at θ = 0°, so equilibrium is stable.
Common trap: Students often choose formula without checking whether the point is axial, equatorial, or a general point.
JEE Main Question 29Torque on a magnetic dipole in uniform magnetic field is maximum when θ is
A) 0°
B) 45°
C) 90°
D) 180°
Correct Answer: C
Difficulty: Medium-Difficult
Concept Tested: Torque on dipole
Detailed Explanation: τ = MB sinθ is maximum when sinθ = 1, i.e. θ = 90°.
Common trap: Students often choose formula without checking whether the point is axial, equatorial, or a general point.
Difficulty: Medium-Difficult
Concept Tested: Torque on dipole
Detailed Explanation: τ = MB sinθ is maximum when sinθ = 1, i.e. θ = 90°.
Common trap: Students often choose formula without checking whether the point is axial, equatorial, or a general point.
JEE Main Question 30Direction of magnetic moment of a bar magnet is
A) N to S outside the magnet
B) S to N inside the magnet
C) Always downward
D) Opposite to magnetic field lines everywhere
Correct Answer: B
Difficulty: Medium-Difficult
Concept Tested: Magnetic moment direction
Detailed Explanation: Magnetic moment vector is directed from south pole to north pole inside the magnet.
Common trap: Students often choose formula without checking whether the point is axial, equatorial, or a general point.
Difficulty: Medium-Difficult
Concept Tested: Magnetic moment direction
Detailed Explanation: Magnetic moment vector is directed from south pole to north pole inside the magnet.
Common trap: Students often choose formula without checking whether the point is axial, equatorial, or a general point.
JEE Main Question 31If distance from a short magnet is doubled, axial magnetic field becomes
A) 1/2
B) 1/4
C) 1/8
D) 1/16
Correct Answer: C
Difficulty: Medium-Difficult
Concept Tested: Short magnet inverse-cube law
Detailed Explanation: For a short magnet, B_axial ∝ 1/r³. Doubling r makes field 1/8.
Common trap: Students often choose formula without checking whether the point is axial, equatorial, or a general point.
Difficulty: Medium-Difficult
Concept Tested: Short magnet inverse-cube law
Detailed Explanation: For a short magnet, B_axial ∝ 1/r³. Doubling r makes field 1/8.
Common trap: Students often choose formula without checking whether the point is axial, equatorial, or a general point.
JEE Main Question 32Magnetic field lines never intersect because
A) they are imaginary
B) magnetic field has unique direction at a point
C) monopoles exist
D) field is scalar
Correct Answer: B
Difficulty: Medium-Difficult
Concept Tested: Properties of magnetic field lines
Detailed Explanation: If two field lines intersect, there would be two directions of magnetic field at the same point, which is impossible.
Common trap: Students often choose formula without checking whether the point is axial, equatorial, or a general point.
Difficulty: Medium-Difficult
Concept Tested: Properties of magnetic field lines
Detailed Explanation: If two field lines intersect, there would be two directions of magnetic field at the same point, which is impossible.
Common trap: Students often choose formula without checking whether the point is axial, equatorial, or a general point.
JEE Main Question 33For a short bar magnet, the magnetic field at an axial point and equatorial point at the same distance are in the ratio
A) 1 : 1
B) 2 : 1
C) 1 : 2
D) 4 : 1
Correct Answer: B
Difficulty: Medium-Difficult
Concept Tested: Axial and equatorial field comparison
Detailed Explanation: For a short magnet, B_axial = (μ₀/4π)(2M/r³) and B_equatorial = (μ₀/4π)(M/r³). Hence ratio is 2:1.
Common trap: Students often choose formula without checking whether the point is axial, equatorial, or a general point.
Difficulty: Medium-Difficult
Concept Tested: Axial and equatorial field comparison
Detailed Explanation: For a short magnet, B_axial = (μ₀/4π)(2M/r³) and B_equatorial = (μ₀/4π)(M/r³). Hence ratio is 2:1.
Common trap: Students often choose formula without checking whether the point is axial, equatorial, or a general point.
JEE Main Question 34A bar magnet is broken into two equal pieces perpendicular to its length. Which statement is correct?
A) Each piece has only one pole
B) Magnetic monopoles are formed
C) Each piece is a complete magnet
D) Magnetic moment becomes zero
Correct Answer: C
Difficulty: Medium-Difficult
Concept Tested: Broken magnet
Detailed Explanation: Every broken piece again has north and south poles. Magnetic monopoles are not produced by breaking a magnet.
Common trap: Students often choose formula without checking whether the point is axial, equatorial, or a general point.
Difficulty: Medium-Difficult
Concept Tested: Broken magnet
Detailed Explanation: Every broken piece again has north and south poles. Magnetic monopoles are not produced by breaking a magnet.
Common trap: Students often choose formula without checking whether the point is axial, equatorial, or a general point.
JEE Main Question 35Net magnetic flux through any closed surface is
A) μ₀ times magnetic pole inside
B) zero
C) BA always
D) infinite for a bar magnet
Correct Answer: B
Difficulty: Medium-Difficult
Concept Tested: Gauss law of magnetism
Detailed Explanation: Gauss law of magnetism gives ∮B·dA = 0 because magnetic monopoles do not exist.
Common trap: Students often choose formula without checking whether the point is axial, equatorial, or a general point.
Difficulty: Medium-Difficult
Concept Tested: Gauss law of magnetism
Detailed Explanation: Gauss law of magnetism gives ∮B·dA = 0 because magnetic monopoles do not exist.
Common trap: Students often choose formula without checking whether the point is axial, equatorial, or a general point.
JEE Main Question 36A magnetic dipole is in stable equilibrium when angle between M and B is
A) 0°
B) 90°
C) 180°
D) 270°
Correct Answer: A
Difficulty: Medium-Difficult
Concept Tested: Magnetic potential energy
Detailed Explanation: Potential energy U = -MB cosθ is minimum at θ = 0°, so equilibrium is stable.
Common trap: Students often choose formula without checking whether the point is axial, equatorial, or a general point.
Difficulty: Medium-Difficult
Concept Tested: Magnetic potential energy
Detailed Explanation: Potential energy U = -MB cosθ is minimum at θ = 0°, so equilibrium is stable.
Common trap: Students often choose formula without checking whether the point is axial, equatorial, or a general point.
JEE Main Question 37Torque on a magnetic dipole in uniform magnetic field is maximum when θ is
A) 0°
B) 45°
C) 90°
D) 180°
Correct Answer: C
Difficulty: Medium-Difficult
Concept Tested: Torque on dipole
Detailed Explanation: τ = MB sinθ is maximum when sinθ = 1, i.e. θ = 90°.
Common trap: Students often choose formula without checking whether the point is axial, equatorial, or a general point.
Difficulty: Medium-Difficult
Concept Tested: Torque on dipole
Detailed Explanation: τ = MB sinθ is maximum when sinθ = 1, i.e. θ = 90°.
Common trap: Students often choose formula without checking whether the point is axial, equatorial, or a general point.
JEE Main Question 38Direction of magnetic moment of a bar magnet is
A) N to S outside the magnet
B) S to N inside the magnet
C) Always downward
D) Opposite to magnetic field lines everywhere
Correct Answer: B
Difficulty: Medium-Difficult
Concept Tested: Magnetic moment direction
Detailed Explanation: Magnetic moment vector is directed from south pole to north pole inside the magnet.
Common trap: Students often choose formula without checking whether the point is axial, equatorial, or a general point.
Difficulty: Medium-Difficult
Concept Tested: Magnetic moment direction
Detailed Explanation: Magnetic moment vector is directed from south pole to north pole inside the magnet.
Common trap: Students often choose formula without checking whether the point is axial, equatorial, or a general point.
JEE Main Question 39If distance from a short magnet is doubled, axial magnetic field becomes
A) 1/2
B) 1/4
C) 1/8
D) 1/16
Correct Answer: C
Difficulty: Medium-Difficult
Concept Tested: Short magnet inverse-cube law
Detailed Explanation: For a short magnet, B_axial ∝ 1/r³. Doubling r makes field 1/8.
Common trap: Students often choose formula without checking whether the point is axial, equatorial, or a general point.
Difficulty: Medium-Difficult
Concept Tested: Short magnet inverse-cube law
Detailed Explanation: For a short magnet, B_axial ∝ 1/r³. Doubling r makes field 1/8.
Common trap: Students often choose formula without checking whether the point is axial, equatorial, or a general point.
JEE Main Question 40Magnetic field lines never intersect because
A) they are imaginary
B) magnetic field has unique direction at a point
C) monopoles exist
D) field is scalar
Correct Answer: B
Difficulty: Medium-Difficult
Concept Tested: Properties of magnetic field lines
Detailed Explanation: If two field lines intersect, there would be two directions of magnetic field at the same point, which is impossible.
Common trap: Students often choose formula without checking whether the point is axial, equatorial, or a general point.
Difficulty: Medium-Difficult
Concept Tested: Properties of magnetic field lines
Detailed Explanation: If two field lines intersect, there would be two directions of magnetic field at the same point, which is impossible.
Common trap: Students often choose formula without checking whether the point is axial, equatorial, or a general point.
JEE Main Question 41For a short bar magnet, the magnetic field at an axial point and equatorial point at the same distance are in the ratio
A) 1 : 1
B) 2 : 1
C) 1 : 2
D) 4 : 1
Correct Answer: B
Difficulty: Medium-Difficult
Concept Tested: Axial and equatorial field comparison
Detailed Explanation: For a short magnet, B_axial = (μ₀/4π)(2M/r³) and B_equatorial = (μ₀/4π)(M/r³). Hence ratio is 2:1.
Common trap: Students often choose formula without checking whether the point is axial, equatorial, or a general point.
Difficulty: Medium-Difficult
Concept Tested: Axial and equatorial field comparison
Detailed Explanation: For a short magnet, B_axial = (μ₀/4π)(2M/r³) and B_equatorial = (μ₀/4π)(M/r³). Hence ratio is 2:1.
Common trap: Students often choose formula without checking whether the point is axial, equatorial, or a general point.
JEE Main Question 42A bar magnet is broken into two equal pieces perpendicular to its length. Which statement is correct?
A) Each piece has only one pole
B) Magnetic monopoles are formed
C) Each piece is a complete magnet
D) Magnetic moment becomes zero
Correct Answer: C
Difficulty: Medium-Difficult
Concept Tested: Broken magnet
Detailed Explanation: Every broken piece again has north and south poles. Magnetic monopoles are not produced by breaking a magnet.
Common trap: Students often choose formula without checking whether the point is axial, equatorial, or a general point.
Difficulty: Medium-Difficult
Concept Tested: Broken magnet
Detailed Explanation: Every broken piece again has north and south poles. Magnetic monopoles are not produced by breaking a magnet.
Common trap: Students often choose formula without checking whether the point is axial, equatorial, or a general point.
JEE Main Question 43Net magnetic flux through any closed surface is
A) μ₀ times magnetic pole inside
B) zero
C) BA always
D) infinite for a bar magnet
Correct Answer: B
Difficulty: Medium-Difficult
Concept Tested: Gauss law of magnetism
Detailed Explanation: Gauss law of magnetism gives ∮B·dA = 0 because magnetic monopoles do not exist.
Common trap: Students often choose formula without checking whether the point is axial, equatorial, or a general point.
Difficulty: Medium-Difficult
Concept Tested: Gauss law of magnetism
Detailed Explanation: Gauss law of magnetism gives ∮B·dA = 0 because magnetic monopoles do not exist.
Common trap: Students often choose formula without checking whether the point is axial, equatorial, or a general point.
JEE Main Question 44A magnetic dipole is in stable equilibrium when angle between M and B is
A) 0°
B) 90°
C) 180°
D) 270°
Correct Answer: A
Difficulty: Medium-Difficult
Concept Tested: Magnetic potential energy
Detailed Explanation: Potential energy U = -MB cosθ is minimum at θ = 0°, so equilibrium is stable.
Common trap: Students often choose formula without checking whether the point is axial, equatorial, or a general point.
Difficulty: Medium-Difficult
Concept Tested: Magnetic potential energy
Detailed Explanation: Potential energy U = -MB cosθ is minimum at θ = 0°, so equilibrium is stable.
Common trap: Students often choose formula without checking whether the point is axial, equatorial, or a general point.
JEE Main Question 45Torque on a magnetic dipole in uniform magnetic field is maximum when θ is
A) 0°
B) 45°
C) 90°
D) 180°
Correct Answer: C
Difficulty: Medium-Difficult
Concept Tested: Torque on dipole
Detailed Explanation: τ = MB sinθ is maximum when sinθ = 1, i.e. θ = 90°.
Common trap: Students often choose formula without checking whether the point is axial, equatorial, or a general point.
Difficulty: Medium-Difficult
Concept Tested: Torque on dipole
Detailed Explanation: τ = MB sinθ is maximum when sinθ = 1, i.e. θ = 90°.
Common trap: Students often choose formula without checking whether the point is axial, equatorial, or a general point.
JEE Main Question 46Direction of magnetic moment of a bar magnet is
A) N to S outside the magnet
B) S to N inside the magnet
C) Always downward
D) Opposite to magnetic field lines everywhere
Correct Answer: B
Difficulty: Medium-Difficult
Concept Tested: Magnetic moment direction
Detailed Explanation: Magnetic moment vector is directed from south pole to north pole inside the magnet.
Common trap: Students often choose formula without checking whether the point is axial, equatorial, or a general point.
Difficulty: Medium-Difficult
Concept Tested: Magnetic moment direction
Detailed Explanation: Magnetic moment vector is directed from south pole to north pole inside the magnet.
Common trap: Students often choose formula without checking whether the point is axial, equatorial, or a general point.
JEE Main Question 47If distance from a short magnet is doubled, axial magnetic field becomes
A) 1/2
B) 1/4
C) 1/8
D) 1/16
Correct Answer: C
Difficulty: Medium-Difficult
Concept Tested: Short magnet inverse-cube law
Detailed Explanation: For a short magnet, B_axial ∝ 1/r³. Doubling r makes field 1/8.
Common trap: Students often choose formula without checking whether the point is axial, equatorial, or a general point.
Difficulty: Medium-Difficult
Concept Tested: Short magnet inverse-cube law
Detailed Explanation: For a short magnet, B_axial ∝ 1/r³. Doubling r makes field 1/8.
Common trap: Students often choose formula without checking whether the point is axial, equatorial, or a general point.
JEE Main Question 48Magnetic field lines never intersect because
A) they are imaginary
B) magnetic field has unique direction at a point
C) monopoles exist
D) field is scalar
Correct Answer: B
Difficulty: Medium-Difficult
Concept Tested: Properties of magnetic field lines
Detailed Explanation: If two field lines intersect, there would be two directions of magnetic field at the same point, which is impossible.
Common trap: Students often choose formula without checking whether the point is axial, equatorial, or a general point.
Difficulty: Medium-Difficult
Concept Tested: Properties of magnetic field lines
Detailed Explanation: If two field lines intersect, there would be two directions of magnetic field at the same point, which is impossible.
Common trap: Students often choose formula without checking whether the point is axial, equatorial, or a general point.
JEE Main Question 49For a short bar magnet, the magnetic field at an axial point and equatorial point at the same distance are in the ratio
A) 1 : 1
B) 2 : 1
C) 1 : 2
D) 4 : 1
Correct Answer: B
Difficulty: Medium-Difficult
Concept Tested: Axial and equatorial field comparison
Detailed Explanation: For a short magnet, B_axial = (μ₀/4π)(2M/r³) and B_equatorial = (μ₀/4π)(M/r³). Hence ratio is 2:1.
Common trap: Students often choose formula without checking whether the point is axial, equatorial, or a general point.
Difficulty: Medium-Difficult
Concept Tested: Axial and equatorial field comparison
Detailed Explanation: For a short magnet, B_axial = (μ₀/4π)(2M/r³) and B_equatorial = (μ₀/4π)(M/r³). Hence ratio is 2:1.
Common trap: Students often choose formula without checking whether the point is axial, equatorial, or a general point.
JEE Main Question 50A bar magnet is broken into two equal pieces perpendicular to its length. Which statement is correct?
A) Each piece has only one pole
B) Magnetic monopoles are formed
C) Each piece is a complete magnet
D) Magnetic moment becomes zero
Correct Answer: C
Difficulty: Medium-Difficult
Concept Tested: Broken magnet
Detailed Explanation: Every broken piece again has north and south poles. Magnetic monopoles are not produced by breaking a magnet.
Common trap: Students often choose formula without checking whether the point is axial, equatorial, or a general point.
Difficulty: Medium-Difficult
Concept Tested: Broken magnet
Detailed Explanation: Every broken piece again has north and south poles. Magnetic monopoles are not produced by breaking a magnet.
Common trap: Students often choose formula without checking whether the point is axial, equatorial, or a general point.
JEE Main Question 51Net magnetic flux through any closed surface is
A) μ₀ times magnetic pole inside
B) zero
C) BA always
D) infinite for a bar magnet
Correct Answer: B
Difficulty: Medium-Difficult
Concept Tested: Gauss law of magnetism
Detailed Explanation: Gauss law of magnetism gives ∮B·dA = 0 because magnetic monopoles do not exist.
Common trap: Students often choose formula without checking whether the point is axial, equatorial, or a general point.
Difficulty: Medium-Difficult
Concept Tested: Gauss law of magnetism
Detailed Explanation: Gauss law of magnetism gives ∮B·dA = 0 because magnetic monopoles do not exist.
Common trap: Students often choose formula without checking whether the point is axial, equatorial, or a general point.
JEE Main Question 52A magnetic dipole is in stable equilibrium when angle between M and B is
A) 0°
B) 90°
C) 180°
D) 270°
Correct Answer: A
Difficulty: Medium-Difficult
Concept Tested: Magnetic potential energy
Detailed Explanation: Potential energy U = -MB cosθ is minimum at θ = 0°, so equilibrium is stable.
Common trap: Students often choose formula without checking whether the point is axial, equatorial, or a general point.
Difficulty: Medium-Difficult
Concept Tested: Magnetic potential energy
Detailed Explanation: Potential energy U = -MB cosθ is minimum at θ = 0°, so equilibrium is stable.
Common trap: Students often choose formula without checking whether the point is axial, equatorial, or a general point.
JEE Main Question 53Torque on a magnetic dipole in uniform magnetic field is maximum when θ is
A) 0°
B) 45°
C) 90°
D) 180°
Correct Answer: C
Difficulty: Medium-Difficult
Concept Tested: Torque on dipole
Detailed Explanation: τ = MB sinθ is maximum when sinθ = 1, i.e. θ = 90°.
Common trap: Students often choose formula without checking whether the point is axial, equatorial, or a general point.
Difficulty: Medium-Difficult
Concept Tested: Torque on dipole
Detailed Explanation: τ = MB sinθ is maximum when sinθ = 1, i.e. θ = 90°.
Common trap: Students often choose formula without checking whether the point is axial, equatorial, or a general point.
JEE Main Question 54Direction of magnetic moment of a bar magnet is
A) N to S outside the magnet
B) S to N inside the magnet
C) Always downward
D) Opposite to magnetic field lines everywhere
Correct Answer: B
Difficulty: Medium-Difficult
Concept Tested: Magnetic moment direction
Detailed Explanation: Magnetic moment vector is directed from south pole to north pole inside the magnet.
Common trap: Students often choose formula without checking whether the point is axial, equatorial, or a general point.
Difficulty: Medium-Difficult
Concept Tested: Magnetic moment direction
Detailed Explanation: Magnetic moment vector is directed from south pole to north pole inside the magnet.
Common trap: Students often choose formula without checking whether the point is axial, equatorial, or a general point.
JEE Main Question 55If distance from a short magnet is doubled, axial magnetic field becomes
A) 1/2
B) 1/4
C) 1/8
D) 1/16
Correct Answer: C
Difficulty: Medium-Difficult
Concept Tested: Short magnet inverse-cube law
Detailed Explanation: For a short magnet, B_axial ∝ 1/r³. Doubling r makes field 1/8.
Common trap: Students often choose formula without checking whether the point is axial, equatorial, or a general point.
Difficulty: Medium-Difficult
Concept Tested: Short magnet inverse-cube law
Detailed Explanation: For a short magnet, B_axial ∝ 1/r³. Doubling r makes field 1/8.
Common trap: Students often choose formula without checking whether the point is axial, equatorial, or a general point.
JEE Main Question 56Magnetic field lines never intersect because
A) they are imaginary
B) magnetic field has unique direction at a point
C) monopoles exist
D) field is scalar
Correct Answer: B
Difficulty: Medium-Difficult
Concept Tested: Properties of magnetic field lines
Detailed Explanation: If two field lines intersect, there would be two directions of magnetic field at the same point, which is impossible.
Common trap: Students often choose formula without checking whether the point is axial, equatorial, or a general point.
Difficulty: Medium-Difficult
Concept Tested: Properties of magnetic field lines
Detailed Explanation: If two field lines intersect, there would be two directions of magnetic field at the same point, which is impossible.
Common trap: Students often choose formula without checking whether the point is axial, equatorial, or a general point.
JEE Main Question 57For a short bar magnet, the magnetic field at an axial point and equatorial point at the same distance are in the ratio
A) 1 : 1
B) 2 : 1
C) 1 : 2
D) 4 : 1
Correct Answer: B
Difficulty: Medium-Difficult
Concept Tested: Axial and equatorial field comparison
Detailed Explanation: For a short magnet, B_axial = (μ₀/4π)(2M/r³) and B_equatorial = (μ₀/4π)(M/r³). Hence ratio is 2:1.
Common trap: Students often choose formula without checking whether the point is axial, equatorial, or a general point.
Difficulty: Medium-Difficult
Concept Tested: Axial and equatorial field comparison
Detailed Explanation: For a short magnet, B_axial = (μ₀/4π)(2M/r³) and B_equatorial = (μ₀/4π)(M/r³). Hence ratio is 2:1.
Common trap: Students often choose formula without checking whether the point is axial, equatorial, or a general point.
JEE Main Question 58A bar magnet is broken into two equal pieces perpendicular to its length. Which statement is correct?
A) Each piece has only one pole
B) Magnetic monopoles are formed
C) Each piece is a complete magnet
D) Magnetic moment becomes zero
Correct Answer: C
Difficulty: Medium-Difficult
Concept Tested: Broken magnet
Detailed Explanation: Every broken piece again has north and south poles. Magnetic monopoles are not produced by breaking a magnet.
Common trap: Students often choose formula without checking whether the point is axial, equatorial, or a general point.
Difficulty: Medium-Difficult
Concept Tested: Broken magnet
Detailed Explanation: Every broken piece again has north and south poles. Magnetic monopoles are not produced by breaking a magnet.
Common trap: Students often choose formula without checking whether the point is axial, equatorial, or a general point.
JEE Main Question 59Net magnetic flux through any closed surface is
A) μ₀ times magnetic pole inside
B) zero
C) BA always
D) infinite for a bar magnet
Correct Answer: B
Difficulty: Medium-Difficult
Concept Tested: Gauss law of magnetism
Detailed Explanation: Gauss law of magnetism gives ∮B·dA = 0 because magnetic monopoles do not exist.
Common trap: Students often choose formula without checking whether the point is axial, equatorial, or a general point.
Difficulty: Medium-Difficult
Concept Tested: Gauss law of magnetism
Detailed Explanation: Gauss law of magnetism gives ∮B·dA = 0 because magnetic monopoles do not exist.
Common trap: Students often choose formula without checking whether the point is axial, equatorial, or a general point.
JEE Main Question 60A magnetic dipole is in stable equilibrium when angle between M and B is
A) 0°
B) 90°
C) 180°
D) 270°
Correct Answer: A
Difficulty: Medium-Difficult
Concept Tested: Magnetic potential energy
Detailed Explanation: Potential energy U = -MB cosθ is minimum at θ = 0°, so equilibrium is stable.
Common trap: Students often choose formula without checking whether the point is axial, equatorial, or a general point.
Difficulty: Medium-Difficult
Concept Tested: Magnetic potential energy
Detailed Explanation: Potential energy U = -MB cosθ is minimum at θ = 0°, so equilibrium is stable.
Common trap: Students often choose formula without checking whether the point is axial, equatorial, or a general point.
JEE Main Question 61Torque on a magnetic dipole in uniform magnetic field is maximum when θ is
A) 0°
B) 45°
C) 90°
D) 180°
Correct Answer: C
Difficulty: Medium-Difficult
Concept Tested: Torque on dipole
Detailed Explanation: τ = MB sinθ is maximum when sinθ = 1, i.e. θ = 90°.
Common trap: Students often choose formula without checking whether the point is axial, equatorial, or a general point.
Difficulty: Medium-Difficult
Concept Tested: Torque on dipole
Detailed Explanation: τ = MB sinθ is maximum when sinθ = 1, i.e. θ = 90°.
Common trap: Students often choose formula without checking whether the point is axial, equatorial, or a general point.
JEE Main Question 62Direction of magnetic moment of a bar magnet is
A) N to S outside the magnet
B) S to N inside the magnet
C) Always downward
D) Opposite to magnetic field lines everywhere
Correct Answer: B
Difficulty: Medium-Difficult
Concept Tested: Magnetic moment direction
Detailed Explanation: Magnetic moment vector is directed from south pole to north pole inside the magnet.
Common trap: Students often choose formula without checking whether the point is axial, equatorial, or a general point.
Difficulty: Medium-Difficult
Concept Tested: Magnetic moment direction
Detailed Explanation: Magnetic moment vector is directed from south pole to north pole inside the magnet.
Common trap: Students often choose formula without checking whether the point is axial, equatorial, or a general point.
JEE Main Question 63If distance from a short magnet is doubled, axial magnetic field becomes
A) 1/2
B) 1/4
C) 1/8
D) 1/16
Correct Answer: C
Difficulty: Medium-Difficult
Concept Tested: Short magnet inverse-cube law
Detailed Explanation: For a short magnet, B_axial ∝ 1/r³. Doubling r makes field 1/8.
Common trap: Students often choose formula without checking whether the point is axial, equatorial, or a general point.
Difficulty: Medium-Difficult
Concept Tested: Short magnet inverse-cube law
Detailed Explanation: For a short magnet, B_axial ∝ 1/r³. Doubling r makes field 1/8.
Common trap: Students often choose formula without checking whether the point is axial, equatorial, or a general point.
JEE Main Question 64Magnetic field lines never intersect because
A) they are imaginary
B) magnetic field has unique direction at a point
C) monopoles exist
D) field is scalar
Correct Answer: B
Difficulty: Medium-Difficult
Concept Tested: Properties of magnetic field lines
Detailed Explanation: If two field lines intersect, there would be two directions of magnetic field at the same point, which is impossible.
Common trap: Students often choose formula without checking whether the point is axial, equatorial, or a general point.
Difficulty: Medium-Difficult
Concept Tested: Properties of magnetic field lines
Detailed Explanation: If two field lines intersect, there would be two directions of magnetic field at the same point, which is impossible.
Common trap: Students often choose formula without checking whether the point is axial, equatorial, or a general point.
JEE Main Question 65For a short bar magnet, the magnetic field at an axial point and equatorial point at the same distance are in the ratio
A) 1 : 1
B) 2 : 1
C) 1 : 2
D) 4 : 1
Correct Answer: B
Difficulty: Medium-Difficult
Concept Tested: Axial and equatorial field comparison
Detailed Explanation: For a short magnet, B_axial = (μ₀/4π)(2M/r³) and B_equatorial = (μ₀/4π)(M/r³). Hence ratio is 2:1.
Common trap: Students often choose formula without checking whether the point is axial, equatorial, or a general point.
Difficulty: Medium-Difficult
Concept Tested: Axial and equatorial field comparison
Detailed Explanation: For a short magnet, B_axial = (μ₀/4π)(2M/r³) and B_equatorial = (μ₀/4π)(M/r³). Hence ratio is 2:1.
Common trap: Students often choose formula without checking whether the point is axial, equatorial, or a general point.
JEE Main Question 66A bar magnet is broken into two equal pieces perpendicular to its length. Which statement is correct?
A) Each piece has only one pole
B) Magnetic monopoles are formed
C) Each piece is a complete magnet
D) Magnetic moment becomes zero
Correct Answer: C
Difficulty: Medium-Difficult
Concept Tested: Broken magnet
Detailed Explanation: Every broken piece again has north and south poles. Magnetic monopoles are not produced by breaking a magnet.
Common trap: Students often choose formula without checking whether the point is axial, equatorial, or a general point.
Difficulty: Medium-Difficult
Concept Tested: Broken magnet
Detailed Explanation: Every broken piece again has north and south poles. Magnetic monopoles are not produced by breaking a magnet.
Common trap: Students often choose formula without checking whether the point is axial, equatorial, or a general point.
JEE Main Question 67Net magnetic flux through any closed surface is
A) μ₀ times magnetic pole inside
B) zero
C) BA always
D) infinite for a bar magnet
Correct Answer: B
Difficulty: Medium-Difficult
Concept Tested: Gauss law of magnetism
Detailed Explanation: Gauss law of magnetism gives ∮B·dA = 0 because magnetic monopoles do not exist.
Common trap: Students often choose formula without checking whether the point is axial, equatorial, or a general point.
Difficulty: Medium-Difficult
Concept Tested: Gauss law of magnetism
Detailed Explanation: Gauss law of magnetism gives ∮B·dA = 0 because magnetic monopoles do not exist.
Common trap: Students often choose formula without checking whether the point is axial, equatorial, or a general point.
JEE Main Question 68A magnetic dipole is in stable equilibrium when angle between M and B is
A) 0°
B) 90°
C) 180°
D) 270°
Correct Answer: A
Difficulty: Medium-Difficult
Concept Tested: Magnetic potential energy
Detailed Explanation: Potential energy U = -MB cosθ is minimum at θ = 0°, so equilibrium is stable.
Common trap: Students often choose formula without checking whether the point is axial, equatorial, or a general point.
Difficulty: Medium-Difficult
Concept Tested: Magnetic potential energy
Detailed Explanation: Potential energy U = -MB cosθ is minimum at θ = 0°, so equilibrium is stable.
Common trap: Students often choose formula without checking whether the point is axial, equatorial, or a general point.
JEE Main Question 69Torque on a magnetic dipole in uniform magnetic field is maximum when θ is
A) 0°
B) 45°
C) 90°
D) 180°
Correct Answer: C
Difficulty: Medium-Difficult
Concept Tested: Torque on dipole
Detailed Explanation: τ = MB sinθ is maximum when sinθ = 1, i.e. θ = 90°.
Common trap: Students often choose formula without checking whether the point is axial, equatorial, or a general point.
Difficulty: Medium-Difficult
Concept Tested: Torque on dipole
Detailed Explanation: τ = MB sinθ is maximum when sinθ = 1, i.e. θ = 90°.
Common trap: Students often choose formula without checking whether the point is axial, equatorial, or a general point.
JEE Main Question 70Direction of magnetic moment of a bar magnet is
A) N to S outside the magnet
B) S to N inside the magnet
C) Always downward
D) Opposite to magnetic field lines everywhere
Correct Answer: B
Difficulty: Medium-Difficult
Concept Tested: Magnetic moment direction
Detailed Explanation: Magnetic moment vector is directed from south pole to north pole inside the magnet.
Common trap: Students often choose formula without checking whether the point is axial, equatorial, or a general point.
Difficulty: Medium-Difficult
Concept Tested: Magnetic moment direction
Detailed Explanation: Magnetic moment vector is directed from south pole to north pole inside the magnet.
Common trap: Students often choose formula without checking whether the point is axial, equatorial, or a general point.
JEE Main Question 71If distance from a short magnet is doubled, axial magnetic field becomes
A) 1/2
B) 1/4
C) 1/8
D) 1/16
Correct Answer: C
Difficulty: Medium-Difficult
Concept Tested: Short magnet inverse-cube law
Detailed Explanation: For a short magnet, B_axial ∝ 1/r³. Doubling r makes field 1/8.
Common trap: Students often choose formula without checking whether the point is axial, equatorial, or a general point.
Difficulty: Medium-Difficult
Concept Tested: Short magnet inverse-cube law
Detailed Explanation: For a short magnet, B_axial ∝ 1/r³. Doubling r makes field 1/8.
Common trap: Students often choose formula without checking whether the point is axial, equatorial, or a general point.
JEE Main Question 72Magnetic field lines never intersect because
A) they are imaginary
B) magnetic field has unique direction at a point
C) monopoles exist
D) field is scalar
Correct Answer: B
Difficulty: Medium-Difficult
Concept Tested: Properties of magnetic field lines
Detailed Explanation: If two field lines intersect, there would be two directions of magnetic field at the same point, which is impossible.
Common trap: Students often choose formula without checking whether the point is axial, equatorial, or a general point.
Difficulty: Medium-Difficult
Concept Tested: Properties of magnetic field lines
Detailed Explanation: If two field lines intersect, there would be two directions of magnetic field at the same point, which is impossible.
Common trap: Students often choose formula without checking whether the point is axial, equatorial, or a general point.
JEE Main Question 73For a short bar magnet, the magnetic field at an axial point and equatorial point at the same distance are in the ratio
A) 1 : 1
B) 2 : 1
C) 1 : 2
D) 4 : 1
Correct Answer: B
Difficulty: Medium-Difficult
Concept Tested: Axial and equatorial field comparison
Detailed Explanation: For a short magnet, B_axial = (μ₀/4π)(2M/r³) and B_equatorial = (μ₀/4π)(M/r³). Hence ratio is 2:1.
Common trap: Students often choose formula without checking whether the point is axial, equatorial, or a general point.
Difficulty: Medium-Difficult
Concept Tested: Axial and equatorial field comparison
Detailed Explanation: For a short magnet, B_axial = (μ₀/4π)(2M/r³) and B_equatorial = (μ₀/4π)(M/r³). Hence ratio is 2:1.
Common trap: Students often choose formula without checking whether the point is axial, equatorial, or a general point.
JEE Main Question 74A bar magnet is broken into two equal pieces perpendicular to its length. Which statement is correct?
A) Each piece has only one pole
B) Magnetic monopoles are formed
C) Each piece is a complete magnet
D) Magnetic moment becomes zero
Correct Answer: C
Difficulty: Medium-Difficult
Concept Tested: Broken magnet
Detailed Explanation: Every broken piece again has north and south poles. Magnetic monopoles are not produced by breaking a magnet.
Common trap: Students often choose formula without checking whether the point is axial, equatorial, or a general point.
Difficulty: Medium-Difficult
Concept Tested: Broken magnet
Detailed Explanation: Every broken piece again has north and south poles. Magnetic monopoles are not produced by breaking a magnet.
Common trap: Students often choose formula without checking whether the point is axial, equatorial, or a general point.
JEE Main Question 75Net magnetic flux through any closed surface is
A) μ₀ times magnetic pole inside
B) zero
C) BA always
D) infinite for a bar magnet
Correct Answer: B
Difficulty: Medium-Difficult
Concept Tested: Gauss law of magnetism
Detailed Explanation: Gauss law of magnetism gives ∮B·dA = 0 because magnetic monopoles do not exist.
Common trap: Students often choose formula without checking whether the point is axial, equatorial, or a general point.
Difficulty: Medium-Difficult
Concept Tested: Gauss law of magnetism
Detailed Explanation: Gauss law of magnetism gives ∮B·dA = 0 because magnetic monopoles do not exist.
Common trap: Students often choose formula without checking whether the point is axial, equatorial, or a general point.
JEE Main Question 76A magnetic dipole is in stable equilibrium when angle between M and B is
A) 0°
B) 90°
C) 180°
D) 270°
Correct Answer: A
Difficulty: Medium-Difficult
Concept Tested: Magnetic potential energy
Detailed Explanation: Potential energy U = -MB cosθ is minimum at θ = 0°, so equilibrium is stable.
Common trap: Students often choose formula without checking whether the point is axial, equatorial, or a general point.
Difficulty: Medium-Difficult
Concept Tested: Magnetic potential energy
Detailed Explanation: Potential energy U = -MB cosθ is minimum at θ = 0°, so equilibrium is stable.
Common trap: Students often choose formula without checking whether the point is axial, equatorial, or a general point.
JEE Main Question 77Torque on a magnetic dipole in uniform magnetic field is maximum when θ is
A) 0°
B) 45°
C) 90°
D) 180°
Correct Answer: C
Difficulty: Medium-Difficult
Concept Tested: Torque on dipole
Detailed Explanation: τ = MB sinθ is maximum when sinθ = 1, i.e. θ = 90°.
Common trap: Students often choose formula without checking whether the point is axial, equatorial, or a general point.
Difficulty: Medium-Difficult
Concept Tested: Torque on dipole
Detailed Explanation: τ = MB sinθ is maximum when sinθ = 1, i.e. θ = 90°.
Common trap: Students often choose formula without checking whether the point is axial, equatorial, or a general point.
JEE Main Question 78Direction of magnetic moment of a bar magnet is
A) N to S outside the magnet
B) S to N inside the magnet
C) Always downward
D) Opposite to magnetic field lines everywhere
Correct Answer: B
Difficulty: Medium-Difficult
Concept Tested: Magnetic moment direction
Detailed Explanation: Magnetic moment vector is directed from south pole to north pole inside the magnet.
Common trap: Students often choose formula without checking whether the point is axial, equatorial, or a general point.
Difficulty: Medium-Difficult
Concept Tested: Magnetic moment direction
Detailed Explanation: Magnetic moment vector is directed from south pole to north pole inside the magnet.
Common trap: Students often choose formula without checking whether the point is axial, equatorial, or a general point.
JEE Main Question 79If distance from a short magnet is doubled, axial magnetic field becomes
A) 1/2
B) 1/4
C) 1/8
D) 1/16
Correct Answer: C
Difficulty: Medium-Difficult
Concept Tested: Short magnet inverse-cube law
Detailed Explanation: For a short magnet, B_axial ∝ 1/r³. Doubling r makes field 1/8.
Common trap: Students often choose formula without checking whether the point is axial, equatorial, or a general point.
Difficulty: Medium-Difficult
Concept Tested: Short magnet inverse-cube law
Detailed Explanation: For a short magnet, B_axial ∝ 1/r³. Doubling r makes field 1/8.
Common trap: Students often choose formula without checking whether the point is axial, equatorial, or a general point.
JEE Main Question 80Magnetic field lines never intersect because
A) they are imaginary
B) magnetic field has unique direction at a point
C) monopoles exist
D) field is scalar
Correct Answer: B
Difficulty: Medium-Difficult
Concept Tested: Properties of magnetic field lines
Detailed Explanation: If two field lines intersect, there would be two directions of magnetic field at the same point, which is impossible.
Common trap: Students often choose formula without checking whether the point is axial, equatorial, or a general point.
Difficulty: Medium-Difficult
Concept Tested: Properties of magnetic field lines
Detailed Explanation: If two field lines intersect, there would be two directions of magnetic field at the same point, which is impossible.
Common trap: Students often choose formula without checking whether the point is axial, equatorial, or a general point.
JEE Main Question 81For a short bar magnet, the magnetic field at an axial point and equatorial point at the same distance are in the ratio
A) 1 : 1
B) 2 : 1
C) 1 : 2
D) 4 : 1
Correct Answer: B
Difficulty: Medium-Difficult
Concept Tested: Axial and equatorial field comparison
Detailed Explanation: For a short magnet, B_axial = (μ₀/4π)(2M/r³) and B_equatorial = (μ₀/4π)(M/r³). Hence ratio is 2:1.
Common trap: Students often choose formula without checking whether the point is axial, equatorial, or a general point.
Difficulty: Medium-Difficult
Concept Tested: Axial and equatorial field comparison
Detailed Explanation: For a short magnet, B_axial = (μ₀/4π)(2M/r³) and B_equatorial = (μ₀/4π)(M/r³). Hence ratio is 2:1.
Common trap: Students often choose formula without checking whether the point is axial, equatorial, or a general point.
JEE Main Question 82A bar magnet is broken into two equal pieces perpendicular to its length. Which statement is correct?
A) Each piece has only one pole
B) Magnetic monopoles are formed
C) Each piece is a complete magnet
D) Magnetic moment becomes zero
Correct Answer: C
Difficulty: Medium-Difficult
Concept Tested: Broken magnet
Detailed Explanation: Every broken piece again has north and south poles. Magnetic monopoles are not produced by breaking a magnet.
Common trap: Students often choose formula without checking whether the point is axial, equatorial, or a general point.
Difficulty: Medium-Difficult
Concept Tested: Broken magnet
Detailed Explanation: Every broken piece again has north and south poles. Magnetic monopoles are not produced by breaking a magnet.
Common trap: Students often choose formula without checking whether the point is axial, equatorial, or a general point.
JEE Main Question 83Net magnetic flux through any closed surface is
A) μ₀ times magnetic pole inside
B) zero
C) BA always
D) infinite for a bar magnet
Correct Answer: B
Difficulty: Medium-Difficult
Concept Tested: Gauss law of magnetism
Detailed Explanation: Gauss law of magnetism gives ∮B·dA = 0 because magnetic monopoles do not exist.
Common trap: Students often choose formula without checking whether the point is axial, equatorial, or a general point.
Difficulty: Medium-Difficult
Concept Tested: Gauss law of magnetism
Detailed Explanation: Gauss law of magnetism gives ∮B·dA = 0 because magnetic monopoles do not exist.
Common trap: Students often choose formula without checking whether the point is axial, equatorial, or a general point.
JEE Main Question 84A magnetic dipole is in stable equilibrium when angle between M and B is
A) 0°
B) 90°
C) 180°
D) 270°
Correct Answer: A
Difficulty: Medium-Difficult
Concept Tested: Magnetic potential energy
Detailed Explanation: Potential energy U = -MB cosθ is minimum at θ = 0°, so equilibrium is stable.
Common trap: Students often choose formula without checking whether the point is axial, equatorial, or a general point.
Difficulty: Medium-Difficult
Concept Tested: Magnetic potential energy
Detailed Explanation: Potential energy U = -MB cosθ is minimum at θ = 0°, so equilibrium is stable.
Common trap: Students often choose formula without checking whether the point is axial, equatorial, or a general point.
JEE Main Question 85Torque on a magnetic dipole in uniform magnetic field is maximum when θ is
A) 0°
B) 45°
C) 90°
D) 180°
Correct Answer: C
Difficulty: Medium-Difficult
Concept Tested: Torque on dipole
Detailed Explanation: τ = MB sinθ is maximum when sinθ = 1, i.e. θ = 90°.
Common trap: Students often choose formula without checking whether the point is axial, equatorial, or a general point.
Difficulty: Medium-Difficult
Concept Tested: Torque on dipole
Detailed Explanation: τ = MB sinθ is maximum when sinθ = 1, i.e. θ = 90°.
Common trap: Students often choose formula without checking whether the point is axial, equatorial, or a general point.
JEE Main Question 86Direction of magnetic moment of a bar magnet is
A) N to S outside the magnet
B) S to N inside the magnet
C) Always downward
D) Opposite to magnetic field lines everywhere
Correct Answer: B
Difficulty: Medium-Difficult
Concept Tested: Magnetic moment direction
Detailed Explanation: Magnetic moment vector is directed from south pole to north pole inside the magnet.
Common trap: Students often choose formula without checking whether the point is axial, equatorial, or a general point.
Difficulty: Medium-Difficult
Concept Tested: Magnetic moment direction
Detailed Explanation: Magnetic moment vector is directed from south pole to north pole inside the magnet.
Common trap: Students often choose formula without checking whether the point is axial, equatorial, or a general point.
JEE Main Question 87If distance from a short magnet is doubled, axial magnetic field becomes
A) 1/2
B) 1/4
C) 1/8
D) 1/16
Correct Answer: C
Difficulty: Medium-Difficult
Concept Tested: Short magnet inverse-cube law
Detailed Explanation: For a short magnet, B_axial ∝ 1/r³. Doubling r makes field 1/8.
Common trap: Students often choose formula without checking whether the point is axial, equatorial, or a general point.
Difficulty: Medium-Difficult
Concept Tested: Short magnet inverse-cube law
Detailed Explanation: For a short magnet, B_axial ∝ 1/r³. Doubling r makes field 1/8.
Common trap: Students often choose formula without checking whether the point is axial, equatorial, or a general point.
JEE Main Question 88Magnetic field lines never intersect because
A) they are imaginary
B) magnetic field has unique direction at a point
C) monopoles exist
D) field is scalar
Correct Answer: B
Difficulty: Medium-Difficult
Concept Tested: Properties of magnetic field lines
Detailed Explanation: If two field lines intersect, there would be two directions of magnetic field at the same point, which is impossible.
Common trap: Students often choose formula without checking whether the point is axial, equatorial, or a general point.
Difficulty: Medium-Difficult
Concept Tested: Properties of magnetic field lines
Detailed Explanation: If two field lines intersect, there would be two directions of magnetic field at the same point, which is impossible.
Common trap: Students often choose formula without checking whether the point is axial, equatorial, or a general point.
JEE Main Question 89For a short bar magnet, the magnetic field at an axial point and equatorial point at the same distance are in the ratio
A) 1 : 1
B) 2 : 1
C) 1 : 2
D) 4 : 1
Correct Answer: B
Difficulty: Medium-Difficult
Concept Tested: Axial and equatorial field comparison
Detailed Explanation: For a short magnet, B_axial = (μ₀/4π)(2M/r³) and B_equatorial = (μ₀/4π)(M/r³). Hence ratio is 2:1.
Common trap: Students often choose formula without checking whether the point is axial, equatorial, or a general point.
Difficulty: Medium-Difficult
Concept Tested: Axial and equatorial field comparison
Detailed Explanation: For a short magnet, B_axial = (μ₀/4π)(2M/r³) and B_equatorial = (μ₀/4π)(M/r³). Hence ratio is 2:1.
Common trap: Students often choose formula without checking whether the point is axial, equatorial, or a general point.
JEE Main Question 90A bar magnet is broken into two equal pieces perpendicular to its length. Which statement is correct?
A) Each piece has only one pole
B) Magnetic monopoles are formed
C) Each piece is a complete magnet
D) Magnetic moment becomes zero
Correct Answer: C
Difficulty: Medium-Difficult
Concept Tested: Broken magnet
Detailed Explanation: Every broken piece again has north and south poles. Magnetic monopoles are not produced by breaking a magnet.
Common trap: Students often choose formula without checking whether the point is axial, equatorial, or a general point.
Difficulty: Medium-Difficult
Concept Tested: Broken magnet
Detailed Explanation: Every broken piece again has north and south poles. Magnetic monopoles are not produced by breaking a magnet.
Common trap: Students often choose formula without checking whether the point is axial, equatorial, or a general point.
JEE Main Question 91Net magnetic flux through any closed surface is
A) μ₀ times magnetic pole inside
B) zero
C) BA always
D) infinite for a bar magnet
Correct Answer: B
Difficulty: Medium-Difficult
Concept Tested: Gauss law of magnetism
Detailed Explanation: Gauss law of magnetism gives ∮B·dA = 0 because magnetic monopoles do not exist.
Common trap: Students often choose formula without checking whether the point is axial, equatorial, or a general point.
Difficulty: Medium-Difficult
Concept Tested: Gauss law of magnetism
Detailed Explanation: Gauss law of magnetism gives ∮B·dA = 0 because magnetic monopoles do not exist.
Common trap: Students often choose formula without checking whether the point is axial, equatorial, or a general point.
JEE Main Question 92A magnetic dipole is in stable equilibrium when angle between M and B is
A) 0°
B) 90°
C) 180°
D) 270°
Correct Answer: A
Difficulty: Medium-Difficult
Concept Tested: Magnetic potential energy
Detailed Explanation: Potential energy U = -MB cosθ is minimum at θ = 0°, so equilibrium is stable.
Common trap: Students often choose formula without checking whether the point is axial, equatorial, or a general point.
Difficulty: Medium-Difficult
Concept Tested: Magnetic potential energy
Detailed Explanation: Potential energy U = -MB cosθ is minimum at θ = 0°, so equilibrium is stable.
Common trap: Students often choose formula without checking whether the point is axial, equatorial, or a general point.
JEE Main Question 93Torque on a magnetic dipole in uniform magnetic field is maximum when θ is
A) 0°
B) 45°
C) 90°
D) 180°
Correct Answer: C
Difficulty: Medium-Difficult
Concept Tested: Torque on dipole
Detailed Explanation: τ = MB sinθ is maximum when sinθ = 1, i.e. θ = 90°.
Common trap: Students often choose formula without checking whether the point is axial, equatorial, or a general point.
Difficulty: Medium-Difficult
Concept Tested: Torque on dipole
Detailed Explanation: τ = MB sinθ is maximum when sinθ = 1, i.e. θ = 90°.
Common trap: Students often choose formula without checking whether the point is axial, equatorial, or a general point.
JEE Main Question 94Direction of magnetic moment of a bar magnet is
A) N to S outside the magnet
B) S to N inside the magnet
C) Always downward
D) Opposite to magnetic field lines everywhere
Correct Answer: B
Difficulty: Medium-Difficult
Concept Tested: Magnetic moment direction
Detailed Explanation: Magnetic moment vector is directed from south pole to north pole inside the magnet.
Common trap: Students often choose formula without checking whether the point is axial, equatorial, or a general point.
Difficulty: Medium-Difficult
Concept Tested: Magnetic moment direction
Detailed Explanation: Magnetic moment vector is directed from south pole to north pole inside the magnet.
Common trap: Students often choose formula without checking whether the point is axial, equatorial, or a general point.
JEE Main Question 95If distance from a short magnet is doubled, axial magnetic field becomes
A) 1/2
B) 1/4
C) 1/8
D) 1/16
Correct Answer: C
Difficulty: Medium-Difficult
Concept Tested: Short magnet inverse-cube law
Detailed Explanation: For a short magnet, B_axial ∝ 1/r³. Doubling r makes field 1/8.
Common trap: Students often choose formula without checking whether the point is axial, equatorial, or a general point.
Difficulty: Medium-Difficult
Concept Tested: Short magnet inverse-cube law
Detailed Explanation: For a short magnet, B_axial ∝ 1/r³. Doubling r makes field 1/8.
Common trap: Students often choose formula without checking whether the point is axial, equatorial, or a general point.
JEE Main Question 96Magnetic field lines never intersect because
A) they are imaginary
B) magnetic field has unique direction at a point
C) monopoles exist
D) field is scalar
Correct Answer: B
Difficulty: Medium-Difficult
Concept Tested: Properties of magnetic field lines
Detailed Explanation: If two field lines intersect, there would be two directions of magnetic field at the same point, which is impossible.
Common trap: Students often choose formula without checking whether the point is axial, equatorial, or a general point.
Difficulty: Medium-Difficult
Concept Tested: Properties of magnetic field lines
Detailed Explanation: If two field lines intersect, there would be two directions of magnetic field at the same point, which is impossible.
Common trap: Students often choose formula without checking whether the point is axial, equatorial, or a general point.
JEE Main Question 97For a short bar magnet, the magnetic field at an axial point and equatorial point at the same distance are in the ratio
A) 1 : 1
B) 2 : 1
C) 1 : 2
D) 4 : 1
Correct Answer: B
Difficulty: Medium-Difficult
Concept Tested: Axial and equatorial field comparison
Detailed Explanation: For a short magnet, B_axial = (μ₀/4π)(2M/r³) and B_equatorial = (μ₀/4π)(M/r³). Hence ratio is 2:1.
Common trap: Students often choose formula without checking whether the point is axial, equatorial, or a general point.
Difficulty: Medium-Difficult
Concept Tested: Axial and equatorial field comparison
Detailed Explanation: For a short magnet, B_axial = (μ₀/4π)(2M/r³) and B_equatorial = (μ₀/4π)(M/r³). Hence ratio is 2:1.
Common trap: Students often choose formula without checking whether the point is axial, equatorial, or a general point.
JEE Main Question 98A bar magnet is broken into two equal pieces perpendicular to its length. Which statement is correct?
A) Each piece has only one pole
B) Magnetic monopoles are formed
C) Each piece is a complete magnet
D) Magnetic moment becomes zero
Correct Answer: C
Difficulty: Medium-Difficult
Concept Tested: Broken magnet
Detailed Explanation: Every broken piece again has north and south poles. Magnetic monopoles are not produced by breaking a magnet.
Common trap: Students often choose formula without checking whether the point is axial, equatorial, or a general point.
Difficulty: Medium-Difficult
Concept Tested: Broken magnet
Detailed Explanation: Every broken piece again has north and south poles. Magnetic monopoles are not produced by breaking a magnet.
Common trap: Students often choose formula without checking whether the point is axial, equatorial, or a general point.
JEE Main Question 99Net magnetic flux through any closed surface is
A) μ₀ times magnetic pole inside
B) zero
C) BA always
D) infinite for a bar magnet
Correct Answer: B
Difficulty: Medium-Difficult
Concept Tested: Gauss law of magnetism
Detailed Explanation: Gauss law of magnetism gives ∮B·dA = 0 because magnetic monopoles do not exist.
Common trap: Students often choose formula without checking whether the point is axial, equatorial, or a general point.
Difficulty: Medium-Difficult
Concept Tested: Gauss law of magnetism
Detailed Explanation: Gauss law of magnetism gives ∮B·dA = 0 because magnetic monopoles do not exist.
Common trap: Students often choose formula without checking whether the point is axial, equatorial, or a general point.
JEE Main Question 100A magnetic dipole is in stable equilibrium when angle between M and B is
A) 0°
B) 90°
C) 180°
D) 270°
Correct Answer: A
Difficulty: Medium-Difficult
Concept Tested: Magnetic potential energy
Detailed Explanation: Potential energy U = -MB cosθ is minimum at θ = 0°, so equilibrium is stable.
Common trap: Students often choose formula without checking whether the point is axial, equatorial, or a general point.
Difficulty: Medium-Difficult
Concept Tested: Magnetic potential energy
Detailed Explanation: Potential energy U = -MB cosθ is minimum at θ = 0°, so equilibrium is stable.
Common trap: Students often choose formula without checking whether the point is axial, equatorial, or a general point.
D. JEE Advanced Single-Correct Questions
JEE Advanced Single Correct Question 1For a short bar magnet, the magnetic field at an axial point and equatorial point at the same distance are in the ratio
A) 1 : 1
B) 2 : 1
C) 1 : 2
D) 4 : 1
Correct Answer: B
Difficulty: Difficult
Concept Tested: Axial and equatorial field comparison
Detailed Explanation: For a short magnet, B_axial = (μ₀/4π)(2M/r³) and B_equatorial = (μ₀/4π)(M/r³). Hence ratio is 2:1.
Common trap: Students often choose formula without checking whether the point is axial, equatorial, or a general point.
Difficulty: Difficult
Concept Tested: Axial and equatorial field comparison
Detailed Explanation: For a short magnet, B_axial = (μ₀/4π)(2M/r³) and B_equatorial = (μ₀/4π)(M/r³). Hence ratio is 2:1.
Common trap: Students often choose formula without checking whether the point is axial, equatorial, or a general point.
JEE Advanced Single Correct Question 2A bar magnet is broken into two equal pieces perpendicular to its length. Which statement is correct?
A) Each piece has only one pole
B) Magnetic monopoles are formed
C) Each piece is a complete magnet
D) Magnetic moment becomes zero
Correct Answer: C
Difficulty: Difficult
Concept Tested: Broken magnet
Detailed Explanation: Every broken piece again has north and south poles. Magnetic monopoles are not produced by breaking a magnet.
Common trap: Students often choose formula without checking whether the point is axial, equatorial, or a general point.
Difficulty: Difficult
Concept Tested: Broken magnet
Detailed Explanation: Every broken piece again has north and south poles. Magnetic monopoles are not produced by breaking a magnet.
Common trap: Students often choose formula without checking whether the point is axial, equatorial, or a general point.
JEE Advanced Single Correct Question 3Net magnetic flux through any closed surface is
A) μ₀ times magnetic pole inside
B) zero
C) BA always
D) infinite for a bar magnet
Correct Answer: B
Difficulty: Difficult
Concept Tested: Gauss law of magnetism
Detailed Explanation: Gauss law of magnetism gives ∮B·dA = 0 because magnetic monopoles do not exist.
Common trap: Students often choose formula without checking whether the point is axial, equatorial, or a general point.
Difficulty: Difficult
Concept Tested: Gauss law of magnetism
Detailed Explanation: Gauss law of magnetism gives ∮B·dA = 0 because magnetic monopoles do not exist.
Common trap: Students often choose formula without checking whether the point is axial, equatorial, or a general point.
JEE Advanced Single Correct Question 4A magnetic dipole is in stable equilibrium when angle between M and B is
A) 0°
B) 90°
C) 180°
D) 270°
Correct Answer: A
Difficulty: Difficult
Concept Tested: Magnetic potential energy
Detailed Explanation: Potential energy U = -MB cosθ is minimum at θ = 0°, so equilibrium is stable.
Common trap: Students often choose formula without checking whether the point is axial, equatorial, or a general point.
Difficulty: Difficult
Concept Tested: Magnetic potential energy
Detailed Explanation: Potential energy U = -MB cosθ is minimum at θ = 0°, so equilibrium is stable.
Common trap: Students often choose formula without checking whether the point is axial, equatorial, or a general point.
JEE Advanced Single Correct Question 5Torque on a magnetic dipole in uniform magnetic field is maximum when θ is
A) 0°
B) 45°
C) 90°
D) 180°
Correct Answer: C
Difficulty: Difficult
Concept Tested: Torque on dipole
Detailed Explanation: τ = MB sinθ is maximum when sinθ = 1, i.e. θ = 90°.
Common trap: Students often choose formula without checking whether the point is axial, equatorial, or a general point.
Difficulty: Difficult
Concept Tested: Torque on dipole
Detailed Explanation: τ = MB sinθ is maximum when sinθ = 1, i.e. θ = 90°.
Common trap: Students often choose formula without checking whether the point is axial, equatorial, or a general point.
JEE Advanced Single Correct Question 6Direction of magnetic moment of a bar magnet is
A) N to S outside the magnet
B) S to N inside the magnet
C) Always downward
D) Opposite to magnetic field lines everywhere
Correct Answer: B
Difficulty: Difficult
Concept Tested: Magnetic moment direction
Detailed Explanation: Magnetic moment vector is directed from south pole to north pole inside the magnet.
Common trap: Students often choose formula without checking whether the point is axial, equatorial, or a general point.
Difficulty: Difficult
Concept Tested: Magnetic moment direction
Detailed Explanation: Magnetic moment vector is directed from south pole to north pole inside the magnet.
Common trap: Students often choose formula without checking whether the point is axial, equatorial, or a general point.
JEE Advanced Single Correct Question 7If distance from a short magnet is doubled, axial magnetic field becomes
A) 1/2
B) 1/4
C) 1/8
D) 1/16
Correct Answer: C
Difficulty: Difficult
Concept Tested: Short magnet inverse-cube law
Detailed Explanation: For a short magnet, B_axial ∝ 1/r³. Doubling r makes field 1/8.
Common trap: Students often choose formula without checking whether the point is axial, equatorial, or a general point.
Difficulty: Difficult
Concept Tested: Short magnet inverse-cube law
Detailed Explanation: For a short magnet, B_axial ∝ 1/r³. Doubling r makes field 1/8.
Common trap: Students often choose formula without checking whether the point is axial, equatorial, or a general point.
JEE Advanced Single Correct Question 8Magnetic field lines never intersect because
A) they are imaginary
B) magnetic field has unique direction at a point
C) monopoles exist
D) field is scalar
Correct Answer: B
Difficulty: Difficult
Concept Tested: Properties of magnetic field lines
Detailed Explanation: If two field lines intersect, there would be two directions of magnetic field at the same point, which is impossible.
Common trap: Students often choose formula without checking whether the point is axial, equatorial, or a general point.
Difficulty: Difficult
Concept Tested: Properties of magnetic field lines
Detailed Explanation: If two field lines intersect, there would be two directions of magnetic field at the same point, which is impossible.
Common trap: Students often choose formula without checking whether the point is axial, equatorial, or a general point.
JEE Advanced Single Correct Question 9For a short bar magnet, the magnetic field at an axial point and equatorial point at the same distance are in the ratio
A) 1 : 1
B) 2 : 1
C) 1 : 2
D) 4 : 1
Correct Answer: B
Difficulty: Difficult
Concept Tested: Axial and equatorial field comparison
Detailed Explanation: For a short magnet, B_axial = (μ₀/4π)(2M/r³) and B_equatorial = (μ₀/4π)(M/r³). Hence ratio is 2:1.
Common trap: Students often choose formula without checking whether the point is axial, equatorial, or a general point.
Difficulty: Difficult
Concept Tested: Axial and equatorial field comparison
Detailed Explanation: For a short magnet, B_axial = (μ₀/4π)(2M/r³) and B_equatorial = (μ₀/4π)(M/r³). Hence ratio is 2:1.
Common trap: Students often choose formula without checking whether the point is axial, equatorial, or a general point.
JEE Advanced Single Correct Question 10A bar magnet is broken into two equal pieces perpendicular to its length. Which statement is correct?
A) Each piece has only one pole
B) Magnetic monopoles are formed
C) Each piece is a complete magnet
D) Magnetic moment becomes zero
Correct Answer: C
Difficulty: Difficult
Concept Tested: Broken magnet
Detailed Explanation: Every broken piece again has north and south poles. Magnetic monopoles are not produced by breaking a magnet.
Common trap: Students often choose formula without checking whether the point is axial, equatorial, or a general point.
Difficulty: Difficult
Concept Tested: Broken magnet
Detailed Explanation: Every broken piece again has north and south poles. Magnetic monopoles are not produced by breaking a magnet.
Common trap: Students often choose formula without checking whether the point is axial, equatorial, or a general point.
JEE Advanced Single Correct Question 11Net magnetic flux through any closed surface is
A) μ₀ times magnetic pole inside
B) zero
C) BA always
D) infinite for a bar magnet
Correct Answer: B
Difficulty: Difficult
Concept Tested: Gauss law of magnetism
Detailed Explanation: Gauss law of magnetism gives ∮B·dA = 0 because magnetic monopoles do not exist.
Common trap: Students often choose formula without checking whether the point is axial, equatorial, or a general point.
Difficulty: Difficult
Concept Tested: Gauss law of magnetism
Detailed Explanation: Gauss law of magnetism gives ∮B·dA = 0 because magnetic monopoles do not exist.
Common trap: Students often choose formula without checking whether the point is axial, equatorial, or a general point.
JEE Advanced Single Correct Question 12A magnetic dipole is in stable equilibrium when angle between M and B is
A) 0°
B) 90°
C) 180°
D) 270°
Correct Answer: A
Difficulty: Difficult
Concept Tested: Magnetic potential energy
Detailed Explanation: Potential energy U = -MB cosθ is minimum at θ = 0°, so equilibrium is stable.
Common trap: Students often choose formula without checking whether the point is axial, equatorial, or a general point.
Difficulty: Difficult
Concept Tested: Magnetic potential energy
Detailed Explanation: Potential energy U = -MB cosθ is minimum at θ = 0°, so equilibrium is stable.
Common trap: Students often choose formula without checking whether the point is axial, equatorial, or a general point.
JEE Advanced Single Correct Question 13Torque on a magnetic dipole in uniform magnetic field is maximum when θ is
A) 0°
B) 45°
C) 90°
D) 180°
Correct Answer: C
Difficulty: Difficult
Concept Tested: Torque on dipole
Detailed Explanation: τ = MB sinθ is maximum when sinθ = 1, i.e. θ = 90°.
Common trap: Students often choose formula without checking whether the point is axial, equatorial, or a general point.
Difficulty: Difficult
Concept Tested: Torque on dipole
Detailed Explanation: τ = MB sinθ is maximum when sinθ = 1, i.e. θ = 90°.
Common trap: Students often choose formula without checking whether the point is axial, equatorial, or a general point.
JEE Advanced Single Correct Question 14Direction of magnetic moment of a bar magnet is
A) N to S outside the magnet
B) S to N inside the magnet
C) Always downward
D) Opposite to magnetic field lines everywhere
Correct Answer: B
Difficulty: Difficult
Concept Tested: Magnetic moment direction
Detailed Explanation: Magnetic moment vector is directed from south pole to north pole inside the magnet.
Common trap: Students often choose formula without checking whether the point is axial, equatorial, or a general point.
Difficulty: Difficult
Concept Tested: Magnetic moment direction
Detailed Explanation: Magnetic moment vector is directed from south pole to north pole inside the magnet.
Common trap: Students often choose formula without checking whether the point is axial, equatorial, or a general point.
JEE Advanced Single Correct Question 15If distance from a short magnet is doubled, axial magnetic field becomes
A) 1/2
B) 1/4
C) 1/8
D) 1/16
Correct Answer: C
Difficulty: Difficult
Concept Tested: Short magnet inverse-cube law
Detailed Explanation: For a short magnet, B_axial ∝ 1/r³. Doubling r makes field 1/8.
Common trap: Students often choose formula without checking whether the point is axial, equatorial, or a general point.
Difficulty: Difficult
Concept Tested: Short magnet inverse-cube law
Detailed Explanation: For a short magnet, B_axial ∝ 1/r³. Doubling r makes field 1/8.
Common trap: Students often choose formula without checking whether the point is axial, equatorial, or a general point.
JEE Advanced Single Correct Question 16Magnetic field lines never intersect because
A) they are imaginary
B) magnetic field has unique direction at a point
C) monopoles exist
D) field is scalar
Correct Answer: B
Difficulty: Difficult
Concept Tested: Properties of magnetic field lines
Detailed Explanation: If two field lines intersect, there would be two directions of magnetic field at the same point, which is impossible.
Common trap: Students often choose formula without checking whether the point is axial, equatorial, or a general point.
Difficulty: Difficult
Concept Tested: Properties of magnetic field lines
Detailed Explanation: If two field lines intersect, there would be two directions of magnetic field at the same point, which is impossible.
Common trap: Students often choose formula without checking whether the point is axial, equatorial, or a general point.
JEE Advanced Single Correct Question 17For a short bar magnet, the magnetic field at an axial point and equatorial point at the same distance are in the ratio
A) 1 : 1
B) 2 : 1
C) 1 : 2
D) 4 : 1
Correct Answer: B
Difficulty: Difficult
Concept Tested: Axial and equatorial field comparison
Detailed Explanation: For a short magnet, B_axial = (μ₀/4π)(2M/r³) and B_equatorial = (μ₀/4π)(M/r³). Hence ratio is 2:1.
Common trap: Students often choose formula without checking whether the point is axial, equatorial, or a general point.
Difficulty: Difficult
Concept Tested: Axial and equatorial field comparison
Detailed Explanation: For a short magnet, B_axial = (μ₀/4π)(2M/r³) and B_equatorial = (μ₀/4π)(M/r³). Hence ratio is 2:1.
Common trap: Students often choose formula without checking whether the point is axial, equatorial, or a general point.
JEE Advanced Single Correct Question 18A bar magnet is broken into two equal pieces perpendicular to its length. Which statement is correct?
A) Each piece has only one pole
B) Magnetic monopoles are formed
C) Each piece is a complete magnet
D) Magnetic moment becomes zero
Correct Answer: C
Difficulty: Difficult
Concept Tested: Broken magnet
Detailed Explanation: Every broken piece again has north and south poles. Magnetic monopoles are not produced by breaking a magnet.
Common trap: Students often choose formula without checking whether the point is axial, equatorial, or a general point.
Difficulty: Difficult
Concept Tested: Broken magnet
Detailed Explanation: Every broken piece again has north and south poles. Magnetic monopoles are not produced by breaking a magnet.
Common trap: Students often choose formula without checking whether the point is axial, equatorial, or a general point.
JEE Advanced Single Correct Question 19Net magnetic flux through any closed surface is
A) μ₀ times magnetic pole inside
B) zero
C) BA always
D) infinite for a bar magnet
Correct Answer: B
Difficulty: Difficult
Concept Tested: Gauss law of magnetism
Detailed Explanation: Gauss law of magnetism gives ∮B·dA = 0 because magnetic monopoles do not exist.
Common trap: Students often choose formula without checking whether the point is axial, equatorial, or a general point.
Difficulty: Difficult
Concept Tested: Gauss law of magnetism
Detailed Explanation: Gauss law of magnetism gives ∮B·dA = 0 because magnetic monopoles do not exist.
Common trap: Students often choose formula without checking whether the point is axial, equatorial, or a general point.
JEE Advanced Single Correct Question 20A magnetic dipole is in stable equilibrium when angle between M and B is
A) 0°
B) 90°
C) 180°
D) 270°
Correct Answer: A
Difficulty: Difficult
Concept Tested: Magnetic potential energy
Detailed Explanation: Potential energy U = -MB cosθ is minimum at θ = 0°, so equilibrium is stable.
Common trap: Students often choose formula without checking whether the point is axial, equatorial, or a general point.
Difficulty: Difficult
Concept Tested: Magnetic potential energy
Detailed Explanation: Potential energy U = -MB cosθ is minimum at θ = 0°, so equilibrium is stable.
Common trap: Students often choose formula without checking whether the point is axial, equatorial, or a general point.
JEE Advanced Single Correct Question 21Torque on a magnetic dipole in uniform magnetic field is maximum when θ is
A) 0°
B) 45°
C) 90°
D) 180°
Correct Answer: C
Difficulty: Difficult
Concept Tested: Torque on dipole
Detailed Explanation: τ = MB sinθ is maximum when sinθ = 1, i.e. θ = 90°.
Common trap: Students often choose formula without checking whether the point is axial, equatorial, or a general point.
Difficulty: Difficult
Concept Tested: Torque on dipole
Detailed Explanation: τ = MB sinθ is maximum when sinθ = 1, i.e. θ = 90°.
Common trap: Students often choose formula without checking whether the point is axial, equatorial, or a general point.
JEE Advanced Single Correct Question 22Direction of magnetic moment of a bar magnet is
A) N to S outside the magnet
B) S to N inside the magnet
C) Always downward
D) Opposite to magnetic field lines everywhere
Correct Answer: B
Difficulty: Difficult
Concept Tested: Magnetic moment direction
Detailed Explanation: Magnetic moment vector is directed from south pole to north pole inside the magnet.
Common trap: Students often choose formula without checking whether the point is axial, equatorial, or a general point.
Difficulty: Difficult
Concept Tested: Magnetic moment direction
Detailed Explanation: Magnetic moment vector is directed from south pole to north pole inside the magnet.
Common trap: Students often choose formula without checking whether the point is axial, equatorial, or a general point.
JEE Advanced Single Correct Question 23If distance from a short magnet is doubled, axial magnetic field becomes
A) 1/2
B) 1/4
C) 1/8
D) 1/16
Correct Answer: C
Difficulty: Difficult
Concept Tested: Short magnet inverse-cube law
Detailed Explanation: For a short magnet, B_axial ∝ 1/r³. Doubling r makes field 1/8.
Common trap: Students often choose formula without checking whether the point is axial, equatorial, or a general point.
Difficulty: Difficult
Concept Tested: Short magnet inverse-cube law
Detailed Explanation: For a short magnet, B_axial ∝ 1/r³. Doubling r makes field 1/8.
Common trap: Students often choose formula without checking whether the point is axial, equatorial, or a general point.
JEE Advanced Single Correct Question 24Magnetic field lines never intersect because
A) they are imaginary
B) magnetic field has unique direction at a point
C) monopoles exist
D) field is scalar
Correct Answer: B
Difficulty: Difficult
Concept Tested: Properties of magnetic field lines
Detailed Explanation: If two field lines intersect, there would be two directions of magnetic field at the same point, which is impossible.
Common trap: Students often choose formula without checking whether the point is axial, equatorial, or a general point.
Difficulty: Difficult
Concept Tested: Properties of magnetic field lines
Detailed Explanation: If two field lines intersect, there would be two directions of magnetic field at the same point, which is impossible.
Common trap: Students often choose formula without checking whether the point is axial, equatorial, or a general point.
JEE Advanced Single Correct Question 25For a short bar magnet, the magnetic field at an axial point and equatorial point at the same distance are in the ratio
A) 1 : 1
B) 2 : 1
C) 1 : 2
D) 4 : 1
Correct Answer: B
Difficulty: Difficult
Concept Tested: Axial and equatorial field comparison
Detailed Explanation: For a short magnet, B_axial = (μ₀/4π)(2M/r³) and B_equatorial = (μ₀/4π)(M/r³). Hence ratio is 2:1.
Common trap: Students often choose formula without checking whether the point is axial, equatorial, or a general point.
Difficulty: Difficult
Concept Tested: Axial and equatorial field comparison
Detailed Explanation: For a short magnet, B_axial = (μ₀/4π)(2M/r³) and B_equatorial = (μ₀/4π)(M/r³). Hence ratio is 2:1.
Common trap: Students often choose formula without checking whether the point is axial, equatorial, or a general point.
JEE Advanced Single Correct Question 26A bar magnet is broken into two equal pieces perpendicular to its length. Which statement is correct?
A) Each piece has only one pole
B) Magnetic monopoles are formed
C) Each piece is a complete magnet
D) Magnetic moment becomes zero
Correct Answer: C
Difficulty: Difficult
Concept Tested: Broken magnet
Detailed Explanation: Every broken piece again has north and south poles. Magnetic monopoles are not produced by breaking a magnet.
Common trap: Students often choose formula without checking whether the point is axial, equatorial, or a general point.
Difficulty: Difficult
Concept Tested: Broken magnet
Detailed Explanation: Every broken piece again has north and south poles. Magnetic monopoles are not produced by breaking a magnet.
Common trap: Students often choose formula without checking whether the point is axial, equatorial, or a general point.
JEE Advanced Single Correct Question 27Net magnetic flux through any closed surface is
A) μ₀ times magnetic pole inside
B) zero
C) BA always
D) infinite for a bar magnet
Correct Answer: B
Difficulty: Difficult
Concept Tested: Gauss law of magnetism
Detailed Explanation: Gauss law of magnetism gives ∮B·dA = 0 because magnetic monopoles do not exist.
Common trap: Students often choose formula without checking whether the point is axial, equatorial, or a general point.
Difficulty: Difficult
Concept Tested: Gauss law of magnetism
Detailed Explanation: Gauss law of magnetism gives ∮B·dA = 0 because magnetic monopoles do not exist.
Common trap: Students often choose formula without checking whether the point is axial, equatorial, or a general point.
JEE Advanced Single Correct Question 28A magnetic dipole is in stable equilibrium when angle between M and B is
A) 0°
B) 90°
C) 180°
D) 270°
Correct Answer: A
Difficulty: Difficult
Concept Tested: Magnetic potential energy
Detailed Explanation: Potential energy U = -MB cosθ is minimum at θ = 0°, so equilibrium is stable.
Common trap: Students often choose formula without checking whether the point is axial, equatorial, or a general point.
Difficulty: Difficult
Concept Tested: Magnetic potential energy
Detailed Explanation: Potential energy U = -MB cosθ is minimum at θ = 0°, so equilibrium is stable.
Common trap: Students often choose formula without checking whether the point is axial, equatorial, or a general point.
JEE Advanced Single Correct Question 29Torque on a magnetic dipole in uniform magnetic field is maximum when θ is
A) 0°
B) 45°
C) 90°
D) 180°
Correct Answer: C
Difficulty: Difficult
Concept Tested: Torque on dipole
Detailed Explanation: τ = MB sinθ is maximum when sinθ = 1, i.e. θ = 90°.
Common trap: Students often choose formula without checking whether the point is axial, equatorial, or a general point.
Difficulty: Difficult
Concept Tested: Torque on dipole
Detailed Explanation: τ = MB sinθ is maximum when sinθ = 1, i.e. θ = 90°.
Common trap: Students often choose formula without checking whether the point is axial, equatorial, or a general point.
JEE Advanced Single Correct Question 30Direction of magnetic moment of a bar magnet is
A) N to S outside the magnet
B) S to N inside the magnet
C) Always downward
D) Opposite to magnetic field lines everywhere
Correct Answer: B
Difficulty: Difficult
Concept Tested: Magnetic moment direction
Detailed Explanation: Magnetic moment vector is directed from south pole to north pole inside the magnet.
Common trap: Students often choose formula without checking whether the point is axial, equatorial, or a general point.
Difficulty: Difficult
Concept Tested: Magnetic moment direction
Detailed Explanation: Magnetic moment vector is directed from south pole to north pole inside the magnet.
Common trap: Students often choose formula without checking whether the point is axial, equatorial, or a general point.
JEE Advanced Single Correct Question 31If distance from a short magnet is doubled, axial magnetic field becomes
A) 1/2
B) 1/4
C) 1/8
D) 1/16
Correct Answer: C
Difficulty: Difficult
Concept Tested: Short magnet inverse-cube law
Detailed Explanation: For a short magnet, B_axial ∝ 1/r³. Doubling r makes field 1/8.
Common trap: Students often choose formula without checking whether the point is axial, equatorial, or a general point.
Difficulty: Difficult
Concept Tested: Short magnet inverse-cube law
Detailed Explanation: For a short magnet, B_axial ∝ 1/r³. Doubling r makes field 1/8.
Common trap: Students often choose formula without checking whether the point is axial, equatorial, or a general point.
JEE Advanced Single Correct Question 32Magnetic field lines never intersect because
A) they are imaginary
B) magnetic field has unique direction at a point
C) monopoles exist
D) field is scalar
Correct Answer: B
Difficulty: Difficult
Concept Tested: Properties of magnetic field lines
Detailed Explanation: If two field lines intersect, there would be two directions of magnetic field at the same point, which is impossible.
Common trap: Students often choose formula without checking whether the point is axial, equatorial, or a general point.
Difficulty: Difficult
Concept Tested: Properties of magnetic field lines
Detailed Explanation: If two field lines intersect, there would be two directions of magnetic field at the same point, which is impossible.
Common trap: Students often choose formula without checking whether the point is axial, equatorial, or a general point.
JEE Advanced Single Correct Question 33For a short bar magnet, the magnetic field at an axial point and equatorial point at the same distance are in the ratio
A) 1 : 1
B) 2 : 1
C) 1 : 2
D) 4 : 1
Correct Answer: B
Difficulty: Difficult
Concept Tested: Axial and equatorial field comparison
Detailed Explanation: For a short magnet, B_axial = (μ₀/4π)(2M/r³) and B_equatorial = (μ₀/4π)(M/r³). Hence ratio is 2:1.
Common trap: Students often choose formula without checking whether the point is axial, equatorial, or a general point.
Difficulty: Difficult
Concept Tested: Axial and equatorial field comparison
Detailed Explanation: For a short magnet, B_axial = (μ₀/4π)(2M/r³) and B_equatorial = (μ₀/4π)(M/r³). Hence ratio is 2:1.
Common trap: Students often choose formula without checking whether the point is axial, equatorial, or a general point.
JEE Advanced Single Correct Question 34A bar magnet is broken into two equal pieces perpendicular to its length. Which statement is correct?
A) Each piece has only one pole
B) Magnetic monopoles are formed
C) Each piece is a complete magnet
D) Magnetic moment becomes zero
Correct Answer: C
Difficulty: Difficult
Concept Tested: Broken magnet
Detailed Explanation: Every broken piece again has north and south poles. Magnetic monopoles are not produced by breaking a magnet.
Common trap: Students often choose formula without checking whether the point is axial, equatorial, or a general point.
Difficulty: Difficult
Concept Tested: Broken magnet
Detailed Explanation: Every broken piece again has north and south poles. Magnetic monopoles are not produced by breaking a magnet.
Common trap: Students often choose formula without checking whether the point is axial, equatorial, or a general point.
JEE Advanced Single Correct Question 35Net magnetic flux through any closed surface is
A) μ₀ times magnetic pole inside
B) zero
C) BA always
D) infinite for a bar magnet
Correct Answer: B
Difficulty: Difficult
Concept Tested: Gauss law of magnetism
Detailed Explanation: Gauss law of magnetism gives ∮B·dA = 0 because magnetic monopoles do not exist.
Common trap: Students often choose formula without checking whether the point is axial, equatorial, or a general point.
Difficulty: Difficult
Concept Tested: Gauss law of magnetism
Detailed Explanation: Gauss law of magnetism gives ∮B·dA = 0 because magnetic monopoles do not exist.
Common trap: Students often choose formula without checking whether the point is axial, equatorial, or a general point.
JEE Advanced Single Correct Question 36A magnetic dipole is in stable equilibrium when angle between M and B is
A) 0°
B) 90°
C) 180°
D) 270°
Correct Answer: A
Difficulty: Difficult
Concept Tested: Magnetic potential energy
Detailed Explanation: Potential energy U = -MB cosθ is minimum at θ = 0°, so equilibrium is stable.
Common trap: Students often choose formula without checking whether the point is axial, equatorial, or a general point.
Difficulty: Difficult
Concept Tested: Magnetic potential energy
Detailed Explanation: Potential energy U = -MB cosθ is minimum at θ = 0°, so equilibrium is stable.
Common trap: Students often choose formula without checking whether the point is axial, equatorial, or a general point.
JEE Advanced Single Correct Question 37Torque on a magnetic dipole in uniform magnetic field is maximum when θ is
A) 0°
B) 45°
C) 90°
D) 180°
Correct Answer: C
Difficulty: Difficult
Concept Tested: Torque on dipole
Detailed Explanation: τ = MB sinθ is maximum when sinθ = 1, i.e. θ = 90°.
Common trap: Students often choose formula without checking whether the point is axial, equatorial, or a general point.
Difficulty: Difficult
Concept Tested: Torque on dipole
Detailed Explanation: τ = MB sinθ is maximum when sinθ = 1, i.e. θ = 90°.
Common trap: Students often choose formula without checking whether the point is axial, equatorial, or a general point.
JEE Advanced Single Correct Question 38Direction of magnetic moment of a bar magnet is
A) N to S outside the magnet
B) S to N inside the magnet
C) Always downward
D) Opposite to magnetic field lines everywhere
Correct Answer: B
Difficulty: Difficult
Concept Tested: Magnetic moment direction
Detailed Explanation: Magnetic moment vector is directed from south pole to north pole inside the magnet.
Common trap: Students often choose formula without checking whether the point is axial, equatorial, or a general point.
Difficulty: Difficult
Concept Tested: Magnetic moment direction
Detailed Explanation: Magnetic moment vector is directed from south pole to north pole inside the magnet.
Common trap: Students often choose formula without checking whether the point is axial, equatorial, or a general point.
JEE Advanced Single Correct Question 39If distance from a short magnet is doubled, axial magnetic field becomes
A) 1/2
B) 1/4
C) 1/8
D) 1/16
Correct Answer: C
Difficulty: Difficult
Concept Tested: Short magnet inverse-cube law
Detailed Explanation: For a short magnet, B_axial ∝ 1/r³. Doubling r makes field 1/8.
Common trap: Students often choose formula without checking whether the point is axial, equatorial, or a general point.
Difficulty: Difficult
Concept Tested: Short magnet inverse-cube law
Detailed Explanation: For a short magnet, B_axial ∝ 1/r³. Doubling r makes field 1/8.
Common trap: Students often choose formula without checking whether the point is axial, equatorial, or a general point.
JEE Advanced Single Correct Question 40Magnetic field lines never intersect because
A) they are imaginary
B) magnetic field has unique direction at a point
C) monopoles exist
D) field is scalar
Correct Answer: B
Difficulty: Difficult
Concept Tested: Properties of magnetic field lines
Detailed Explanation: If two field lines intersect, there would be two directions of magnetic field at the same point, which is impossible.
Common trap: Students often choose formula without checking whether the point is axial, equatorial, or a general point.
Difficulty: Difficult
Concept Tested: Properties of magnetic field lines
Detailed Explanation: If two field lines intersect, there would be two directions of magnetic field at the same point, which is impossible.
Common trap: Students often choose formula without checking whether the point is axial, equatorial, or a general point.
D. JEE Advanced Multiple-Correct Questions
JEE Advanced Multiple Correct Question 1For a short bar magnet, the magnetic field at an axial point and equatorial point at the same distance are in the ratio
A) 1 : 1
B) 2 : 1
C) 1 : 2
D) 4 : 1
Correct Answer: B
Difficulty: Difficult
Concept Tested: Axial and equatorial field comparison
Detailed Explanation: For a short magnet, B_axial = (μ₀/4π)(2M/r³) and B_equatorial = (μ₀/4π)(M/r³). Hence ratio is 2:1.
Common trap: Students often choose formula without checking whether the point is axial, equatorial, or a general point.
Difficulty: Difficult
Concept Tested: Axial and equatorial field comparison
Detailed Explanation: For a short magnet, B_axial = (μ₀/4π)(2M/r³) and B_equatorial = (μ₀/4π)(M/r³). Hence ratio is 2:1.
Common trap: Students often choose formula without checking whether the point is axial, equatorial, or a general point.
JEE Advanced Multiple Correct Question 2A bar magnet is broken into two equal pieces perpendicular to its length. Which statement is correct?
A) Each piece has only one pole
B) Magnetic monopoles are formed
C) Each piece is a complete magnet
D) Magnetic moment becomes zero
Correct Answer: C
Difficulty: Difficult
Concept Tested: Broken magnet
Detailed Explanation: Every broken piece again has north and south poles. Magnetic monopoles are not produced by breaking a magnet.
Common trap: Students often choose formula without checking whether the point is axial, equatorial, or a general point.
Difficulty: Difficult
Concept Tested: Broken magnet
Detailed Explanation: Every broken piece again has north and south poles. Magnetic monopoles are not produced by breaking a magnet.
Common trap: Students often choose formula without checking whether the point is axial, equatorial, or a general point.
JEE Advanced Multiple Correct Question 3Net magnetic flux through any closed surface is
A) μ₀ times magnetic pole inside
B) zero
C) BA always
D) infinite for a bar magnet
Correct Answer: B
Difficulty: Difficult
Concept Tested: Gauss law of magnetism
Detailed Explanation: Gauss law of magnetism gives ∮B·dA = 0 because magnetic monopoles do not exist.
Common trap: Students often choose formula without checking whether the point is axial, equatorial, or a general point.
Difficulty: Difficult
Concept Tested: Gauss law of magnetism
Detailed Explanation: Gauss law of magnetism gives ∮B·dA = 0 because magnetic monopoles do not exist.
Common trap: Students often choose formula without checking whether the point is axial, equatorial, or a general point.
JEE Advanced Multiple Correct Question 4A magnetic dipole is in stable equilibrium when angle between M and B is
A) 0°
B) 90°
C) 180°
D) 270°
Correct Answer: A
Difficulty: Difficult
Concept Tested: Magnetic potential energy
Detailed Explanation: Potential energy U = -MB cosθ is minimum at θ = 0°, so equilibrium is stable.
Common trap: Students often choose formula without checking whether the point is axial, equatorial, or a general point.
Difficulty: Difficult
Concept Tested: Magnetic potential energy
Detailed Explanation: Potential energy U = -MB cosθ is minimum at θ = 0°, so equilibrium is stable.
Common trap: Students often choose formula without checking whether the point is axial, equatorial, or a general point.
JEE Advanced Multiple Correct Question 5Torque on a magnetic dipole in uniform magnetic field is maximum when θ is
A) 0°
B) 45°
C) 90°
D) 180°
Correct Answer: C
Difficulty: Difficult
Concept Tested: Torque on dipole
Detailed Explanation: τ = MB sinθ is maximum when sinθ = 1, i.e. θ = 90°.
Common trap: Students often choose formula without checking whether the point is axial, equatorial, or a general point.
Difficulty: Difficult
Concept Tested: Torque on dipole
Detailed Explanation: τ = MB sinθ is maximum when sinθ = 1, i.e. θ = 90°.
Common trap: Students often choose formula without checking whether the point is axial, equatorial, or a general point.
JEE Advanced Multiple Correct Question 6Direction of magnetic moment of a bar magnet is
A) N to S outside the magnet
B) S to N inside the magnet
C) Always downward
D) Opposite to magnetic field lines everywhere
Correct Answer: B
Difficulty: Difficult
Concept Tested: Magnetic moment direction
Detailed Explanation: Magnetic moment vector is directed from south pole to north pole inside the magnet.
Common trap: Students often choose formula without checking whether the point is axial, equatorial, or a general point.
Difficulty: Difficult
Concept Tested: Magnetic moment direction
Detailed Explanation: Magnetic moment vector is directed from south pole to north pole inside the magnet.
Common trap: Students often choose formula without checking whether the point is axial, equatorial, or a general point.
JEE Advanced Multiple Correct Question 7If distance from a short magnet is doubled, axial magnetic field becomes
A) 1/2
B) 1/4
C) 1/8
D) 1/16
Correct Answer: C
Difficulty: Difficult
Concept Tested: Short magnet inverse-cube law
Detailed Explanation: For a short magnet, B_axial ∝ 1/r³. Doubling r makes field 1/8.
Common trap: Students often choose formula without checking whether the point is axial, equatorial, or a general point.
Difficulty: Difficult
Concept Tested: Short magnet inverse-cube law
Detailed Explanation: For a short magnet, B_axial ∝ 1/r³. Doubling r makes field 1/8.
Common trap: Students often choose formula without checking whether the point is axial, equatorial, or a general point.
JEE Advanced Multiple Correct Question 8Magnetic field lines never intersect because
A) they are imaginary
B) magnetic field has unique direction at a point
C) monopoles exist
D) field is scalar
Correct Answer: B
Difficulty: Difficult
Concept Tested: Properties of magnetic field lines
Detailed Explanation: If two field lines intersect, there would be two directions of magnetic field at the same point, which is impossible.
Common trap: Students often choose formula without checking whether the point is axial, equatorial, or a general point.
Difficulty: Difficult
Concept Tested: Properties of magnetic field lines
Detailed Explanation: If two field lines intersect, there would be two directions of magnetic field at the same point, which is impossible.
Common trap: Students often choose formula without checking whether the point is axial, equatorial, or a general point.
JEE Advanced Multiple Correct Question 9For a short bar magnet, the magnetic field at an axial point and equatorial point at the same distance are in the ratio
A) 1 : 1
B) 2 : 1
C) 1 : 2
D) 4 : 1
Correct Answer: B
Difficulty: Difficult
Concept Tested: Axial and equatorial field comparison
Detailed Explanation: For a short magnet, B_axial = (μ₀/4π)(2M/r³) and B_equatorial = (μ₀/4π)(M/r³). Hence ratio is 2:1.
Common trap: Students often choose formula without checking whether the point is axial, equatorial, or a general point.
Difficulty: Difficult
Concept Tested: Axial and equatorial field comparison
Detailed Explanation: For a short magnet, B_axial = (μ₀/4π)(2M/r³) and B_equatorial = (μ₀/4π)(M/r³). Hence ratio is 2:1.
Common trap: Students often choose formula without checking whether the point is axial, equatorial, or a general point.
JEE Advanced Multiple Correct Question 10A bar magnet is broken into two equal pieces perpendicular to its length. Which statement is correct?
A) Each piece has only one pole
B) Magnetic monopoles are formed
C) Each piece is a complete magnet
D) Magnetic moment becomes zero
Correct Answer: C
Difficulty: Difficult
Concept Tested: Broken magnet
Detailed Explanation: Every broken piece again has north and south poles. Magnetic monopoles are not produced by breaking a magnet.
Common trap: Students often choose formula without checking whether the point is axial, equatorial, or a general point.
Difficulty: Difficult
Concept Tested: Broken magnet
Detailed Explanation: Every broken piece again has north and south poles. Magnetic monopoles are not produced by breaking a magnet.
Common trap: Students often choose formula without checking whether the point is axial, equatorial, or a general point.
JEE Advanced Multiple Correct Question 11Net magnetic flux through any closed surface is
A) μ₀ times magnetic pole inside
B) zero
C) BA always
D) infinite for a bar magnet
Correct Answer: B
Difficulty: Difficult
Concept Tested: Gauss law of magnetism
Detailed Explanation: Gauss law of magnetism gives ∮B·dA = 0 because magnetic monopoles do not exist.
Common trap: Students often choose formula without checking whether the point is axial, equatorial, or a general point.
Difficulty: Difficult
Concept Tested: Gauss law of magnetism
Detailed Explanation: Gauss law of magnetism gives ∮B·dA = 0 because magnetic monopoles do not exist.
Common trap: Students often choose formula without checking whether the point is axial, equatorial, or a general point.
JEE Advanced Multiple Correct Question 12A magnetic dipole is in stable equilibrium when angle between M and B is
A) 0°
B) 90°
C) 180°
D) 270°
Correct Answer: A
Difficulty: Difficult
Concept Tested: Magnetic potential energy
Detailed Explanation: Potential energy U = -MB cosθ is minimum at θ = 0°, so equilibrium is stable.
Common trap: Students often choose formula without checking whether the point is axial, equatorial, or a general point.
Difficulty: Difficult
Concept Tested: Magnetic potential energy
Detailed Explanation: Potential energy U = -MB cosθ is minimum at θ = 0°, so equilibrium is stable.
Common trap: Students often choose formula without checking whether the point is axial, equatorial, or a general point.
JEE Advanced Multiple Correct Question 13Torque on a magnetic dipole in uniform magnetic field is maximum when θ is
A) 0°
B) 45°
C) 90°
D) 180°
Correct Answer: C
Difficulty: Difficult
Concept Tested: Torque on dipole
Detailed Explanation: τ = MB sinθ is maximum when sinθ = 1, i.e. θ = 90°.
Common trap: Students often choose formula without checking whether the point is axial, equatorial, or a general point.
Difficulty: Difficult
Concept Tested: Torque on dipole
Detailed Explanation: τ = MB sinθ is maximum when sinθ = 1, i.e. θ = 90°.
Common trap: Students often choose formula without checking whether the point is axial, equatorial, or a general point.
JEE Advanced Multiple Correct Question 14Direction of magnetic moment of a bar magnet is
A) N to S outside the magnet
B) S to N inside the magnet
C) Always downward
D) Opposite to magnetic field lines everywhere
Correct Answer: B
Difficulty: Difficult
Concept Tested: Magnetic moment direction
Detailed Explanation: Magnetic moment vector is directed from south pole to north pole inside the magnet.
Common trap: Students often choose formula without checking whether the point is axial, equatorial, or a general point.
Difficulty: Difficult
Concept Tested: Magnetic moment direction
Detailed Explanation: Magnetic moment vector is directed from south pole to north pole inside the magnet.
Common trap: Students often choose formula without checking whether the point is axial, equatorial, or a general point.
JEE Advanced Multiple Correct Question 15If distance from a short magnet is doubled, axial magnetic field becomes
A) 1/2
B) 1/4
C) 1/8
D) 1/16
Correct Answer: C
Difficulty: Difficult
Concept Tested: Short magnet inverse-cube law
Detailed Explanation: For a short magnet, B_axial ∝ 1/r³. Doubling r makes field 1/8.
Common trap: Students often choose formula without checking whether the point is axial, equatorial, or a general point.
Difficulty: Difficult
Concept Tested: Short magnet inverse-cube law
Detailed Explanation: For a short magnet, B_axial ∝ 1/r³. Doubling r makes field 1/8.
Common trap: Students often choose formula without checking whether the point is axial, equatorial, or a general point.
JEE Advanced Multiple Correct Question 16Magnetic field lines never intersect because
A) they are imaginary
B) magnetic field has unique direction at a point
C) monopoles exist
D) field is scalar
Correct Answer: B
Difficulty: Difficult
Concept Tested: Properties of magnetic field lines
Detailed Explanation: If two field lines intersect, there would be two directions of magnetic field at the same point, which is impossible.
Common trap: Students often choose formula without checking whether the point is axial, equatorial, or a general point.
Difficulty: Difficult
Concept Tested: Properties of magnetic field lines
Detailed Explanation: If two field lines intersect, there would be two directions of magnetic field at the same point, which is impossible.
Common trap: Students often choose formula without checking whether the point is axial, equatorial, or a general point.
JEE Advanced Multiple Correct Question 17For a short bar magnet, the magnetic field at an axial point and equatorial point at the same distance are in the ratio
A) 1 : 1
B) 2 : 1
C) 1 : 2
D) 4 : 1
Correct Answer: B
Difficulty: Difficult
Concept Tested: Axial and equatorial field comparison
Detailed Explanation: For a short magnet, B_axial = (μ₀/4π)(2M/r³) and B_equatorial = (μ₀/4π)(M/r³). Hence ratio is 2:1.
Common trap: Students often choose formula without checking whether the point is axial, equatorial, or a general point.
Difficulty: Difficult
Concept Tested: Axial and equatorial field comparison
Detailed Explanation: For a short magnet, B_axial = (μ₀/4π)(2M/r³) and B_equatorial = (μ₀/4π)(M/r³). Hence ratio is 2:1.
Common trap: Students often choose formula without checking whether the point is axial, equatorial, or a general point.
JEE Advanced Multiple Correct Question 18A bar magnet is broken into two equal pieces perpendicular to its length. Which statement is correct?
A) Each piece has only one pole
B) Magnetic monopoles are formed
C) Each piece is a complete magnet
D) Magnetic moment becomes zero
Correct Answer: C
Difficulty: Difficult
Concept Tested: Broken magnet
Detailed Explanation: Every broken piece again has north and south poles. Magnetic monopoles are not produced by breaking a magnet.
Common trap: Students often choose formula without checking whether the point is axial, equatorial, or a general point.
Difficulty: Difficult
Concept Tested: Broken magnet
Detailed Explanation: Every broken piece again has north and south poles. Magnetic monopoles are not produced by breaking a magnet.
Common trap: Students often choose formula without checking whether the point is axial, equatorial, or a general point.
JEE Advanced Multiple Correct Question 19Net magnetic flux through any closed surface is
A) μ₀ times magnetic pole inside
B) zero
C) BA always
D) infinite for a bar magnet
Correct Answer: B
Difficulty: Difficult
Concept Tested: Gauss law of magnetism
Detailed Explanation: Gauss law of magnetism gives ∮B·dA = 0 because magnetic monopoles do not exist.
Common trap: Students often choose formula without checking whether the point is axial, equatorial, or a general point.
Difficulty: Difficult
Concept Tested: Gauss law of magnetism
Detailed Explanation: Gauss law of magnetism gives ∮B·dA = 0 because magnetic monopoles do not exist.
Common trap: Students often choose formula without checking whether the point is axial, equatorial, or a general point.
JEE Advanced Multiple Correct Question 20A magnetic dipole is in stable equilibrium when angle between M and B is
A) 0°
B) 90°
C) 180°
D) 270°
Correct Answer: A
Difficulty: Difficult
Concept Tested: Magnetic potential energy
Detailed Explanation: Potential energy U = -MB cosθ is minimum at θ = 0°, so equilibrium is stable.
Common trap: Students often choose formula without checking whether the point is axial, equatorial, or a general point.
Difficulty: Difficult
Concept Tested: Magnetic potential energy
Detailed Explanation: Potential energy U = -MB cosθ is minimum at θ = 0°, so equilibrium is stable.
Common trap: Students often choose formula without checking whether the point is axial, equatorial, or a general point.
JEE Advanced Multiple Correct Question 21Torque on a magnetic dipole in uniform magnetic field is maximum when θ is
A) 0°
B) 45°
C) 90°
D) 180°
Correct Answer: C
Difficulty: Difficult
Concept Tested: Torque on dipole
Detailed Explanation: τ = MB sinθ is maximum when sinθ = 1, i.e. θ = 90°.
Common trap: Students often choose formula without checking whether the point is axial, equatorial, or a general point.
Difficulty: Difficult
Concept Tested: Torque on dipole
Detailed Explanation: τ = MB sinθ is maximum when sinθ = 1, i.e. θ = 90°.
Common trap: Students often choose formula without checking whether the point is axial, equatorial, or a general point.
JEE Advanced Multiple Correct Question 22Direction of magnetic moment of a bar magnet is
A) N to S outside the magnet
B) S to N inside the magnet
C) Always downward
D) Opposite to magnetic field lines everywhere
Correct Answer: B
Difficulty: Difficult
Concept Tested: Magnetic moment direction
Detailed Explanation: Magnetic moment vector is directed from south pole to north pole inside the magnet.
Common trap: Students often choose formula without checking whether the point is axial, equatorial, or a general point.
Difficulty: Difficult
Concept Tested: Magnetic moment direction
Detailed Explanation: Magnetic moment vector is directed from south pole to north pole inside the magnet.
Common trap: Students often choose formula without checking whether the point is axial, equatorial, or a general point.
JEE Advanced Multiple Correct Question 23If distance from a short magnet is doubled, axial magnetic field becomes
A) 1/2
B) 1/4
C) 1/8
D) 1/16
Correct Answer: C
Difficulty: Difficult
Concept Tested: Short magnet inverse-cube law
Detailed Explanation: For a short magnet, B_axial ∝ 1/r³. Doubling r makes field 1/8.
Common trap: Students often choose formula without checking whether the point is axial, equatorial, or a general point.
Difficulty: Difficult
Concept Tested: Short magnet inverse-cube law
Detailed Explanation: For a short magnet, B_axial ∝ 1/r³. Doubling r makes field 1/8.
Common trap: Students often choose formula without checking whether the point is axial, equatorial, or a general point.
JEE Advanced Multiple Correct Question 24Magnetic field lines never intersect because
A) they are imaginary
B) magnetic field has unique direction at a point
C) monopoles exist
D) field is scalar
Correct Answer: B
Difficulty: Difficult
Concept Tested: Properties of magnetic field lines
Detailed Explanation: If two field lines intersect, there would be two directions of magnetic field at the same point, which is impossible.
Common trap: Students often choose formula without checking whether the point is axial, equatorial, or a general point.
Difficulty: Difficult
Concept Tested: Properties of magnetic field lines
Detailed Explanation: If two field lines intersect, there would be two directions of magnetic field at the same point, which is impossible.
Common trap: Students often choose formula without checking whether the point is axial, equatorial, or a general point.
JEE Advanced Multiple Correct Question 25For a short bar magnet, the magnetic field at an axial point and equatorial point at the same distance are in the ratio
A) 1 : 1
B) 2 : 1
C) 1 : 2
D) 4 : 1
Correct Answer: B
Difficulty: Difficult
Concept Tested: Axial and equatorial field comparison
Detailed Explanation: For a short magnet, B_axial = (μ₀/4π)(2M/r³) and B_equatorial = (μ₀/4π)(M/r³). Hence ratio is 2:1.
Common trap: Students often choose formula without checking whether the point is axial, equatorial, or a general point.
Difficulty: Difficult
Concept Tested: Axial and equatorial field comparison
Detailed Explanation: For a short magnet, B_axial = (μ₀/4π)(2M/r³) and B_equatorial = (μ₀/4π)(M/r³). Hence ratio is 2:1.
Common trap: Students often choose formula without checking whether the point is axial, equatorial, or a general point.
JEE Advanced Multiple Correct Question 26A bar magnet is broken into two equal pieces perpendicular to its length. Which statement is correct?
A) Each piece has only one pole
B) Magnetic monopoles are formed
C) Each piece is a complete magnet
D) Magnetic moment becomes zero
Correct Answer: C
Difficulty: Difficult
Concept Tested: Broken magnet
Detailed Explanation: Every broken piece again has north and south poles. Magnetic monopoles are not produced by breaking a magnet.
Common trap: Students often choose formula without checking whether the point is axial, equatorial, or a general point.
Difficulty: Difficult
Concept Tested: Broken magnet
Detailed Explanation: Every broken piece again has north and south poles. Magnetic monopoles are not produced by breaking a magnet.
Common trap: Students often choose formula without checking whether the point is axial, equatorial, or a general point.
JEE Advanced Multiple Correct Question 27Net magnetic flux through any closed surface is
A) μ₀ times magnetic pole inside
B) zero
C) BA always
D) infinite for a bar magnet
Correct Answer: B
Difficulty: Difficult
Concept Tested: Gauss law of magnetism
Detailed Explanation: Gauss law of magnetism gives ∮B·dA = 0 because magnetic monopoles do not exist.
Common trap: Students often choose formula without checking whether the point is axial, equatorial, or a general point.
Difficulty: Difficult
Concept Tested: Gauss law of magnetism
Detailed Explanation: Gauss law of magnetism gives ∮B·dA = 0 because magnetic monopoles do not exist.
Common trap: Students often choose formula without checking whether the point is axial, equatorial, or a general point.
JEE Advanced Multiple Correct Question 28A magnetic dipole is in stable equilibrium when angle between M and B is
A) 0°
B) 90°
C) 180°
D) 270°
Correct Answer: A
Difficulty: Difficult
Concept Tested: Magnetic potential energy
Detailed Explanation: Potential energy U = -MB cosθ is minimum at θ = 0°, so equilibrium is stable.
Common trap: Students often choose formula without checking whether the point is axial, equatorial, or a general point.
Difficulty: Difficult
Concept Tested: Magnetic potential energy
Detailed Explanation: Potential energy U = -MB cosθ is minimum at θ = 0°, so equilibrium is stable.
Common trap: Students often choose formula without checking whether the point is axial, equatorial, or a general point.
JEE Advanced Multiple Correct Question 29Torque on a magnetic dipole in uniform magnetic field is maximum when θ is
A) 0°
B) 45°
C) 90°
D) 180°
Correct Answer: C
Difficulty: Difficult
Concept Tested: Torque on dipole
Detailed Explanation: τ = MB sinθ is maximum when sinθ = 1, i.e. θ = 90°.
Common trap: Students often choose formula without checking whether the point is axial, equatorial, or a general point.
Difficulty: Difficult
Concept Tested: Torque on dipole
Detailed Explanation: τ = MB sinθ is maximum when sinθ = 1, i.e. θ = 90°.
Common trap: Students often choose formula without checking whether the point is axial, equatorial, or a general point.
JEE Advanced Multiple Correct Question 30Direction of magnetic moment of a bar magnet is
A) N to S outside the magnet
B) S to N inside the magnet
C) Always downward
D) Opposite to magnetic field lines everywhere
Correct Answer: B
Difficulty: Difficult
Concept Tested: Magnetic moment direction
Detailed Explanation: Magnetic moment vector is directed from south pole to north pole inside the magnet.
Common trap: Students often choose formula without checking whether the point is axial, equatorial, or a general point.
Difficulty: Difficult
Concept Tested: Magnetic moment direction
Detailed Explanation: Magnetic moment vector is directed from south pole to north pole inside the magnet.
Common trap: Students often choose formula without checking whether the point is axial, equatorial, or a general point.
D. JEE Advanced Integer-Type Questions
JEE Advanced Integer Question 1For a short bar magnet, the magnetic field at an axial point and equatorial point at the same distance are in the ratio
A) 1 : 1
B) 2 : 1
C) 1 : 2
D) 4 : 1
Correct Answer: B
Difficulty: Difficult
Concept Tested: Axial and equatorial field comparison
Detailed Explanation: For a short magnet, B_axial = (μ₀/4π)(2M/r³) and B_equatorial = (μ₀/4π)(M/r³). Hence ratio is 2:1.
Common trap: Students often choose formula without checking whether the point is axial, equatorial, or a general point.
Difficulty: Difficult
Concept Tested: Axial and equatorial field comparison
Detailed Explanation: For a short magnet, B_axial = (μ₀/4π)(2M/r³) and B_equatorial = (μ₀/4π)(M/r³). Hence ratio is 2:1.
Common trap: Students often choose formula without checking whether the point is axial, equatorial, or a general point.
JEE Advanced Integer Question 2A bar magnet is broken into two equal pieces perpendicular to its length. Which statement is correct?
A) Each piece has only one pole
B) Magnetic monopoles are formed
C) Each piece is a complete magnet
D) Magnetic moment becomes zero
Correct Answer: C
Difficulty: Difficult
Concept Tested: Broken magnet
Detailed Explanation: Every broken piece again has north and south poles. Magnetic monopoles are not produced by breaking a magnet.
Common trap: Students often choose formula without checking whether the point is axial, equatorial, or a general point.
Difficulty: Difficult
Concept Tested: Broken magnet
Detailed Explanation: Every broken piece again has north and south poles. Magnetic monopoles are not produced by breaking a magnet.
Common trap: Students often choose formula without checking whether the point is axial, equatorial, or a general point.
JEE Advanced Integer Question 3Net magnetic flux through any closed surface is
A) μ₀ times magnetic pole inside
B) zero
C) BA always
D) infinite for a bar magnet
Correct Answer: B
Difficulty: Difficult
Concept Tested: Gauss law of magnetism
Detailed Explanation: Gauss law of magnetism gives ∮B·dA = 0 because magnetic monopoles do not exist.
Common trap: Students often choose formula without checking whether the point is axial, equatorial, or a general point.
Difficulty: Difficult
Concept Tested: Gauss law of magnetism
Detailed Explanation: Gauss law of magnetism gives ∮B·dA = 0 because magnetic monopoles do not exist.
Common trap: Students often choose formula without checking whether the point is axial, equatorial, or a general point.
JEE Advanced Integer Question 4A magnetic dipole is in stable equilibrium when angle between M and B is
A) 0°
B) 90°
C) 180°
D) 270°
Correct Answer: A
Difficulty: Difficult
Concept Tested: Magnetic potential energy
Detailed Explanation: Potential energy U = -MB cosθ is minimum at θ = 0°, so equilibrium is stable.
Common trap: Students often choose formula without checking whether the point is axial, equatorial, or a general point.
Difficulty: Difficult
Concept Tested: Magnetic potential energy
Detailed Explanation: Potential energy U = -MB cosθ is minimum at θ = 0°, so equilibrium is stable.
Common trap: Students often choose formula without checking whether the point is axial, equatorial, or a general point.
JEE Advanced Integer Question 5Torque on a magnetic dipole in uniform magnetic field is maximum when θ is
A) 0°
B) 45°
C) 90°
D) 180°
Correct Answer: C
Difficulty: Difficult
Concept Tested: Torque on dipole
Detailed Explanation: τ = MB sinθ is maximum when sinθ = 1, i.e. θ = 90°.
Common trap: Students often choose formula without checking whether the point is axial, equatorial, or a general point.
Difficulty: Difficult
Concept Tested: Torque on dipole
Detailed Explanation: τ = MB sinθ is maximum when sinθ = 1, i.e. θ = 90°.
Common trap: Students often choose formula without checking whether the point is axial, equatorial, or a general point.
JEE Advanced Integer Question 6Direction of magnetic moment of a bar magnet is
A) N to S outside the magnet
B) S to N inside the magnet
C) Always downward
D) Opposite to magnetic field lines everywhere
Correct Answer: B
Difficulty: Difficult
Concept Tested: Magnetic moment direction
Detailed Explanation: Magnetic moment vector is directed from south pole to north pole inside the magnet.
Common trap: Students often choose formula without checking whether the point is axial, equatorial, or a general point.
Difficulty: Difficult
Concept Tested: Magnetic moment direction
Detailed Explanation: Magnetic moment vector is directed from south pole to north pole inside the magnet.
Common trap: Students often choose formula without checking whether the point is axial, equatorial, or a general point.
JEE Advanced Integer Question 7If distance from a short magnet is doubled, axial magnetic field becomes
A) 1/2
B) 1/4
C) 1/8
D) 1/16
Correct Answer: C
Difficulty: Difficult
Concept Tested: Short magnet inverse-cube law
Detailed Explanation: For a short magnet, B_axial ∝ 1/r³. Doubling r makes field 1/8.
Common trap: Students often choose formula without checking whether the point is axial, equatorial, or a general point.
Difficulty: Difficult
Concept Tested: Short magnet inverse-cube law
Detailed Explanation: For a short magnet, B_axial ∝ 1/r³. Doubling r makes field 1/8.
Common trap: Students often choose formula without checking whether the point is axial, equatorial, or a general point.
JEE Advanced Integer Question 8Magnetic field lines never intersect because
A) they are imaginary
B) magnetic field has unique direction at a point
C) monopoles exist
D) field is scalar
Correct Answer: B
Difficulty: Difficult
Concept Tested: Properties of magnetic field lines
Detailed Explanation: If two field lines intersect, there would be two directions of magnetic field at the same point, which is impossible.
Common trap: Students often choose formula without checking whether the point is axial, equatorial, or a general point.
Difficulty: Difficult
Concept Tested: Properties of magnetic field lines
Detailed Explanation: If two field lines intersect, there would be two directions of magnetic field at the same point, which is impossible.
Common trap: Students often choose formula without checking whether the point is axial, equatorial, or a general point.
JEE Advanced Integer Question 9For a short bar magnet, the magnetic field at an axial point and equatorial point at the same distance are in the ratio
A) 1 : 1
B) 2 : 1
C) 1 : 2
D) 4 : 1
Correct Answer: B
Difficulty: Difficult
Concept Tested: Axial and equatorial field comparison
Detailed Explanation: For a short magnet, B_axial = (μ₀/4π)(2M/r³) and B_equatorial = (μ₀/4π)(M/r³). Hence ratio is 2:1.
Common trap: Students often choose formula without checking whether the point is axial, equatorial, or a general point.
Difficulty: Difficult
Concept Tested: Axial and equatorial field comparison
Detailed Explanation: For a short magnet, B_axial = (μ₀/4π)(2M/r³) and B_equatorial = (μ₀/4π)(M/r³). Hence ratio is 2:1.
Common trap: Students often choose formula without checking whether the point is axial, equatorial, or a general point.
JEE Advanced Integer Question 10A bar magnet is broken into two equal pieces perpendicular to its length. Which statement is correct?
A) Each piece has only one pole
B) Magnetic monopoles are formed
C) Each piece is a complete magnet
D) Magnetic moment becomes zero
Correct Answer: C
Difficulty: Difficult
Concept Tested: Broken magnet
Detailed Explanation: Every broken piece again has north and south poles. Magnetic monopoles are not produced by breaking a magnet.
Common trap: Students often choose formula without checking whether the point is axial, equatorial, or a general point.
Difficulty: Difficult
Concept Tested: Broken magnet
Detailed Explanation: Every broken piece again has north and south poles. Magnetic monopoles are not produced by breaking a magnet.
Common trap: Students often choose formula without checking whether the point is axial, equatorial, or a general point.
JEE Advanced Integer Question 11Net magnetic flux through any closed surface is
A) μ₀ times magnetic pole inside
B) zero
C) BA always
D) infinite for a bar magnet
Correct Answer: B
Difficulty: Difficult
Concept Tested: Gauss law of magnetism
Detailed Explanation: Gauss law of magnetism gives ∮B·dA = 0 because magnetic monopoles do not exist.
Common trap: Students often choose formula without checking whether the point is axial, equatorial, or a general point.
Difficulty: Difficult
Concept Tested: Gauss law of magnetism
Detailed Explanation: Gauss law of magnetism gives ∮B·dA = 0 because magnetic monopoles do not exist.
Common trap: Students often choose formula without checking whether the point is axial, equatorial, or a general point.
JEE Advanced Integer Question 12A magnetic dipole is in stable equilibrium when angle between M and B is
A) 0°
B) 90°
C) 180°
D) 270°
Correct Answer: A
Difficulty: Difficult
Concept Tested: Magnetic potential energy
Detailed Explanation: Potential energy U = -MB cosθ is minimum at θ = 0°, so equilibrium is stable.
Common trap: Students often choose formula without checking whether the point is axial, equatorial, or a general point.
Difficulty: Difficult
Concept Tested: Magnetic potential energy
Detailed Explanation: Potential energy U = -MB cosθ is minimum at θ = 0°, so equilibrium is stable.
Common trap: Students often choose formula without checking whether the point is axial, equatorial, or a general point.
JEE Advanced Integer Question 13Torque on a magnetic dipole in uniform magnetic field is maximum when θ is
A) 0°
B) 45°
C) 90°
D) 180°
Correct Answer: C
Difficulty: Difficult
Concept Tested: Torque on dipole
Detailed Explanation: τ = MB sinθ is maximum when sinθ = 1, i.e. θ = 90°.
Common trap: Students often choose formula without checking whether the point is axial, equatorial, or a general point.
Difficulty: Difficult
Concept Tested: Torque on dipole
Detailed Explanation: τ = MB sinθ is maximum when sinθ = 1, i.e. θ = 90°.
Common trap: Students often choose formula without checking whether the point is axial, equatorial, or a general point.
JEE Advanced Integer Question 14Direction of magnetic moment of a bar magnet is
A) N to S outside the magnet
B) S to N inside the magnet
C) Always downward
D) Opposite to magnetic field lines everywhere
Correct Answer: B
Difficulty: Difficult
Concept Tested: Magnetic moment direction
Detailed Explanation: Magnetic moment vector is directed from south pole to north pole inside the magnet.
Common trap: Students often choose formula without checking whether the point is axial, equatorial, or a general point.
Difficulty: Difficult
Concept Tested: Magnetic moment direction
Detailed Explanation: Magnetic moment vector is directed from south pole to north pole inside the magnet.
Common trap: Students often choose formula without checking whether the point is axial, equatorial, or a general point.
JEE Advanced Integer Question 15If distance from a short magnet is doubled, axial magnetic field becomes
A) 1/2
B) 1/4
C) 1/8
D) 1/16
Correct Answer: C
Difficulty: Difficult
Concept Tested: Short magnet inverse-cube law
Detailed Explanation: For a short magnet, B_axial ∝ 1/r³. Doubling r makes field 1/8.
Common trap: Students often choose formula without checking whether the point is axial, equatorial, or a general point.
Difficulty: Difficult
Concept Tested: Short magnet inverse-cube law
Detailed Explanation: For a short magnet, B_axial ∝ 1/r³. Doubling r makes field 1/8.
Common trap: Students often choose formula without checking whether the point is axial, equatorial, or a general point.
JEE Advanced Integer Question 16Magnetic field lines never intersect because
A) they are imaginary
B) magnetic field has unique direction at a point
C) monopoles exist
D) field is scalar
Correct Answer: B
Difficulty: Difficult
Concept Tested: Properties of magnetic field lines
Detailed Explanation: If two field lines intersect, there would be two directions of magnetic field at the same point, which is impossible.
Common trap: Students often choose formula without checking whether the point is axial, equatorial, or a general point.
Difficulty: Difficult
Concept Tested: Properties of magnetic field lines
Detailed Explanation: If two field lines intersect, there would be two directions of magnetic field at the same point, which is impossible.
Common trap: Students often choose formula without checking whether the point is axial, equatorial, or a general point.
JEE Advanced Integer Question 17For a short bar magnet, the magnetic field at an axial point and equatorial point at the same distance are in the ratio
A) 1 : 1
B) 2 : 1
C) 1 : 2
D) 4 : 1
Correct Answer: B
Difficulty: Difficult
Concept Tested: Axial and equatorial field comparison
Detailed Explanation: For a short magnet, B_axial = (μ₀/4π)(2M/r³) and B_equatorial = (μ₀/4π)(M/r³). Hence ratio is 2:1.
Common trap: Students often choose formula without checking whether the point is axial, equatorial, or a general point.
Difficulty: Difficult
Concept Tested: Axial and equatorial field comparison
Detailed Explanation: For a short magnet, B_axial = (μ₀/4π)(2M/r³) and B_equatorial = (μ₀/4π)(M/r³). Hence ratio is 2:1.
Common trap: Students often choose formula without checking whether the point is axial, equatorial, or a general point.
JEE Advanced Integer Question 18A bar magnet is broken into two equal pieces perpendicular to its length. Which statement is correct?
A) Each piece has only one pole
B) Magnetic monopoles are formed
C) Each piece is a complete magnet
D) Magnetic moment becomes zero
Correct Answer: C
Difficulty: Difficult
Concept Tested: Broken magnet
Detailed Explanation: Every broken piece again has north and south poles. Magnetic monopoles are not produced by breaking a magnet.
Common trap: Students often choose formula without checking whether the point is axial, equatorial, or a general point.
Difficulty: Difficult
Concept Tested: Broken magnet
Detailed Explanation: Every broken piece again has north and south poles. Magnetic monopoles are not produced by breaking a magnet.
Common trap: Students often choose formula without checking whether the point is axial, equatorial, or a general point.
JEE Advanced Integer Question 19Net magnetic flux through any closed surface is
A) μ₀ times magnetic pole inside
B) zero
C) BA always
D) infinite for a bar magnet
Correct Answer: B
Difficulty: Difficult
Concept Tested: Gauss law of magnetism
Detailed Explanation: Gauss law of magnetism gives ∮B·dA = 0 because magnetic monopoles do not exist.
Common trap: Students often choose formula without checking whether the point is axial, equatorial, or a general point.
Difficulty: Difficult
Concept Tested: Gauss law of magnetism
Detailed Explanation: Gauss law of magnetism gives ∮B·dA = 0 because magnetic monopoles do not exist.
Common trap: Students often choose formula without checking whether the point is axial, equatorial, or a general point.
JEE Advanced Integer Question 20A magnetic dipole is in stable equilibrium when angle between M and B is
A) 0°
B) 90°
C) 180°
D) 270°
Correct Answer: A
Difficulty: Difficult
Concept Tested: Magnetic potential energy
Detailed Explanation: Potential energy U = -MB cosθ is minimum at θ = 0°, so equilibrium is stable.
Common trap: Students often choose formula without checking whether the point is axial, equatorial, or a general point.
Difficulty: Difficult
Concept Tested: Magnetic potential energy
Detailed Explanation: Potential energy U = -MB cosθ is minimum at θ = 0°, so equilibrium is stable.
Common trap: Students often choose formula without checking whether the point is axial, equatorial, or a general point.
D. JEE Advanced Matrix-Match Questions
JEE Advanced Matrix Match Question 1For a short bar magnet, the magnetic field at an axial point and equatorial point at the same distance are in the ratio
A) 1 : 1
B) 2 : 1
C) 1 : 2
D) 4 : 1
Correct Answer: B
Difficulty: Difficult
Concept Tested: Axial and equatorial field comparison
Detailed Explanation: For a short magnet, B_axial = (μ₀/4π)(2M/r³) and B_equatorial = (μ₀/4π)(M/r³). Hence ratio is 2:1.
Common trap: Students often choose formula without checking whether the point is axial, equatorial, or a general point.
Difficulty: Difficult
Concept Tested: Axial and equatorial field comparison
Detailed Explanation: For a short magnet, B_axial = (μ₀/4π)(2M/r³) and B_equatorial = (μ₀/4π)(M/r³). Hence ratio is 2:1.
Common trap: Students often choose formula without checking whether the point is axial, equatorial, or a general point.
JEE Advanced Matrix Match Question 2A bar magnet is broken into two equal pieces perpendicular to its length. Which statement is correct?
A) Each piece has only one pole
B) Magnetic monopoles are formed
C) Each piece is a complete magnet
D) Magnetic moment becomes zero
Correct Answer: C
Difficulty: Difficult
Concept Tested: Broken magnet
Detailed Explanation: Every broken piece again has north and south poles. Magnetic monopoles are not produced by breaking a magnet.
Common trap: Students often choose formula without checking whether the point is axial, equatorial, or a general point.
Difficulty: Difficult
Concept Tested: Broken magnet
Detailed Explanation: Every broken piece again has north and south poles. Magnetic monopoles are not produced by breaking a magnet.
Common trap: Students often choose formula without checking whether the point is axial, equatorial, or a general point.
JEE Advanced Matrix Match Question 3Net magnetic flux through any closed surface is
A) μ₀ times magnetic pole inside
B) zero
C) BA always
D) infinite for a bar magnet
Correct Answer: B
Difficulty: Difficult
Concept Tested: Gauss law of magnetism
Detailed Explanation: Gauss law of magnetism gives ∮B·dA = 0 because magnetic monopoles do not exist.
Common trap: Students often choose formula without checking whether the point is axial, equatorial, or a general point.
Difficulty: Difficult
Concept Tested: Gauss law of magnetism
Detailed Explanation: Gauss law of magnetism gives ∮B·dA = 0 because magnetic monopoles do not exist.
Common trap: Students often choose formula without checking whether the point is axial, equatorial, or a general point.
JEE Advanced Matrix Match Question 4A magnetic dipole is in stable equilibrium when angle between M and B is
A) 0°
B) 90°
C) 180°
D) 270°
Correct Answer: A
Difficulty: Difficult
Concept Tested: Magnetic potential energy
Detailed Explanation: Potential energy U = -MB cosθ is minimum at θ = 0°, so equilibrium is stable.
Common trap: Students often choose formula without checking whether the point is axial, equatorial, or a general point.
Difficulty: Difficult
Concept Tested: Magnetic potential energy
Detailed Explanation: Potential energy U = -MB cosθ is minimum at θ = 0°, so equilibrium is stable.
Common trap: Students often choose formula without checking whether the point is axial, equatorial, or a general point.
JEE Advanced Matrix Match Question 5Torque on a magnetic dipole in uniform magnetic field is maximum when θ is
A) 0°
B) 45°
C) 90°
D) 180°
Correct Answer: C
Difficulty: Difficult
Concept Tested: Torque on dipole
Detailed Explanation: τ = MB sinθ is maximum when sinθ = 1, i.e. θ = 90°.
Common trap: Students often choose formula without checking whether the point is axial, equatorial, or a general point.
Difficulty: Difficult
Concept Tested: Torque on dipole
Detailed Explanation: τ = MB sinθ is maximum when sinθ = 1, i.e. θ = 90°.
Common trap: Students often choose formula without checking whether the point is axial, equatorial, or a general point.
JEE Advanced Matrix Match Question 6Direction of magnetic moment of a bar magnet is
A) N to S outside the magnet
B) S to N inside the magnet
C) Always downward
D) Opposite to magnetic field lines everywhere
Correct Answer: B
Difficulty: Difficult
Concept Tested: Magnetic moment direction
Detailed Explanation: Magnetic moment vector is directed from south pole to north pole inside the magnet.
Common trap: Students often choose formula without checking whether the point is axial, equatorial, or a general point.
Difficulty: Difficult
Concept Tested: Magnetic moment direction
Detailed Explanation: Magnetic moment vector is directed from south pole to north pole inside the magnet.
Common trap: Students often choose formula without checking whether the point is axial, equatorial, or a general point.
JEE Advanced Matrix Match Question 7If distance from a short magnet is doubled, axial magnetic field becomes
A) 1/2
B) 1/4
C) 1/8
D) 1/16
Correct Answer: C
Difficulty: Difficult
Concept Tested: Short magnet inverse-cube law
Detailed Explanation: For a short magnet, B_axial ∝ 1/r³. Doubling r makes field 1/8.
Common trap: Students often choose formula without checking whether the point is axial, equatorial, or a general point.
Difficulty: Difficult
Concept Tested: Short magnet inverse-cube law
Detailed Explanation: For a short magnet, B_axial ∝ 1/r³. Doubling r makes field 1/8.
Common trap: Students often choose formula without checking whether the point is axial, equatorial, or a general point.
JEE Advanced Matrix Match Question 8Magnetic field lines never intersect because
A) they are imaginary
B) magnetic field has unique direction at a point
C) monopoles exist
D) field is scalar
Correct Answer: B
Difficulty: Difficult
Concept Tested: Properties of magnetic field lines
Detailed Explanation: If two field lines intersect, there would be two directions of magnetic field at the same point, which is impossible.
Common trap: Students often choose formula without checking whether the point is axial, equatorial, or a general point.
Difficulty: Difficult
Concept Tested: Properties of magnetic field lines
Detailed Explanation: If two field lines intersect, there would be two directions of magnetic field at the same point, which is impossible.
Common trap: Students often choose formula without checking whether the point is axial, equatorial, or a general point.
JEE Advanced Matrix Match Question 9For a short bar magnet, the magnetic field at an axial point and equatorial point at the same distance are in the ratio
A) 1 : 1
B) 2 : 1
C) 1 : 2
D) 4 : 1
Correct Answer: B
Difficulty: Difficult
Concept Tested: Axial and equatorial field comparison
Detailed Explanation: For a short magnet, B_axial = (μ₀/4π)(2M/r³) and B_equatorial = (μ₀/4π)(M/r³). Hence ratio is 2:1.
Common trap: Students often choose formula without checking whether the point is axial, equatorial, or a general point.
Difficulty: Difficult
Concept Tested: Axial and equatorial field comparison
Detailed Explanation: For a short magnet, B_axial = (μ₀/4π)(2M/r³) and B_equatorial = (μ₀/4π)(M/r³). Hence ratio is 2:1.
Common trap: Students often choose formula without checking whether the point is axial, equatorial, or a general point.
JEE Advanced Matrix Match Question 10A bar magnet is broken into two equal pieces perpendicular to its length. Which statement is correct?
A) Each piece has only one pole
B) Magnetic monopoles are formed
C) Each piece is a complete magnet
D) Magnetic moment becomes zero
Correct Answer: C
Difficulty: Difficult
Concept Tested: Broken magnet
Detailed Explanation: Every broken piece again has north and south poles. Magnetic monopoles are not produced by breaking a magnet.
Common trap: Students often choose formula without checking whether the point is axial, equatorial, or a general point.
Difficulty: Difficult
Concept Tested: Broken magnet
Detailed Explanation: Every broken piece again has north and south poles. Magnetic monopoles are not produced by breaking a magnet.
Common trap: Students often choose formula without checking whether the point is axial, equatorial, or a general point.
JEE Advanced Matrix Match Question 11Net magnetic flux through any closed surface is
A) μ₀ times magnetic pole inside
B) zero
C) BA always
D) infinite for a bar magnet
Correct Answer: B
Difficulty: Difficult
Concept Tested: Gauss law of magnetism
Detailed Explanation: Gauss law of magnetism gives ∮B·dA = 0 because magnetic monopoles do not exist.
Common trap: Students often choose formula without checking whether the point is axial, equatorial, or a general point.
Difficulty: Difficult
Concept Tested: Gauss law of magnetism
Detailed Explanation: Gauss law of magnetism gives ∮B·dA = 0 because magnetic monopoles do not exist.
Common trap: Students often choose formula without checking whether the point is axial, equatorial, or a general point.
JEE Advanced Matrix Match Question 12A magnetic dipole is in stable equilibrium when angle between M and B is
A) 0°
B) 90°
C) 180°
D) 270°
Correct Answer: A
Difficulty: Difficult
Concept Tested: Magnetic potential energy
Detailed Explanation: Potential energy U = -MB cosθ is minimum at θ = 0°, so equilibrium is stable.
Common trap: Students often choose formula without checking whether the point is axial, equatorial, or a general point.
Difficulty: Difficult
Concept Tested: Magnetic potential energy
Detailed Explanation: Potential energy U = -MB cosθ is minimum at θ = 0°, so equilibrium is stable.
Common trap: Students often choose formula without checking whether the point is axial, equatorial, or a general point.
JEE Advanced Matrix Match Question 13Torque on a magnetic dipole in uniform magnetic field is maximum when θ is
A) 0°
B) 45°
C) 90°
D) 180°
Correct Answer: C
Difficulty: Difficult
Concept Tested: Torque on dipole
Detailed Explanation: τ = MB sinθ is maximum when sinθ = 1, i.e. θ = 90°.
Common trap: Students often choose formula without checking whether the point is axial, equatorial, or a general point.
Difficulty: Difficult
Concept Tested: Torque on dipole
Detailed Explanation: τ = MB sinθ is maximum when sinθ = 1, i.e. θ = 90°.
Common trap: Students often choose formula without checking whether the point is axial, equatorial, or a general point.
JEE Advanced Matrix Match Question 14Direction of magnetic moment of a bar magnet is
A) N to S outside the magnet
B) S to N inside the magnet
C) Always downward
D) Opposite to magnetic field lines everywhere
Correct Answer: B
Difficulty: Difficult
Concept Tested: Magnetic moment direction
Detailed Explanation: Magnetic moment vector is directed from south pole to north pole inside the magnet.
Common trap: Students often choose formula without checking whether the point is axial, equatorial, or a general point.
Difficulty: Difficult
Concept Tested: Magnetic moment direction
Detailed Explanation: Magnetic moment vector is directed from south pole to north pole inside the magnet.
Common trap: Students often choose formula without checking whether the point is axial, equatorial, or a general point.
JEE Advanced Matrix Match Question 15If distance from a short magnet is doubled, axial magnetic field becomes
A) 1/2
B) 1/4
C) 1/8
D) 1/16
Correct Answer: C
Difficulty: Difficult
Concept Tested: Short magnet inverse-cube law
Detailed Explanation: For a short magnet, B_axial ∝ 1/r³. Doubling r makes field 1/8.
Common trap: Students often choose formula without checking whether the point is axial, equatorial, or a general point.
Difficulty: Difficult
Concept Tested: Short magnet inverse-cube law
Detailed Explanation: For a short magnet, B_axial ∝ 1/r³. Doubling r makes field 1/8.
Common trap: Students often choose formula without checking whether the point is axial, equatorial, or a general point.
D. JEE Advanced Paragraph-Type Questions
JEE Advanced Paragraph Question 1For a short bar magnet, the magnetic field at an axial point and equatorial point at the same distance are in the ratio
A) 1 : 1
B) 2 : 1
C) 1 : 2
D) 4 : 1
Correct Answer: B
Difficulty: Difficult
Concept Tested: Axial and equatorial field comparison
Detailed Explanation: For a short magnet, B_axial = (μ₀/4π)(2M/r³) and B_equatorial = (μ₀/4π)(M/r³). Hence ratio is 2:1.
Common trap: Students often choose formula without checking whether the point is axial, equatorial, or a general point.
Difficulty: Difficult
Concept Tested: Axial and equatorial field comparison
Detailed Explanation: For a short magnet, B_axial = (μ₀/4π)(2M/r³) and B_equatorial = (μ₀/4π)(M/r³). Hence ratio is 2:1.
Common trap: Students often choose formula without checking whether the point is axial, equatorial, or a general point.
JEE Advanced Paragraph Question 2A bar magnet is broken into two equal pieces perpendicular to its length. Which statement is correct?
A) Each piece has only one pole
B) Magnetic monopoles are formed
C) Each piece is a complete magnet
D) Magnetic moment becomes zero
Correct Answer: C
Difficulty: Difficult
Concept Tested: Broken magnet
Detailed Explanation: Every broken piece again has north and south poles. Magnetic monopoles are not produced by breaking a magnet.
Common trap: Students often choose formula without checking whether the point is axial, equatorial, or a general point.
Difficulty: Difficult
Concept Tested: Broken magnet
Detailed Explanation: Every broken piece again has north and south poles. Magnetic monopoles are not produced by breaking a magnet.
Common trap: Students often choose formula without checking whether the point is axial, equatorial, or a general point.
JEE Advanced Paragraph Question 3Net magnetic flux through any closed surface is
A) μ₀ times magnetic pole inside
B) zero
C) BA always
D) infinite for a bar magnet
Correct Answer: B
Difficulty: Difficult
Concept Tested: Gauss law of magnetism
Detailed Explanation: Gauss law of magnetism gives ∮B·dA = 0 because magnetic monopoles do not exist.
Common trap: Students often choose formula without checking whether the point is axial, equatorial, or a general point.
Difficulty: Difficult
Concept Tested: Gauss law of magnetism
Detailed Explanation: Gauss law of magnetism gives ∮B·dA = 0 because magnetic monopoles do not exist.
Common trap: Students often choose formula without checking whether the point is axial, equatorial, or a general point.
JEE Advanced Paragraph Question 4A magnetic dipole is in stable equilibrium when angle between M and B is
A) 0°
B) 90°
C) 180°
D) 270°
Correct Answer: A
Difficulty: Difficult
Concept Tested: Magnetic potential energy
Detailed Explanation: Potential energy U = -MB cosθ is minimum at θ = 0°, so equilibrium is stable.
Common trap: Students often choose formula without checking whether the point is axial, equatorial, or a general point.
Difficulty: Difficult
Concept Tested: Magnetic potential energy
Detailed Explanation: Potential energy U = -MB cosθ is minimum at θ = 0°, so equilibrium is stable.
Common trap: Students often choose formula without checking whether the point is axial, equatorial, or a general point.
JEE Advanced Paragraph Question 5Torque on a magnetic dipole in uniform magnetic field is maximum when θ is
A) 0°
B) 45°
C) 90°
D) 180°
Correct Answer: C
Difficulty: Difficult
Concept Tested: Torque on dipole
Detailed Explanation: τ = MB sinθ is maximum when sinθ = 1, i.e. θ = 90°.
Common trap: Students often choose formula without checking whether the point is axial, equatorial, or a general point.
Difficulty: Difficult
Concept Tested: Torque on dipole
Detailed Explanation: τ = MB sinθ is maximum when sinθ = 1, i.e. θ = 90°.
Common trap: Students often choose formula without checking whether the point is axial, equatorial, or a general point.
JEE Advanced Paragraph Question 6Direction of magnetic moment of a bar magnet is
A) N to S outside the magnet
B) S to N inside the magnet
C) Always downward
D) Opposite to magnetic field lines everywhere
Correct Answer: B
Difficulty: Difficult
Concept Tested: Magnetic moment direction
Detailed Explanation: Magnetic moment vector is directed from south pole to north pole inside the magnet.
Common trap: Students often choose formula without checking whether the point is axial, equatorial, or a general point.
Difficulty: Difficult
Concept Tested: Magnetic moment direction
Detailed Explanation: Magnetic moment vector is directed from south pole to north pole inside the magnet.
Common trap: Students often choose formula without checking whether the point is axial, equatorial, or a general point.
JEE Advanced Paragraph Question 7If distance from a short magnet is doubled, axial magnetic field becomes
A) 1/2
B) 1/4
C) 1/8
D) 1/16
Correct Answer: C
Difficulty: Difficult
Concept Tested: Short magnet inverse-cube law
Detailed Explanation: For a short magnet, B_axial ∝ 1/r³. Doubling r makes field 1/8.
Common trap: Students often choose formula without checking whether the point is axial, equatorial, or a general point.
Difficulty: Difficult
Concept Tested: Short magnet inverse-cube law
Detailed Explanation: For a short magnet, B_axial ∝ 1/r³. Doubling r makes field 1/8.
Common trap: Students often choose formula without checking whether the point is axial, equatorial, or a general point.
JEE Advanced Paragraph Question 8Magnetic field lines never intersect because
A) they are imaginary
B) magnetic field has unique direction at a point
C) monopoles exist
D) field is scalar
Correct Answer: B
Difficulty: Difficult
Concept Tested: Properties of magnetic field lines
Detailed Explanation: If two field lines intersect, there would be two directions of magnetic field at the same point, which is impossible.
Common trap: Students often choose formula without checking whether the point is axial, equatorial, or a general point.
Difficulty: Difficult
Concept Tested: Properties of magnetic field lines
Detailed Explanation: If two field lines intersect, there would be two directions of magnetic field at the same point, which is impossible.
Common trap: Students often choose formula without checking whether the point is axial, equatorial, or a general point.
JEE Advanced Paragraph Question 9For a short bar magnet, the magnetic field at an axial point and equatorial point at the same distance are in the ratio
A) 1 : 1
B) 2 : 1
C) 1 : 2
D) 4 : 1
Correct Answer: B
Difficulty: Difficult
Concept Tested: Axial and equatorial field comparison
Detailed Explanation: For a short magnet, B_axial = (μ₀/4π)(2M/r³) and B_equatorial = (μ₀/4π)(M/r³). Hence ratio is 2:1.
Common trap: Students often choose formula without checking whether the point is axial, equatorial, or a general point.
Difficulty: Difficult
Concept Tested: Axial and equatorial field comparison
Detailed Explanation: For a short magnet, B_axial = (μ₀/4π)(2M/r³) and B_equatorial = (μ₀/4π)(M/r³). Hence ratio is 2:1.
Common trap: Students often choose formula without checking whether the point is axial, equatorial, or a general point.
JEE Advanced Paragraph Question 10A bar magnet is broken into two equal pieces perpendicular to its length. Which statement is correct?
A) Each piece has only one pole
B) Magnetic monopoles are formed
C) Each piece is a complete magnet
D) Magnetic moment becomes zero
Correct Answer: C
Difficulty: Difficult
Concept Tested: Broken magnet
Detailed Explanation: Every broken piece again has north and south poles. Magnetic monopoles are not produced by breaking a magnet.
Common trap: Students often choose formula without checking whether the point is axial, equatorial, or a general point.
Difficulty: Difficult
Concept Tested: Broken magnet
Detailed Explanation: Every broken piece again has north and south poles. Magnetic monopoles are not produced by breaking a magnet.
Common trap: Students often choose formula without checking whether the point is axial, equatorial, or a general point.
JEE Advanced Paragraph Question 11Net magnetic flux through any closed surface is
A) μ₀ times magnetic pole inside
B) zero
C) BA always
D) infinite for a bar magnet
Correct Answer: B
Difficulty: Difficult
Concept Tested: Gauss law of magnetism
Detailed Explanation: Gauss law of magnetism gives ∮B·dA = 0 because magnetic monopoles do not exist.
Common trap: Students often choose formula without checking whether the point is axial, equatorial, or a general point.
Difficulty: Difficult
Concept Tested: Gauss law of magnetism
Detailed Explanation: Gauss law of magnetism gives ∮B·dA = 0 because magnetic monopoles do not exist.
Common trap: Students often choose formula without checking whether the point is axial, equatorial, or a general point.
JEE Advanced Paragraph Question 12A magnetic dipole is in stable equilibrium when angle between M and B is
A) 0°
B) 90°
C) 180°
D) 270°
Correct Answer: A
Difficulty: Difficult
Concept Tested: Magnetic potential energy
Detailed Explanation: Potential energy U = -MB cosθ is minimum at θ = 0°, so equilibrium is stable.
Common trap: Students often choose formula without checking whether the point is axial, equatorial, or a general point.
Difficulty: Difficult
Concept Tested: Magnetic potential energy
Detailed Explanation: Potential energy U = -MB cosθ is minimum at θ = 0°, so equilibrium is stable.
Common trap: Students often choose formula without checking whether the point is axial, equatorial, or a general point.
JEE Advanced Paragraph Question 13Torque on a magnetic dipole in uniform magnetic field is maximum when θ is
A) 0°
B) 45°
C) 90°
D) 180°
Correct Answer: C
Difficulty: Difficult
Concept Tested: Torque on dipole
Detailed Explanation: τ = MB sinθ is maximum when sinθ = 1, i.e. θ = 90°.
Common trap: Students often choose formula without checking whether the point is axial, equatorial, or a general point.
Difficulty: Difficult
Concept Tested: Torque on dipole
Detailed Explanation: τ = MB sinθ is maximum when sinθ = 1, i.e. θ = 90°.
Common trap: Students often choose formula without checking whether the point is axial, equatorial, or a general point.
JEE Advanced Paragraph Question 14Direction of magnetic moment of a bar magnet is
A) N to S outside the magnet
B) S to N inside the magnet
C) Always downward
D) Opposite to magnetic field lines everywhere
Correct Answer: B
Difficulty: Difficult
Concept Tested: Magnetic moment direction
Detailed Explanation: Magnetic moment vector is directed from south pole to north pole inside the magnet.
Common trap: Students often choose formula without checking whether the point is axial, equatorial, or a general point.
Difficulty: Difficult
Concept Tested: Magnetic moment direction
Detailed Explanation: Magnetic moment vector is directed from south pole to north pole inside the magnet.
Common trap: Students often choose formula without checking whether the point is axial, equatorial, or a general point.
JEE Advanced Paragraph Question 15If distance from a short magnet is doubled, axial magnetic field becomes
A) 1/2
B) 1/4
C) 1/8
D) 1/16
Correct Answer: C
Difficulty: Difficult
Concept Tested: Short magnet inverse-cube law
Detailed Explanation: For a short magnet, B_axial ∝ 1/r³. Doubling r makes field 1/8.
Common trap: Students often choose formula without checking whether the point is axial, equatorial, or a general point.
Difficulty: Difficult
Concept Tested: Short magnet inverse-cube law
Detailed Explanation: For a short magnet, B_axial ∝ 1/r³. Doubling r makes field 1/8.
Common trap: Students often choose formula without checking whether the point is axial, equatorial, or a general point.
E. IB Physics Structured Questions
IB Physics Question 1Explain properties of magnetic field lines with formula and diagram wherever required.
Answer: Write the definition, draw a neat labeled diagram, define all symbols, derive the formula step-by-step if derivation is asked, and finish with physical meaning. For properties of magnetic field lines, the key point is to connect the diagram with the final formula and avoid confusing magnetic pole strength m with magnetic moment M.
IB Physics Question 2Explain bar magnet as an equivalent solenoid with formula and diagram wherever required.
Answer: Write the definition, draw a neat labeled diagram, define all symbols, derive the formula step-by-step if derivation is asked, and finish with physical meaning. For bar magnet as an equivalent solenoid, the key point is to connect the diagram with the final formula and avoid confusing magnetic pole strength m with magnetic moment M.
IB Physics Question 3Explain magnetic moment and pole strength with formula and diagram wherever required.
Answer: Write the definition, draw a neat labeled diagram, define all symbols, derive the formula step-by-step if derivation is asked, and finish with physical meaning. For magnetic moment and pole strength, the key point is to connect the diagram with the final formula and avoid confusing magnetic pole strength m with magnetic moment M.
IB Physics Question 4Explain Coulomb law in magnetism with formula and diagram wherever required.
Answer: Write the definition, draw a neat labeled diagram, define all symbols, derive the formula step-by-step if derivation is asked, and finish with physical meaning. For Coulomb law in magnetism, the key point is to connect the diagram with the final formula and avoid confusing magnetic pole strength m with magnetic moment M.
IB Physics Question 5Explain axial field due to a bar magnet with formula and diagram wherever required.
Answer: Write the definition, draw a neat labeled diagram, define all symbols, derive the formula step-by-step if derivation is asked, and finish with physical meaning. For axial field due to a bar magnet, the key point is to connect the diagram with the final formula and avoid confusing magnetic pole strength m with magnetic moment M.
IB Physics Question 6Explain equatorial field due to a bar magnet with formula and diagram wherever required.
Answer: Write the definition, draw a neat labeled diagram, define all symbols, derive the formula step-by-step if derivation is asked, and finish with physical meaning. For equatorial field due to a bar magnet, the key point is to connect the diagram with the final formula and avoid confusing magnetic pole strength m with magnetic moment M.
IB Physics Question 7Explain torque on magnetic dipole with formula and diagram wherever required.
Answer: Write the definition, draw a neat labeled diagram, define all symbols, derive the formula step-by-step if derivation is asked, and finish with physical meaning. For torque on magnetic dipole, the key point is to connect the diagram with the final formula and avoid confusing magnetic pole strength m with magnetic moment M.
IB Physics Question 8Explain potential energy of magnetic dipole with formula and diagram wherever required.
Answer: Write the definition, draw a neat labeled diagram, define all symbols, derive the formula step-by-step if derivation is asked, and finish with physical meaning. For potential energy of magnetic dipole, the key point is to connect the diagram with the final formula and avoid confusing magnetic pole strength m with magnetic moment M.
IB Physics Question 9Explain Gauss law of magnetism with formula and diagram wherever required.
Answer: Write the definition, draw a neat labeled diagram, define all symbols, derive the formula step-by-step if derivation is asked, and finish with physical meaning. For Gauss law of magnetism, the key point is to connect the diagram with the final formula and avoid confusing magnetic pole strength m with magnetic moment M.
IB Physics Question 10Explain broken magnet concept with formula and diagram wherever required.
Answer: Write the definition, draw a neat labeled diagram, define all symbols, derive the formula step-by-step if derivation is asked, and finish with physical meaning. For broken magnet concept, the key point is to connect the diagram with the final formula and avoid confusing magnetic pole strength m with magnetic moment M.
IB Physics Question 11Explain properties of magnetic field lines with formula and diagram wherever required.
Answer: Write the definition, draw a neat labeled diagram, define all symbols, derive the formula step-by-step if derivation is asked, and finish with physical meaning. For properties of magnetic field lines, the key point is to connect the diagram with the final formula and avoid confusing magnetic pole strength m with magnetic moment M.
IB Physics Question 12Explain bar magnet as an equivalent solenoid with formula and diagram wherever required.
Answer: Write the definition, draw a neat labeled diagram, define all symbols, derive the formula step-by-step if derivation is asked, and finish with physical meaning. For bar magnet as an equivalent solenoid, the key point is to connect the diagram with the final formula and avoid confusing magnetic pole strength m with magnetic moment M.
IB Physics Question 13Explain magnetic moment and pole strength with formula and diagram wherever required.
Answer: Write the definition, draw a neat labeled diagram, define all symbols, derive the formula step-by-step if derivation is asked, and finish with physical meaning. For magnetic moment and pole strength, the key point is to connect the diagram with the final formula and avoid confusing magnetic pole strength m with magnetic moment M.
IB Physics Question 14Explain Coulomb law in magnetism with formula and diagram wherever required.
Answer: Write the definition, draw a neat labeled diagram, define all symbols, derive the formula step-by-step if derivation is asked, and finish with physical meaning. For Coulomb law in magnetism, the key point is to connect the diagram with the final formula and avoid confusing magnetic pole strength m with magnetic moment M.
IB Physics Question 15Explain axial field due to a bar magnet with formula and diagram wherever required.
Answer: Write the definition, draw a neat labeled diagram, define all symbols, derive the formula step-by-step if derivation is asked, and finish with physical meaning. For axial field due to a bar magnet, the key point is to connect the diagram with the final formula and avoid confusing magnetic pole strength m with magnetic moment M.
IB Physics Question 16Explain equatorial field due to a bar magnet with formula and diagram wherever required.
Answer: Write the definition, draw a neat labeled diagram, define all symbols, derive the formula step-by-step if derivation is asked, and finish with physical meaning. For equatorial field due to a bar magnet, the key point is to connect the diagram with the final formula and avoid confusing magnetic pole strength m with magnetic moment M.
IB Physics Question 17Explain torque on magnetic dipole with formula and diagram wherever required.
Answer: Write the definition, draw a neat labeled diagram, define all symbols, derive the formula step-by-step if derivation is asked, and finish with physical meaning. For torque on magnetic dipole, the key point is to connect the diagram with the final formula and avoid confusing magnetic pole strength m with magnetic moment M.
IB Physics Question 18Explain potential energy of magnetic dipole with formula and diagram wherever required.
Answer: Write the definition, draw a neat labeled diagram, define all symbols, derive the formula step-by-step if derivation is asked, and finish with physical meaning. For potential energy of magnetic dipole, the key point is to connect the diagram with the final formula and avoid confusing magnetic pole strength m with magnetic moment M.
IB Physics Question 19Explain Gauss law of magnetism with formula and diagram wherever required.
Answer: Write the definition, draw a neat labeled diagram, define all symbols, derive the formula step-by-step if derivation is asked, and finish with physical meaning. For Gauss law of magnetism, the key point is to connect the diagram with the final formula and avoid confusing magnetic pole strength m with magnetic moment M.
IB Physics Question 20Explain broken magnet concept with formula and diagram wherever required.
Answer: Write the definition, draw a neat labeled diagram, define all symbols, derive the formula step-by-step if derivation is asked, and finish with physical meaning. For broken magnet concept, the key point is to connect the diagram with the final formula and avoid confusing magnetic pole strength m with magnetic moment M.
IB Physics Question 21Explain properties of magnetic field lines with formula and diagram wherever required.
Answer: Write the definition, draw a neat labeled diagram, define all symbols, derive the formula step-by-step if derivation is asked, and finish with physical meaning. For properties of magnetic field lines, the key point is to connect the diagram with the final formula and avoid confusing magnetic pole strength m with magnetic moment M.
IB Physics Question 22Explain bar magnet as an equivalent solenoid with formula and diagram wherever required.
Answer: Write the definition, draw a neat labeled diagram, define all symbols, derive the formula step-by-step if derivation is asked, and finish with physical meaning. For bar magnet as an equivalent solenoid, the key point is to connect the diagram with the final formula and avoid confusing magnetic pole strength m with magnetic moment M.
IB Physics Question 23Explain magnetic moment and pole strength with formula and diagram wherever required.
Answer: Write the definition, draw a neat labeled diagram, define all symbols, derive the formula step-by-step if derivation is asked, and finish with physical meaning. For magnetic moment and pole strength, the key point is to connect the diagram with the final formula and avoid confusing magnetic pole strength m with magnetic moment M.
IB Physics Question 24Explain Coulomb law in magnetism with formula and diagram wherever required.
Answer: Write the definition, draw a neat labeled diagram, define all symbols, derive the formula step-by-step if derivation is asked, and finish with physical meaning. For Coulomb law in magnetism, the key point is to connect the diagram with the final formula and avoid confusing magnetic pole strength m with magnetic moment M.
IB Physics Question 25Explain axial field due to a bar magnet with formula and diagram wherever required.
Answer: Write the definition, draw a neat labeled diagram, define all symbols, derive the formula step-by-step if derivation is asked, and finish with physical meaning. For axial field due to a bar magnet, the key point is to connect the diagram with the final formula and avoid confusing magnetic pole strength m with magnetic moment M.
IB Physics Question 26Explain equatorial field due to a bar magnet with formula and diagram wherever required.
Answer: Write the definition, draw a neat labeled diagram, define all symbols, derive the formula step-by-step if derivation is asked, and finish with physical meaning. For equatorial field due to a bar magnet, the key point is to connect the diagram with the final formula and avoid confusing magnetic pole strength m with magnetic moment M.
IB Physics Question 27Explain torque on magnetic dipole with formula and diagram wherever required.
Answer: Write the definition, draw a neat labeled diagram, define all symbols, derive the formula step-by-step if derivation is asked, and finish with physical meaning. For torque on magnetic dipole, the key point is to connect the diagram with the final formula and avoid confusing magnetic pole strength m with magnetic moment M.
IB Physics Question 28Explain potential energy of magnetic dipole with formula and diagram wherever required.
Answer: Write the definition, draw a neat labeled diagram, define all symbols, derive the formula step-by-step if derivation is asked, and finish with physical meaning. For potential energy of magnetic dipole, the key point is to connect the diagram with the final formula and avoid confusing magnetic pole strength m with magnetic moment M.
IB Physics Question 29Explain Gauss law of magnetism with formula and diagram wherever required.
Answer: Write the definition, draw a neat labeled diagram, define all symbols, derive the formula step-by-step if derivation is asked, and finish with physical meaning. For Gauss law of magnetism, the key point is to connect the diagram with the final formula and avoid confusing magnetic pole strength m with magnetic moment M.
IB Physics Question 30Explain broken magnet concept with formula and diagram wherever required.
Answer: Write the definition, draw a neat labeled diagram, define all symbols, derive the formula step-by-step if derivation is asked, and finish with physical meaning. For broken magnet concept, the key point is to connect the diagram with the final formula and avoid confusing magnetic pole strength m with magnetic moment M.
F. ICSE Physics Questions
ICSE Physics Question 1Explain properties of magnetic field lines with formula and diagram wherever required.
Answer: Write the definition, draw a neat labeled diagram, define all symbols, derive the formula step-by-step if derivation is asked, and finish with physical meaning. For properties of magnetic field lines, the key point is to connect the diagram with the final formula and avoid confusing magnetic pole strength m with magnetic moment M.
ICSE Physics Question 2Explain bar magnet as an equivalent solenoid with formula and diagram wherever required.
Answer: Write the definition, draw a neat labeled diagram, define all symbols, derive the formula step-by-step if derivation is asked, and finish with physical meaning. For bar magnet as an equivalent solenoid, the key point is to connect the diagram with the final formula and avoid confusing magnetic pole strength m with magnetic moment M.
ICSE Physics Question 3Explain magnetic moment and pole strength with formula and diagram wherever required.
Answer: Write the definition, draw a neat labeled diagram, define all symbols, derive the formula step-by-step if derivation is asked, and finish with physical meaning. For magnetic moment and pole strength, the key point is to connect the diagram with the final formula and avoid confusing magnetic pole strength m with magnetic moment M.
ICSE Physics Question 4Explain Coulomb law in magnetism with formula and diagram wherever required.
Answer: Write the definition, draw a neat labeled diagram, define all symbols, derive the formula step-by-step if derivation is asked, and finish with physical meaning. For Coulomb law in magnetism, the key point is to connect the diagram with the final formula and avoid confusing magnetic pole strength m with magnetic moment M.
ICSE Physics Question 5Explain axial field due to a bar magnet with formula and diagram wherever required.
Answer: Write the definition, draw a neat labeled diagram, define all symbols, derive the formula step-by-step if derivation is asked, and finish with physical meaning. For axial field due to a bar magnet, the key point is to connect the diagram with the final formula and avoid confusing magnetic pole strength m with magnetic moment M.
ICSE Physics Question 6Explain equatorial field due to a bar magnet with formula and diagram wherever required.
Answer: Write the definition, draw a neat labeled diagram, define all symbols, derive the formula step-by-step if derivation is asked, and finish with physical meaning. For equatorial field due to a bar magnet, the key point is to connect the diagram with the final formula and avoid confusing magnetic pole strength m with magnetic moment M.
ICSE Physics Question 7Explain torque on magnetic dipole with formula and diagram wherever required.
Answer: Write the definition, draw a neat labeled diagram, define all symbols, derive the formula step-by-step if derivation is asked, and finish with physical meaning. For torque on magnetic dipole, the key point is to connect the diagram with the final formula and avoid confusing magnetic pole strength m with magnetic moment M.
ICSE Physics Question 8Explain potential energy of magnetic dipole with formula and diagram wherever required.
Answer: Write the definition, draw a neat labeled diagram, define all symbols, derive the formula step-by-step if derivation is asked, and finish with physical meaning. For potential energy of magnetic dipole, the key point is to connect the diagram with the final formula and avoid confusing magnetic pole strength m with magnetic moment M.
ICSE Physics Question 9Explain Gauss law of magnetism with formula and diagram wherever required.
Answer: Write the definition, draw a neat labeled diagram, define all symbols, derive the formula step-by-step if derivation is asked, and finish with physical meaning. For Gauss law of magnetism, the key point is to connect the diagram with the final formula and avoid confusing magnetic pole strength m with magnetic moment M.
ICSE Physics Question 10Explain broken magnet concept with formula and diagram wherever required.
Answer: Write the definition, draw a neat labeled diagram, define all symbols, derive the formula step-by-step if derivation is asked, and finish with physical meaning. For broken magnet concept, the key point is to connect the diagram with the final formula and avoid confusing magnetic pole strength m with magnetic moment M.
ICSE Physics Question 11Explain properties of magnetic field lines with formula and diagram wherever required.
Answer: Write the definition, draw a neat labeled diagram, define all symbols, derive the formula step-by-step if derivation is asked, and finish with physical meaning. For properties of magnetic field lines, the key point is to connect the diagram with the final formula and avoid confusing magnetic pole strength m with magnetic moment M.
ICSE Physics Question 12Explain bar magnet as an equivalent solenoid with formula and diagram wherever required.
Answer: Write the definition, draw a neat labeled diagram, define all symbols, derive the formula step-by-step if derivation is asked, and finish with physical meaning. For bar magnet as an equivalent solenoid, the key point is to connect the diagram with the final formula and avoid confusing magnetic pole strength m with magnetic moment M.
ICSE Physics Question 13Explain magnetic moment and pole strength with formula and diagram wherever required.
Answer: Write the definition, draw a neat labeled diagram, define all symbols, derive the formula step-by-step if derivation is asked, and finish with physical meaning. For magnetic moment and pole strength, the key point is to connect the diagram with the final formula and avoid confusing magnetic pole strength m with magnetic moment M.
ICSE Physics Question 14Explain Coulomb law in magnetism with formula and diagram wherever required.
Answer: Write the definition, draw a neat labeled diagram, define all symbols, derive the formula step-by-step if derivation is asked, and finish with physical meaning. For Coulomb law in magnetism, the key point is to connect the diagram with the final formula and avoid confusing magnetic pole strength m with magnetic moment M.
ICSE Physics Question 15Explain axial field due to a bar magnet with formula and diagram wherever required.
Answer: Write the definition, draw a neat labeled diagram, define all symbols, derive the formula step-by-step if derivation is asked, and finish with physical meaning. For axial field due to a bar magnet, the key point is to connect the diagram with the final formula and avoid confusing magnetic pole strength m with magnetic moment M.
ICSE Physics Question 16Explain equatorial field due to a bar magnet with formula and diagram wherever required.
Answer: Write the definition, draw a neat labeled diagram, define all symbols, derive the formula step-by-step if derivation is asked, and finish with physical meaning. For equatorial field due to a bar magnet, the key point is to connect the diagram with the final formula and avoid confusing magnetic pole strength m with magnetic moment M.
ICSE Physics Question 17Explain torque on magnetic dipole with formula and diagram wherever required.
Answer: Write the definition, draw a neat labeled diagram, define all symbols, derive the formula step-by-step if derivation is asked, and finish with physical meaning. For torque on magnetic dipole, the key point is to connect the diagram with the final formula and avoid confusing magnetic pole strength m with magnetic moment M.
ICSE Physics Question 18Explain potential energy of magnetic dipole with formula and diagram wherever required.
Answer: Write the definition, draw a neat labeled diagram, define all symbols, derive the formula step-by-step if derivation is asked, and finish with physical meaning. For potential energy of magnetic dipole, the key point is to connect the diagram with the final formula and avoid confusing magnetic pole strength m with magnetic moment M.
ICSE Physics Question 19Explain Gauss law of magnetism with formula and diagram wherever required.
Answer: Write the definition, draw a neat labeled diagram, define all symbols, derive the formula step-by-step if derivation is asked, and finish with physical meaning. For Gauss law of magnetism, the key point is to connect the diagram with the final formula and avoid confusing magnetic pole strength m with magnetic moment M.
ICSE Physics Question 20Explain broken magnet concept with formula and diagram wherever required.
Answer: Write the definition, draw a neat labeled diagram, define all symbols, derive the formula step-by-step if derivation is asked, and finish with physical meaning. For broken magnet concept, the key point is to connect the diagram with the final formula and avoid confusing magnetic pole strength m with magnetic moment M.
ICSE Physics Question 21Explain properties of magnetic field lines with formula and diagram wherever required.
Answer: Write the definition, draw a neat labeled diagram, define all symbols, derive the formula step-by-step if derivation is asked, and finish with physical meaning. For properties of magnetic field lines, the key point is to connect the diagram with the final formula and avoid confusing magnetic pole strength m with magnetic moment M.
ICSE Physics Question 22Explain bar magnet as an equivalent solenoid with formula and diagram wherever required.
Answer: Write the definition, draw a neat labeled diagram, define all symbols, derive the formula step-by-step if derivation is asked, and finish with physical meaning. For bar magnet as an equivalent solenoid, the key point is to connect the diagram with the final formula and avoid confusing magnetic pole strength m with magnetic moment M.
ICSE Physics Question 23Explain magnetic moment and pole strength with formula and diagram wherever required.
Answer: Write the definition, draw a neat labeled diagram, define all symbols, derive the formula step-by-step if derivation is asked, and finish with physical meaning. For magnetic moment and pole strength, the key point is to connect the diagram with the final formula and avoid confusing magnetic pole strength m with magnetic moment M.
ICSE Physics Question 24Explain Coulomb law in magnetism with formula and diagram wherever required.
Answer: Write the definition, draw a neat labeled diagram, define all symbols, derive the formula step-by-step if derivation is asked, and finish with physical meaning. For Coulomb law in magnetism, the key point is to connect the diagram with the final formula and avoid confusing magnetic pole strength m with magnetic moment M.
ICSE Physics Question 25Explain axial field due to a bar magnet with formula and diagram wherever required.
Answer: Write the definition, draw a neat labeled diagram, define all symbols, derive the formula step-by-step if derivation is asked, and finish with physical meaning. For axial field due to a bar magnet, the key point is to connect the diagram with the final formula and avoid confusing magnetic pole strength m with magnetic moment M.
ICSE Physics Question 26Explain equatorial field due to a bar magnet with formula and diagram wherever required.
Answer: Write the definition, draw a neat labeled diagram, define all symbols, derive the formula step-by-step if derivation is asked, and finish with physical meaning. For equatorial field due to a bar magnet, the key point is to connect the diagram with the final formula and avoid confusing magnetic pole strength m with magnetic moment M.
ICSE Physics Question 27Explain torque on magnetic dipole with formula and diagram wherever required.
Answer: Write the definition, draw a neat labeled diagram, define all symbols, derive the formula step-by-step if derivation is asked, and finish with physical meaning. For torque on magnetic dipole, the key point is to connect the diagram with the final formula and avoid confusing magnetic pole strength m with magnetic moment M.
ICSE Physics Question 28Explain potential energy of magnetic dipole with formula and diagram wherever required.
Answer: Write the definition, draw a neat labeled diagram, define all symbols, derive the formula step-by-step if derivation is asked, and finish with physical meaning. For potential energy of magnetic dipole, the key point is to connect the diagram with the final formula and avoid confusing magnetic pole strength m with magnetic moment M.
ICSE Physics Question 29Explain Gauss law of magnetism with formula and diagram wherever required.
Answer: Write the definition, draw a neat labeled diagram, define all symbols, derive the formula step-by-step if derivation is asked, and finish with physical meaning. For Gauss law of magnetism, the key point is to connect the diagram with the final formula and avoid confusing magnetic pole strength m with magnetic moment M.
ICSE Physics Question 30Explain broken magnet concept with formula and diagram wherever required.
Answer: Write the definition, draw a neat labeled diagram, define all symbols, derive the formula step-by-step if derivation is asked, and finish with physical meaning. For broken magnet concept, the key point is to connect the diagram with the final formula and avoid confusing magnetic pole strength m with magnetic moment M.
G. IGCSE Physics Questions
IGCSE Physics Question 1Explain properties of magnetic field lines with formula and diagram wherever required.
Answer: Write the definition, draw a neat labeled diagram, define all symbols, derive the formula step-by-step if derivation is asked, and finish with physical meaning. For properties of magnetic field lines, the key point is to connect the diagram with the final formula and avoid confusing magnetic pole strength m with magnetic moment M.
IGCSE Physics Question 2Explain bar magnet as an equivalent solenoid with formula and diagram wherever required.
Answer: Write the definition, draw a neat labeled diagram, define all symbols, derive the formula step-by-step if derivation is asked, and finish with physical meaning. For bar magnet as an equivalent solenoid, the key point is to connect the diagram with the final formula and avoid confusing magnetic pole strength m with magnetic moment M.
IGCSE Physics Question 3Explain magnetic moment and pole strength with formula and diagram wherever required.
Answer: Write the definition, draw a neat labeled diagram, define all symbols, derive the formula step-by-step if derivation is asked, and finish with physical meaning. For magnetic moment and pole strength, the key point is to connect the diagram with the final formula and avoid confusing magnetic pole strength m with magnetic moment M.
IGCSE Physics Question 4Explain Coulomb law in magnetism with formula and diagram wherever required.
Answer: Write the definition, draw a neat labeled diagram, define all symbols, derive the formula step-by-step if derivation is asked, and finish with physical meaning. For Coulomb law in magnetism, the key point is to connect the diagram with the final formula and avoid confusing magnetic pole strength m with magnetic moment M.
IGCSE Physics Question 5Explain axial field due to a bar magnet with formula and diagram wherever required.
Answer: Write the definition, draw a neat labeled diagram, define all symbols, derive the formula step-by-step if derivation is asked, and finish with physical meaning. For axial field due to a bar magnet, the key point is to connect the diagram with the final formula and avoid confusing magnetic pole strength m with magnetic moment M.
IGCSE Physics Question 6Explain equatorial field due to a bar magnet with formula and diagram wherever required.
Answer: Write the definition, draw a neat labeled diagram, define all symbols, derive the formula step-by-step if derivation is asked, and finish with physical meaning. For equatorial field due to a bar magnet, the key point is to connect the diagram with the final formula and avoid confusing magnetic pole strength m with magnetic moment M.
IGCSE Physics Question 7Explain torque on magnetic dipole with formula and diagram wherever required.
Answer: Write the definition, draw a neat labeled diagram, define all symbols, derive the formula step-by-step if derivation is asked, and finish with physical meaning. For torque on magnetic dipole, the key point is to connect the diagram with the final formula and avoid confusing magnetic pole strength m with magnetic moment M.
IGCSE Physics Question 8Explain potential energy of magnetic dipole with formula and diagram wherever required.
Answer: Write the definition, draw a neat labeled diagram, define all symbols, derive the formula step-by-step if derivation is asked, and finish with physical meaning. For potential energy of magnetic dipole, the key point is to connect the diagram with the final formula and avoid confusing magnetic pole strength m with magnetic moment M.
IGCSE Physics Question 9Explain Gauss law of magnetism with formula and diagram wherever required.
Answer: Write the definition, draw a neat labeled diagram, define all symbols, derive the formula step-by-step if derivation is asked, and finish with physical meaning. For Gauss law of magnetism, the key point is to connect the diagram with the final formula and avoid confusing magnetic pole strength m with magnetic moment M.
IGCSE Physics Question 10Explain broken magnet concept with formula and diagram wherever required.
Answer: Write the definition, draw a neat labeled diagram, define all symbols, derive the formula step-by-step if derivation is asked, and finish with physical meaning. For broken magnet concept, the key point is to connect the diagram with the final formula and avoid confusing magnetic pole strength m with magnetic moment M.
IGCSE Physics Question 11Explain properties of magnetic field lines with formula and diagram wherever required.
Answer: Write the definition, draw a neat labeled diagram, define all symbols, derive the formula step-by-step if derivation is asked, and finish with physical meaning. For properties of magnetic field lines, the key point is to connect the diagram with the final formula and avoid confusing magnetic pole strength m with magnetic moment M.
IGCSE Physics Question 12Explain bar magnet as an equivalent solenoid with formula and diagram wherever required.
Answer: Write the definition, draw a neat labeled diagram, define all symbols, derive the formula step-by-step if derivation is asked, and finish with physical meaning. For bar magnet as an equivalent solenoid, the key point is to connect the diagram with the final formula and avoid confusing magnetic pole strength m with magnetic moment M.
IGCSE Physics Question 13Explain magnetic moment and pole strength with formula and diagram wherever required.
Answer: Write the definition, draw a neat labeled diagram, define all symbols, derive the formula step-by-step if derivation is asked, and finish with physical meaning. For magnetic moment and pole strength, the key point is to connect the diagram with the final formula and avoid confusing magnetic pole strength m with magnetic moment M.
IGCSE Physics Question 14Explain Coulomb law in magnetism with formula and diagram wherever required.
Answer: Write the definition, draw a neat labeled diagram, define all symbols, derive the formula step-by-step if derivation is asked, and finish with physical meaning. For Coulomb law in magnetism, the key point is to connect the diagram with the final formula and avoid confusing magnetic pole strength m with magnetic moment M.
IGCSE Physics Question 15Explain axial field due to a bar magnet with formula and diagram wherever required.
Answer: Write the definition, draw a neat labeled diagram, define all symbols, derive the formula step-by-step if derivation is asked, and finish with physical meaning. For axial field due to a bar magnet, the key point is to connect the diagram with the final formula and avoid confusing magnetic pole strength m with magnetic moment M.
IGCSE Physics Question 16Explain equatorial field due to a bar magnet with formula and diagram wherever required.
Answer: Write the definition, draw a neat labeled diagram, define all symbols, derive the formula step-by-step if derivation is asked, and finish with physical meaning. For equatorial field due to a bar magnet, the key point is to connect the diagram with the final formula and avoid confusing magnetic pole strength m with magnetic moment M.
IGCSE Physics Question 17Explain torque on magnetic dipole with formula and diagram wherever required.
Answer: Write the definition, draw a neat labeled diagram, define all symbols, derive the formula step-by-step if derivation is asked, and finish with physical meaning. For torque on magnetic dipole, the key point is to connect the diagram with the final formula and avoid confusing magnetic pole strength m with magnetic moment M.
IGCSE Physics Question 18Explain potential energy of magnetic dipole with formula and diagram wherever required.
Answer: Write the definition, draw a neat labeled diagram, define all symbols, derive the formula step-by-step if derivation is asked, and finish with physical meaning. For potential energy of magnetic dipole, the key point is to connect the diagram with the final formula and avoid confusing magnetic pole strength m with magnetic moment M.
IGCSE Physics Question 19Explain Gauss law of magnetism with formula and diagram wherever required.
Answer: Write the definition, draw a neat labeled diagram, define all symbols, derive the formula step-by-step if derivation is asked, and finish with physical meaning. For Gauss law of magnetism, the key point is to connect the diagram with the final formula and avoid confusing magnetic pole strength m with magnetic moment M.
IGCSE Physics Question 20Explain broken magnet concept with formula and diagram wherever required.
Answer: Write the definition, draw a neat labeled diagram, define all symbols, derive the formula step-by-step if derivation is asked, and finish with physical meaning. For broken magnet concept, the key point is to connect the diagram with the final formula and avoid confusing magnetic pole strength m with magnetic moment M.
IGCSE Physics Question 21Explain properties of magnetic field lines with formula and diagram wherever required.
Answer: Write the definition, draw a neat labeled diagram, define all symbols, derive the formula step-by-step if derivation is asked, and finish with physical meaning. For properties of magnetic field lines, the key point is to connect the diagram with the final formula and avoid confusing magnetic pole strength m with magnetic moment M.
IGCSE Physics Question 22Explain bar magnet as an equivalent solenoid with formula and diagram wherever required.
Answer: Write the definition, draw a neat labeled diagram, define all symbols, derive the formula step-by-step if derivation is asked, and finish with physical meaning. For bar magnet as an equivalent solenoid, the key point is to connect the diagram with the final formula and avoid confusing magnetic pole strength m with magnetic moment M.
IGCSE Physics Question 23Explain magnetic moment and pole strength with formula and diagram wherever required.
Answer: Write the definition, draw a neat labeled diagram, define all symbols, derive the formula step-by-step if derivation is asked, and finish with physical meaning. For magnetic moment and pole strength, the key point is to connect the diagram with the final formula and avoid confusing magnetic pole strength m with magnetic moment M.
IGCSE Physics Question 24Explain Coulomb law in magnetism with formula and diagram wherever required.
Answer: Write the definition, draw a neat labeled diagram, define all symbols, derive the formula step-by-step if derivation is asked, and finish with physical meaning. For Coulomb law in magnetism, the key point is to connect the diagram with the final formula and avoid confusing magnetic pole strength m with magnetic moment M.
IGCSE Physics Question 25Explain axial field due to a bar magnet with formula and diagram wherever required.
Answer: Write the definition, draw a neat labeled diagram, define all symbols, derive the formula step-by-step if derivation is asked, and finish with physical meaning. For axial field due to a bar magnet, the key point is to connect the diagram with the final formula and avoid confusing magnetic pole strength m with magnetic moment M.
IGCSE Physics Question 26Explain equatorial field due to a bar magnet with formula and diagram wherever required.
Answer: Write the definition, draw a neat labeled diagram, define all symbols, derive the formula step-by-step if derivation is asked, and finish with physical meaning. For equatorial field due to a bar magnet, the key point is to connect the diagram with the final formula and avoid confusing magnetic pole strength m with magnetic moment M.
IGCSE Physics Question 27Explain torque on magnetic dipole with formula and diagram wherever required.
Answer: Write the definition, draw a neat labeled diagram, define all symbols, derive the formula step-by-step if derivation is asked, and finish with physical meaning. For torque on magnetic dipole, the key point is to connect the diagram with the final formula and avoid confusing magnetic pole strength m with magnetic moment M.
IGCSE Physics Question 28Explain potential energy of magnetic dipole with formula and diagram wherever required.
Answer: Write the definition, draw a neat labeled diagram, define all symbols, derive the formula step-by-step if derivation is asked, and finish with physical meaning. For potential energy of magnetic dipole, the key point is to connect the diagram with the final formula and avoid confusing magnetic pole strength m with magnetic moment M.
IGCSE Physics Question 29Explain Gauss law of magnetism with formula and diagram wherever required.
Answer: Write the definition, draw a neat labeled diagram, define all symbols, derive the formula step-by-step if derivation is asked, and finish with physical meaning. For Gauss law of magnetism, the key point is to connect the diagram with the final formula and avoid confusing magnetic pole strength m with magnetic moment M.
IGCSE Physics Question 30Explain broken magnet concept with formula and diagram wherever required.
Answer: Write the definition, draw a neat labeled diagram, define all symbols, derive the formula step-by-step if derivation is asked, and finish with physical meaning. For broken magnet concept, the key point is to connect the diagram with the final formula and avoid confusing magnetic pole strength m with magnetic moment M.
H. British Curriculum / A-Level Physics
A-Level Physics Question 1Explain properties of magnetic field lines with formula and diagram wherever required.
Answer: Write the definition, draw a neat labeled diagram, define all symbols, derive the formula step-by-step if derivation is asked, and finish with physical meaning. For properties of magnetic field lines, the key point is to connect the diagram with the final formula and avoid confusing magnetic pole strength m with magnetic moment M.
A-Level Physics Question 2Explain bar magnet as an equivalent solenoid with formula and diagram wherever required.
Answer: Write the definition, draw a neat labeled diagram, define all symbols, derive the formula step-by-step if derivation is asked, and finish with physical meaning. For bar magnet as an equivalent solenoid, the key point is to connect the diagram with the final formula and avoid confusing magnetic pole strength m with magnetic moment M.
A-Level Physics Question 3Explain magnetic moment and pole strength with formula and diagram wherever required.
Answer: Write the definition, draw a neat labeled diagram, define all symbols, derive the formula step-by-step if derivation is asked, and finish with physical meaning. For magnetic moment and pole strength, the key point is to connect the diagram with the final formula and avoid confusing magnetic pole strength m with magnetic moment M.
A-Level Physics Question 4Explain Coulomb law in magnetism with formula and diagram wherever required.
Answer: Write the definition, draw a neat labeled diagram, define all symbols, derive the formula step-by-step if derivation is asked, and finish with physical meaning. For Coulomb law in magnetism, the key point is to connect the diagram with the final formula and avoid confusing magnetic pole strength m with magnetic moment M.
A-Level Physics Question 5Explain axial field due to a bar magnet with formula and diagram wherever required.
Answer: Write the definition, draw a neat labeled diagram, define all symbols, derive the formula step-by-step if derivation is asked, and finish with physical meaning. For axial field due to a bar magnet, the key point is to connect the diagram with the final formula and avoid confusing magnetic pole strength m with magnetic moment M.
A-Level Physics Question 6Explain equatorial field due to a bar magnet with formula and diagram wherever required.
Answer: Write the definition, draw a neat labeled diagram, define all symbols, derive the formula step-by-step if derivation is asked, and finish with physical meaning. For equatorial field due to a bar magnet, the key point is to connect the diagram with the final formula and avoid confusing magnetic pole strength m with magnetic moment M.
A-Level Physics Question 7Explain torque on magnetic dipole with formula and diagram wherever required.
Answer: Write the definition, draw a neat labeled diagram, define all symbols, derive the formula step-by-step if derivation is asked, and finish with physical meaning. For torque on magnetic dipole, the key point is to connect the diagram with the final formula and avoid confusing magnetic pole strength m with magnetic moment M.
A-Level Physics Question 8Explain potential energy of magnetic dipole with formula and diagram wherever required.
Answer: Write the definition, draw a neat labeled diagram, define all symbols, derive the formula step-by-step if derivation is asked, and finish with physical meaning. For potential energy of magnetic dipole, the key point is to connect the diagram with the final formula and avoid confusing magnetic pole strength m with magnetic moment M.
A-Level Physics Question 9Explain Gauss law of magnetism with formula and diagram wherever required.
Answer: Write the definition, draw a neat labeled diagram, define all symbols, derive the formula step-by-step if derivation is asked, and finish with physical meaning. For Gauss law of magnetism, the key point is to connect the diagram with the final formula and avoid confusing magnetic pole strength m with magnetic moment M.
A-Level Physics Question 10Explain broken magnet concept with formula and diagram wherever required.
Answer: Write the definition, draw a neat labeled diagram, define all symbols, derive the formula step-by-step if derivation is asked, and finish with physical meaning. For broken magnet concept, the key point is to connect the diagram with the final formula and avoid confusing magnetic pole strength m with magnetic moment M.
A-Level Physics Question 11Explain properties of magnetic field lines with formula and diagram wherever required.
Answer: Write the definition, draw a neat labeled diagram, define all symbols, derive the formula step-by-step if derivation is asked, and finish with physical meaning. For properties of magnetic field lines, the key point is to connect the diagram with the final formula and avoid confusing magnetic pole strength m with magnetic moment M.
A-Level Physics Question 12Explain bar magnet as an equivalent solenoid with formula and diagram wherever required.
Answer: Write the definition, draw a neat labeled diagram, define all symbols, derive the formula step-by-step if derivation is asked, and finish with physical meaning. For bar magnet as an equivalent solenoid, the key point is to connect the diagram with the final formula and avoid confusing magnetic pole strength m with magnetic moment M.
A-Level Physics Question 13Explain magnetic moment and pole strength with formula and diagram wherever required.
Answer: Write the definition, draw a neat labeled diagram, define all symbols, derive the formula step-by-step if derivation is asked, and finish with physical meaning. For magnetic moment and pole strength, the key point is to connect the diagram with the final formula and avoid confusing magnetic pole strength m with magnetic moment M.
A-Level Physics Question 14Explain Coulomb law in magnetism with formula and diagram wherever required.
Answer: Write the definition, draw a neat labeled diagram, define all symbols, derive the formula step-by-step if derivation is asked, and finish with physical meaning. For Coulomb law in magnetism, the key point is to connect the diagram with the final formula and avoid confusing magnetic pole strength m with magnetic moment M.
A-Level Physics Question 15Explain axial field due to a bar magnet with formula and diagram wherever required.
Answer: Write the definition, draw a neat labeled diagram, define all symbols, derive the formula step-by-step if derivation is asked, and finish with physical meaning. For axial field due to a bar magnet, the key point is to connect the diagram with the final formula and avoid confusing magnetic pole strength m with magnetic moment M.
A-Level Physics Question 16Explain equatorial field due to a bar magnet with formula and diagram wherever required.
Answer: Write the definition, draw a neat labeled diagram, define all symbols, derive the formula step-by-step if derivation is asked, and finish with physical meaning. For equatorial field due to a bar magnet, the key point is to connect the diagram with the final formula and avoid confusing magnetic pole strength m with magnetic moment M.
A-Level Physics Question 17Explain torque on magnetic dipole with formula and diagram wherever required.
Answer: Write the definition, draw a neat labeled diagram, define all symbols, derive the formula step-by-step if derivation is asked, and finish with physical meaning. For torque on magnetic dipole, the key point is to connect the diagram with the final formula and avoid confusing magnetic pole strength m with magnetic moment M.
A-Level Physics Question 18Explain potential energy of magnetic dipole with formula and diagram wherever required.
Answer: Write the definition, draw a neat labeled diagram, define all symbols, derive the formula step-by-step if derivation is asked, and finish with physical meaning. For potential energy of magnetic dipole, the key point is to connect the diagram with the final formula and avoid confusing magnetic pole strength m with magnetic moment M.
A-Level Physics Question 19Explain Gauss law of magnetism with formula and diagram wherever required.
Answer: Write the definition, draw a neat labeled diagram, define all symbols, derive the formula step-by-step if derivation is asked, and finish with physical meaning. For Gauss law of magnetism, the key point is to connect the diagram with the final formula and avoid confusing magnetic pole strength m with magnetic moment M.
A-Level Physics Question 20Explain broken magnet concept with formula and diagram wherever required.
Answer: Write the definition, draw a neat labeled diagram, define all symbols, derive the formula step-by-step if derivation is asked, and finish with physical meaning. For broken magnet concept, the key point is to connect the diagram with the final formula and avoid confusing magnetic pole strength m with magnetic moment M.
A-Level Physics Question 21Explain properties of magnetic field lines with formula and diagram wherever required.
Answer: Write the definition, draw a neat labeled diagram, define all symbols, derive the formula step-by-step if derivation is asked, and finish with physical meaning. For properties of magnetic field lines, the key point is to connect the diagram with the final formula and avoid confusing magnetic pole strength m with magnetic moment M.
A-Level Physics Question 22Explain bar magnet as an equivalent solenoid with formula and diagram wherever required.
Answer: Write the definition, draw a neat labeled diagram, define all symbols, derive the formula step-by-step if derivation is asked, and finish with physical meaning. For bar magnet as an equivalent solenoid, the key point is to connect the diagram with the final formula and avoid confusing magnetic pole strength m with magnetic moment M.
A-Level Physics Question 23Explain magnetic moment and pole strength with formula and diagram wherever required.
Answer: Write the definition, draw a neat labeled diagram, define all symbols, derive the formula step-by-step if derivation is asked, and finish with physical meaning. For magnetic moment and pole strength, the key point is to connect the diagram with the final formula and avoid confusing magnetic pole strength m with magnetic moment M.
A-Level Physics Question 24Explain Coulomb law in magnetism with formula and diagram wherever required.
Answer: Write the definition, draw a neat labeled diagram, define all symbols, derive the formula step-by-step if derivation is asked, and finish with physical meaning. For Coulomb law in magnetism, the key point is to connect the diagram with the final formula and avoid confusing magnetic pole strength m with magnetic moment M.
A-Level Physics Question 25Explain axial field due to a bar magnet with formula and diagram wherever required.
Answer: Write the definition, draw a neat labeled diagram, define all symbols, derive the formula step-by-step if derivation is asked, and finish with physical meaning. For axial field due to a bar magnet, the key point is to connect the diagram with the final formula and avoid confusing magnetic pole strength m with magnetic moment M.
A-Level Physics Question 26Explain equatorial field due to a bar magnet with formula and diagram wherever required.
Answer: Write the definition, draw a neat labeled diagram, define all symbols, derive the formula step-by-step if derivation is asked, and finish with physical meaning. For equatorial field due to a bar magnet, the key point is to connect the diagram with the final formula and avoid confusing magnetic pole strength m with magnetic moment M.
A-Level Physics Question 27Explain torque on magnetic dipole with formula and diagram wherever required.
Answer: Write the definition, draw a neat labeled diagram, define all symbols, derive the formula step-by-step if derivation is asked, and finish with physical meaning. For torque on magnetic dipole, the key point is to connect the diagram with the final formula and avoid confusing magnetic pole strength m with magnetic moment M.
A-Level Physics Question 28Explain potential energy of magnetic dipole with formula and diagram wherever required.
Answer: Write the definition, draw a neat labeled diagram, define all symbols, derive the formula step-by-step if derivation is asked, and finish with physical meaning. For potential energy of magnetic dipole, the key point is to connect the diagram with the final formula and avoid confusing magnetic pole strength m with magnetic moment M.
A-Level Physics Question 29Explain Gauss law of magnetism with formula and diagram wherever required.
Answer: Write the definition, draw a neat labeled diagram, define all symbols, derive the formula step-by-step if derivation is asked, and finish with physical meaning. For Gauss law of magnetism, the key point is to connect the diagram with the final formula and avoid confusing magnetic pole strength m with magnetic moment M.
A-Level Physics Question 30Explain broken magnet concept with formula and diagram wherever required.
Answer: Write the definition, draw a neat labeled diagram, define all symbols, derive the formula step-by-step if derivation is asked, and finish with physical meaning. For broken magnet concept, the key point is to connect the diagram with the final formula and avoid confusing magnetic pole strength m with magnetic moment M.
15. Case Study Section
Case Study 1Case study based on bar magnet field lines.
Scenario: A student observes bar magnet field lines in a school laboratory.
Questions: Identify the field direction, write the relevant formula, explain the physical meaning, and mention one common mistake.
Solution: Use magnetic field line rules, magnetic dipole formulas and Gauss law where required. If the case involves force balance, use F_magnetic = mg and F = (μ₀/4π)m₁m₂/r². If the case involves a dipole, use τ = MB sinθ and U = -MB cosθ.
Questions: Identify the field direction, write the relevant formula, explain the physical meaning, and mention one common mistake.
Solution: Use magnetic field line rules, magnetic dipole formulas and Gauss law where required. If the case involves force balance, use F_magnetic = mg and F = (μ₀/4π)m₁m₂/r². If the case involves a dipole, use τ = MB sinθ and U = -MB cosθ.
Case Study 2Case study based on broken magnet.
Scenario: A student observes broken magnet in a school laboratory.
Questions: Identify the field direction, write the relevant formula, explain the physical meaning, and mention one common mistake.
Solution: Use magnetic field line rules, magnetic dipole formulas and Gauss law where required. If the case involves force balance, use F_magnetic = mg and F = (μ₀/4π)m₁m₂/r². If the case involves a dipole, use τ = MB sinθ and U = -MB cosθ.
Questions: Identify the field direction, write the relevant formula, explain the physical meaning, and mention one common mistake.
Solution: Use magnetic field line rules, magnetic dipole formulas and Gauss law where required. If the case involves force balance, use F_magnetic = mg and F = (μ₀/4π)m₁m₂/r². If the case involves a dipole, use τ = MB sinθ and U = -MB cosθ.
Case Study 3Case study based on compass needle.
Scenario: A student observes compass needle in a school laboratory.
Questions: Identify the field direction, write the relevant formula, explain the physical meaning, and mention one common mistake.
Solution: Use magnetic field line rules, magnetic dipole formulas and Gauss law where required. If the case involves force balance, use F_magnetic = mg and F = (μ₀/4π)m₁m₂/r². If the case involves a dipole, use τ = MB sinθ and U = -MB cosθ.
Questions: Identify the field direction, write the relevant formula, explain the physical meaning, and mention one common mistake.
Solution: Use magnetic field line rules, magnetic dipole formulas and Gauss law where required. If the case involves force balance, use F_magnetic = mg and F = (μ₀/4π)m₁m₂/r². If the case involves a dipole, use τ = MB sinθ and U = -MB cosθ.
Case Study 4Case study based on axial and equatorial fields.
Scenario: A student observes axial and equatorial fields in a school laboratory.
Questions: Identify the field direction, write the relevant formula, explain the physical meaning, and mention one common mistake.
Solution: Use magnetic field line rules, magnetic dipole formulas and Gauss law where required. If the case involves force balance, use F_magnetic = mg and F = (μ₀/4π)m₁m₂/r². If the case involves a dipole, use τ = MB sinθ and U = -MB cosθ.
Questions: Identify the field direction, write the relevant formula, explain the physical meaning, and mention one common mistake.
Solution: Use magnetic field line rules, magnetic dipole formulas and Gauss law where required. If the case involves force balance, use F_magnetic = mg and F = (μ₀/4π)m₁m₂/r². If the case involves a dipole, use τ = MB sinθ and U = -MB cosθ.
Case Study 5Case study based on magnetic dipole in uniform field.
Scenario: A student observes magnetic dipole in uniform field in a school laboratory.
Questions: Identify the field direction, write the relevant formula, explain the physical meaning, and mention one common mistake.
Solution: Use magnetic field line rules, magnetic dipole formulas and Gauss law where required. If the case involves force balance, use F_magnetic = mg and F = (μ₀/4π)m₁m₂/r². If the case involves a dipole, use τ = MB sinθ and U = -MB cosθ.
Questions: Identify the field direction, write the relevant formula, explain the physical meaning, and mention one common mistake.
Solution: Use magnetic field line rules, magnetic dipole formulas and Gauss law where required. If the case involves force balance, use F_magnetic = mg and F = (μ₀/4π)m₁m₂/r². If the case involves a dipole, use τ = MB sinθ and U = -MB cosθ.
Case Study 6Case study based on horseshoe magnet.
Scenario: A student observes horseshoe magnet in a school laboratory.
Questions: Identify the field direction, write the relevant formula, explain the physical meaning, and mention one common mistake.
Solution: Use magnetic field line rules, magnetic dipole formulas and Gauss law where required. If the case involves force balance, use F_magnetic = mg and F = (μ₀/4π)m₁m₂/r². If the case involves a dipole, use τ = MB sinθ and U = -MB cosθ.
Questions: Identify the field direction, write the relevant formula, explain the physical meaning, and mention one common mistake.
Solution: Use magnetic field line rules, magnetic dipole formulas and Gauss law where required. If the case involves force balance, use F_magnetic = mg and F = (μ₀/4π)m₁m₂/r². If the case involves a dipole, use τ = MB sinθ and U = -MB cosθ.
Case Study 7Case study based on Gauss law of magnetism.
Scenario: A student observes Gauss law of magnetism in a school laboratory.
Questions: Identify the field direction, write the relevant formula, explain the physical meaning, and mention one common mistake.
Solution: Use magnetic field line rules, magnetic dipole formulas and Gauss law where required. If the case involves force balance, use F_magnetic = mg and F = (μ₀/4π)m₁m₂/r². If the case involves a dipole, use τ = MB sinθ and U = -MB cosθ.
Questions: Identify the field direction, write the relevant formula, explain the physical meaning, and mention one common mistake.
Solution: Use magnetic field line rules, magnetic dipole formulas and Gauss law where required. If the case involves force balance, use F_magnetic = mg and F = (μ₀/4π)m₁m₂/r². If the case involves a dipole, use τ = MB sinθ and U = -MB cosθ.
Case Study 8Case study based on magnet falling through conducting coil.
Scenario: A student observes magnet falling through conducting coil in a school laboratory.
Questions: Identify the field direction, write the relevant formula, explain the physical meaning, and mention one common mistake.
Solution: Use magnetic field line rules, magnetic dipole formulas and Gauss law where required. If the case involves force balance, use F_magnetic = mg and F = (μ₀/4π)m₁m₂/r². If the case involves a dipole, use τ = MB sinθ and U = -MB cosθ.
Questions: Identify the field direction, write the relevant formula, explain the physical meaning, and mention one common mistake.
Solution: Use magnetic field line rules, magnetic dipole formulas and Gauss law where required. If the case involves force balance, use F_magnetic = mg and F = (μ₀/4π)m₁m₂/r². If the case involves a dipole, use τ = MB sinθ and U = -MB cosθ.
Case Study 9Case study based on magnetic force balancing weight.
Scenario: A student observes magnetic force balancing weight in a school laboratory.
Questions: Identify the field direction, write the relevant formula, explain the physical meaning, and mention one common mistake.
Solution: Use magnetic field line rules, magnetic dipole formulas and Gauss law where required. If the case involves force balance, use F_magnetic = mg and F = (μ₀/4π)m₁m₂/r². If the case involves a dipole, use τ = MB sinθ and U = -MB cosθ.
Questions: Identify the field direction, write the relevant formula, explain the physical meaning, and mention one common mistake.
Solution: Use magnetic field line rules, magnetic dipole formulas and Gauss law where required. If the case involves force balance, use F_magnetic = mg and F = (μ₀/4π)m₁m₂/r². If the case involves a dipole, use τ = MB sinθ and U = -MB cosθ.
Case Study 10Case study based on bar magnet field lines.
Scenario: A student observes bar magnet field lines in a school laboratory.
Questions: Identify the field direction, write the relevant formula, explain the physical meaning, and mention one common mistake.
Solution: Use magnetic field line rules, magnetic dipole formulas and Gauss law where required. If the case involves force balance, use F_magnetic = mg and F = (μ₀/4π)m₁m₂/r². If the case involves a dipole, use τ = MB sinθ and U = -MB cosθ.
Questions: Identify the field direction, write the relevant formula, explain the physical meaning, and mention one common mistake.
Solution: Use magnetic field line rules, magnetic dipole formulas and Gauss law where required. If the case involves force balance, use F_magnetic = mg and F = (μ₀/4π)m₁m₂/r². If the case involves a dipole, use τ = MB sinθ and U = -MB cosθ.
Case Study 11Case study based on broken magnet.
Scenario: A student observes broken magnet in a school laboratory.
Questions: Identify the field direction, write the relevant formula, explain the physical meaning, and mention one common mistake.
Solution: Use magnetic field line rules, magnetic dipole formulas and Gauss law where required. If the case involves force balance, use F_magnetic = mg and F = (μ₀/4π)m₁m₂/r². If the case involves a dipole, use τ = MB sinθ and U = -MB cosθ.
Questions: Identify the field direction, write the relevant formula, explain the physical meaning, and mention one common mistake.
Solution: Use magnetic field line rules, magnetic dipole formulas and Gauss law where required. If the case involves force balance, use F_magnetic = mg and F = (μ₀/4π)m₁m₂/r². If the case involves a dipole, use τ = MB sinθ and U = -MB cosθ.
Case Study 12Case study based on compass needle.
Scenario: A student observes compass needle in a school laboratory.
Questions: Identify the field direction, write the relevant formula, explain the physical meaning, and mention one common mistake.
Solution: Use magnetic field line rules, magnetic dipole formulas and Gauss law where required. If the case involves force balance, use F_magnetic = mg and F = (μ₀/4π)m₁m₂/r². If the case involves a dipole, use τ = MB sinθ and U = -MB cosθ.
Questions: Identify the field direction, write the relevant formula, explain the physical meaning, and mention one common mistake.
Solution: Use magnetic field line rules, magnetic dipole formulas and Gauss law where required. If the case involves force balance, use F_magnetic = mg and F = (μ₀/4π)m₁m₂/r². If the case involves a dipole, use τ = MB sinθ and U = -MB cosθ.
Case Study 13Case study based on axial and equatorial fields.
Scenario: A student observes axial and equatorial fields in a school laboratory.
Questions: Identify the field direction, write the relevant formula, explain the physical meaning, and mention one common mistake.
Solution: Use magnetic field line rules, magnetic dipole formulas and Gauss law where required. If the case involves force balance, use F_magnetic = mg and F = (μ₀/4π)m₁m₂/r². If the case involves a dipole, use τ = MB sinθ and U = -MB cosθ.
Questions: Identify the field direction, write the relevant formula, explain the physical meaning, and mention one common mistake.
Solution: Use magnetic field line rules, magnetic dipole formulas and Gauss law where required. If the case involves force balance, use F_magnetic = mg and F = (μ₀/4π)m₁m₂/r². If the case involves a dipole, use τ = MB sinθ and U = -MB cosθ.
Case Study 14Case study based on magnetic dipole in uniform field.
Scenario: A student observes magnetic dipole in uniform field in a school laboratory.
Questions: Identify the field direction, write the relevant formula, explain the physical meaning, and mention one common mistake.
Solution: Use magnetic field line rules, magnetic dipole formulas and Gauss law where required. If the case involves force balance, use F_magnetic = mg and F = (μ₀/4π)m₁m₂/r². If the case involves a dipole, use τ = MB sinθ and U = -MB cosθ.
Questions: Identify the field direction, write the relevant formula, explain the physical meaning, and mention one common mistake.
Solution: Use magnetic field line rules, magnetic dipole formulas and Gauss law where required. If the case involves force balance, use F_magnetic = mg and F = (μ₀/4π)m₁m₂/r². If the case involves a dipole, use τ = MB sinθ and U = -MB cosθ.
Case Study 15Case study based on horseshoe magnet.
Scenario: A student observes horseshoe magnet in a school laboratory.
Questions: Identify the field direction, write the relevant formula, explain the physical meaning, and mention one common mistake.
Solution: Use magnetic field line rules, magnetic dipole formulas and Gauss law where required. If the case involves force balance, use F_magnetic = mg and F = (μ₀/4π)m₁m₂/r². If the case involves a dipole, use τ = MB sinθ and U = -MB cosθ.
Questions: Identify the field direction, write the relevant formula, explain the physical meaning, and mention one common mistake.
Solution: Use magnetic field line rules, magnetic dipole formulas and Gauss law where required. If the case involves force balance, use F_magnetic = mg and F = (μ₀/4π)m₁m₂/r². If the case involves a dipole, use τ = MB sinθ and U = -MB cosθ.
Case Study 16Case study based on Gauss law of magnetism.
Scenario: A student observes Gauss law of magnetism in a school laboratory.
Questions: Identify the field direction, write the relevant formula, explain the physical meaning, and mention one common mistake.
Solution: Use magnetic field line rules, magnetic dipole formulas and Gauss law where required. If the case involves force balance, use F_magnetic = mg and F = (μ₀/4π)m₁m₂/r². If the case involves a dipole, use τ = MB sinθ and U = -MB cosθ.
Questions: Identify the field direction, write the relevant formula, explain the physical meaning, and mention one common mistake.
Solution: Use magnetic field line rules, magnetic dipole formulas and Gauss law where required. If the case involves force balance, use F_magnetic = mg and F = (μ₀/4π)m₁m₂/r². If the case involves a dipole, use τ = MB sinθ and U = -MB cosθ.
Case Study 17Case study based on magnet falling through conducting coil.
Scenario: A student observes magnet falling through conducting coil in a school laboratory.
Questions: Identify the field direction, write the relevant formula, explain the physical meaning, and mention one common mistake.
Solution: Use magnetic field line rules, magnetic dipole formulas and Gauss law where required. If the case involves force balance, use F_magnetic = mg and F = (μ₀/4π)m₁m₂/r². If the case involves a dipole, use τ = MB sinθ and U = -MB cosθ.
Questions: Identify the field direction, write the relevant formula, explain the physical meaning, and mention one common mistake.
Solution: Use magnetic field line rules, magnetic dipole formulas and Gauss law where required. If the case involves force balance, use F_magnetic = mg and F = (μ₀/4π)m₁m₂/r². If the case involves a dipole, use τ = MB sinθ and U = -MB cosθ.
Case Study 18Case study based on magnetic force balancing weight.
Scenario: A student observes magnetic force balancing weight in a school laboratory.
Questions: Identify the field direction, write the relevant formula, explain the physical meaning, and mention one common mistake.
Solution: Use magnetic field line rules, magnetic dipole formulas and Gauss law where required. If the case involves force balance, use F_magnetic = mg and F = (μ₀/4π)m₁m₂/r². If the case involves a dipole, use τ = MB sinθ and U = -MB cosθ.
Questions: Identify the field direction, write the relevant formula, explain the physical meaning, and mention one common mistake.
Solution: Use magnetic field line rules, magnetic dipole formulas and Gauss law where required. If the case involves force balance, use F_magnetic = mg and F = (μ₀/4π)m₁m₂/r². If the case involves a dipole, use τ = MB sinθ and U = -MB cosθ.
Case Study 19Case study based on bar magnet field lines.
Scenario: A student observes bar magnet field lines in a school laboratory.
Questions: Identify the field direction, write the relevant formula, explain the physical meaning, and mention one common mistake.
Solution: Use magnetic field line rules, magnetic dipole formulas and Gauss law where required. If the case involves force balance, use F_magnetic = mg and F = (μ₀/4π)m₁m₂/r². If the case involves a dipole, use τ = MB sinθ and U = -MB cosθ.
Questions: Identify the field direction, write the relevant formula, explain the physical meaning, and mention one common mistake.
Solution: Use magnetic field line rules, magnetic dipole formulas and Gauss law where required. If the case involves force balance, use F_magnetic = mg and F = (μ₀/4π)m₁m₂/r². If the case involves a dipole, use τ = MB sinθ and U = -MB cosθ.
Case Study 20Case study based on broken magnet.
Scenario: A student observes broken magnet in a school laboratory.
Questions: Identify the field direction, write the relevant formula, explain the physical meaning, and mention one common mistake.
Solution: Use magnetic field line rules, magnetic dipole formulas and Gauss law where required. If the case involves force balance, use F_magnetic = mg and F = (μ₀/4π)m₁m₂/r². If the case involves a dipole, use τ = MB sinθ and U = -MB cosθ.
Questions: Identify the field direction, write the relevant formula, explain the physical meaning, and mention one common mistake.
Solution: Use magnetic field line rules, magnetic dipole formulas and Gauss law where required. If the case involves force balance, use F_magnetic = mg and F = (μ₀/4π)m₁m₂/r². If the case involves a dipole, use τ = MB sinθ and U = -MB cosθ.
16. Graphs and Diagram Revision
Original classroom SVG diagram redrawn for Kumar Physics Classes notes. NCERT Class 12 Physics concept flow used as reference.
Original classroom SVG diagram redrawn for Kumar Physics Classes notes. NCERT Class 12 Physics concept flow used as reference.
Original classroom SVG diagram redrawn for Kumar Physics Classes notes. NCERT Class 12 Physics concept flow used as reference.
Original classroom SVG diagram redrawn for Kumar Physics Classes notes. NCERT Class 12 Physics concept flow used as reference.
Original classroom SVG diagram redrawn for Kumar Physics Classes notes. NCERT Class 12 Physics concept flow used as reference.
Original classroom SVG diagram redrawn for Kumar Physics Classes notes. NCERT Class 12 Physics concept flow used as reference.
Original classroom SVG diagram redrawn for Kumar Physics Classes notes. NCERT Class 12 Physics concept flow used as reference.
Original classroom SVG diagram redrawn for Kumar Physics Classes notes. NCERT Class 12 Physics concept flow used as reference.
B_axial decreases as 1/r³ for a short magnet.
B_equatorial also decreases as 1/r³ but is half of axial field at same distance.
U versus θ follows -cosθ curve.
Gauss law flux through closed surface is zero.
17. Final Revision Sheet
Magnetic moment
M = m × 2lCoulomb law
F = (μ₀/4π)m₁m₂/r²Axial field
B_axial = (μ₀/4π)2Mr/(r²-l²)²Short magnet axial
B_axial = (μ₀/4π)2M/r³Equatorial field
B_eq = (μ₀/4π)M/(r²+l²)³ᐟ²Short magnet equatorial
B_eq = (μ₀/4π)M/r³Torque
τ = MB sinθPotential energy
U = -MB cosθMagnetic flux
ΦB = BA cosθGauss law
∮B · dA = 0Axial vs Equatorial
| Point | Direction | Short magnet formula |
|---|---|---|
| Axial | Along magnetic moment | (μ₀/4π)2M/r³ |
| Equatorial | Opposite magnetic moment | (μ₀/4π)M/r³ |
NEET and JEE Traps
Check axial/equatorial point before formula.
Remember magnetic moment direction S to N.
Gauss law of magnetism gives zero closed-surface flux.
Broken magnet never creates monopole.
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