Moving Coil Galvanometer

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Moving Coil Galvanometer

A complete premium Physics study page by Kumar Sir covering construction, radial magnetic field, torque balance, current sensitivity, voltage sensitivity, figure of merit, ammeter-voltmeter conversion, MCQs, case studies and revision notes.

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1. Introduction

A moving coil galvanometer is a sensitive instrument used to detect and measure small electric currents. It is one of the most important current electricity and magnetism instruments in CBSE Class 12 Physics, NEET, IIT JEE, JEE Advanced, IB Physics, IGCSE, ICSE and A-Level Physics.

The instrument works on the torque experienced by a current carrying coil placed in a magnetic field. Its deflection is proportional to the current, so it can be calibrated to measure current.

2. NCERT-Style Diagram

NCERT-style moving coil galvanometer diagram
Moving coil galvanometer: original educational diagram NS soft iron core strong radial magnetic field B rectangular moving coil: N turns, current I torsion head phosphor bronze suspension Sp spring / suspension restoring couple pointer and scale terminal +terminal − magnetic torque
Reference: NCERT Class 12 Physics, Moving Charges and Magnetism. Diagram redrawn as an original educational SVG for classroom notes.

This original educational SVG shows the standard scientific components: permanent concave pole pieces, strong radial magnetic field, soft iron core, rectangular moving coil, suspension strip, torsion head, pointer, scale, terminals, spring connection, restoring couple and magnetic torque direction.

3. Construction of Moving Coil Galvanometer

Rectangular coil of many turns of light insulated copper wire.
Coil wound on a light metallic frame.
Coil suspended between concave magnetic pole pieces.
Soft iron cylindrical core placed inside coil.
Radial magnetic field between pole pieces and core.
Phosphor bronze strip provides suspension and current path.
Lower spring completes circuit and gives restoring torque.
Pointer and scale measure deflection.
Terminals allow current entry and exit.

Concave pole pieces and soft iron core produce a strong radial field. The coil is made light to reduce inertia. Phosphor bronze is used because it has high tensile strength, elasticity and good conductivity.

4. Principle of Moving Coil Galvanometer

A current carrying coil placed in a magnetic field experiences torque. The torque rotates the coil until it is balanced by the restoring torque of the suspension spring.

General torqueτ = NBIA sinα
Radial fieldα = 90°, sinα = 1
Deflecting torqueτ = NBIA

5. Radial Magnetic Field

Radial magnetic field in a moving coil galvanometer
Concave poles and soft iron core produce radial magnetic field NS area vector A and m B In radial field, A remains perpendicular to B, so α = 90° and τ = NBIA.
Reference: NCERT Class 12 Physics, Moving Charges and Magnetism. Diagram redrawn as an original educational SVG for classroom notes.

In a moving coil galvanometer, the magnetic field is made radial by concave pole pieces and a soft iron core. In radial field, the plane of the coil remains parallel to the magnetic field and the area vector remains perpendicular to the magnetic field for all deflections. Therefore torque remains maximum and directly proportional to current.

DerivationCBSE • NEET • JEE

6. Mathematical Working

NCERT-style moving coil galvanometer diagram
Moving coil galvanometer: original educational diagram NS soft iron core strong radial magnetic field B rectangular moving coil: N turns, current I torsion head phosphor bronze suspension Sp spring / suspension restoring couple pointer and scale terminal +terminal − magnetic torque
Reference: NCERT Class 12 Physics, Moving Charges and Magnetism. Diagram redrawn as an original educational SVG for classroom notes.
Given / Symbols:
N = number of turns, B = magnetic field, I = current, A = area of coil, k = torsional constant, θ = angular deflection.
Assumptions:
Radial magnetic field; steady current; spring obeys Hooke's law for torsion; friction is negligible.
1Magnetic deflecting torque on the coil is τ_m = NBIA.
2Restoring torque due to suspension spring is τ_r = kθ.
3At equilibrium, deflecting torque equals restoring torque.
4Therefore NBIA = kθ.
5Solving for current gives I = kθ/NBA.
6Solving for deflection gives θ = NBAI/k.
7Since N, B, A and k are constants for the instrument, θ ∝ I.
8Therefore the galvanometer scale is linear.
Final Result:I = kθ / NBA; θ = NBAI / k; θ ∝ I
Common mistake:
In radial field, use τ = NBIA, not τ = NBIA sinθ.

7. Torsional Constant and Suspension Strip

The suspension strip provides restoring torque: τ = kθ. Here k is the torsional constant of the suspension strip. Phosphor bronze is preferred because it has high tensile strength, small torsional constant, elastic behaviour, good electrical conductivity, and it can provide both current path and restoring torque.

Restoring torqueτ = kθ
Small k giveslarger sensitivity

8. Current Sensitivity

Current sensitivity is the deflection produced per unit current.

DefinitionSᵢ = θ/I
Using θ = NBAI/kSᵢ = NBA/k

Current sensitivity can be increased by increasing N, B or A, and by decreasing torsional constant k.

9. Voltage Sensitivity

Voltage sensitivity is deflection produced per unit voltage.

DefinitionSᵥ = θ/V
Since V = IGSᵥ = θ/IG
Final resultSᵥ = NBA/kG

Increasing current sensitivity does not always increase voltage sensitivity because resistance G may also increase.

10. Figure of Merit

Figure of merit is the current required to produce one scale division deflection.

Definitionk_g = I/θ
Using I = kθ/NBAk_g = k/NBA

A smaller figure of merit means the galvanometer is more sensitive.

11. Conversion of Galvanometer

Conversion of galvanometer into ammeter and voltmeter
Galvanometer conversion circuits Ammeter: shunt S in parallel G S S = IgG/(I − Ig) Voltmeter: high R in series G R R = V/Ig − G
Reference: NCERT Class 12 Physics, Moving Charges and Magnetism. Diagram redrawn as an original educational SVG for classroom notes.
Ammeter conversionS = IgG/(I - Ig)
Voltmeter conversionR = V/Ig - G

To convert into ammeter, connect a low resistance shunt in parallel. To convert into voltmeter, connect a high resistance in series.

12. Limitations

Limitation 1Cannot directly measure large currents.
Limitation 2Cannot directly measure large voltages.
Limitation 3Delicate instrument.
Limitation 4Mainly suitable for DC measurement.
Limitation 5Cannot directly measure AC without rectification.
Limitation 6Mechanical friction may cause error.
Limitation 7Temperature affects resistance and spring constant.
Limitation 8Excess current may damage the coil.

13. NCERT / CBSE Important Points

Works on torque on current carrying coil.
Radial magnetic field makes torque maximum.
Deflection is directly proportional to current.
Concave pole pieces produce radial field.
Soft iron core increases magnetic field.
Phosphor bronze strip provides restoring torque.
Current sensitivity = NBA/k.
Voltage sensitivity = NBA/kG.
Can be converted into ammeter or voltmeter.

14. Common Student Mistakes

Mistake 1Confusing current sensitivity and voltage sensitivity.

Correction: Start from NBIA = kθ, then choose the correct sensitivity or conversion formula.

Mistake 2Forgetting radial magnetic field condition.

Correction: Start from NBIA = kθ, then choose the correct sensitivity or conversion formula.

Mistake 3Writing τ = NBIA sinθ instead of τ = NBIA in radial field.

Correction: Start from NBIA = kθ, then choose the correct sensitivity or conversion formula.

Mistake 4Confusing torsional constant k with figure of merit.

Correction: Start from NBIA = kθ, then choose the correct sensitivity or conversion formula.

Mistake 5Forgetting role of soft iron core.

Correction: Start from NBIA = kθ, then choose the correct sensitivity or conversion formula.

Mistake 6Forgetting why concave poles are used.

Correction: Start from NBIA = kθ, then choose the correct sensitivity or conversion formula.

Mistake 7Confusing ammeter and voltmeter conversion.

Correction: Start from NBIA = kθ, then choose the correct sensitivity or conversion formula.

Mistake 8Using wrong shunt formula.

Correction: Start from NBIA = kθ, then choose the correct sensitivity or conversion formula.

Mistake 9Forgetting galvanometer is delicate.

Correction: Start from NBIA = kθ, then choose the correct sensitivity or conversion formula.

Mistake 10Assuming current sensitivity always increases voltage sensitivity.

Correction: Start from NBIA = kθ, then choose the correct sensitivity or conversion formula.

15. Exam Question Bank With Solutions

A. CBSE Board Questions

CBSE Theory Question 1Explain construction of moving coil galvanometer.
Answer: A moving coil galvanometer uses a light rectangular coil suspended in a strong radial magnetic field between concave pole pieces and a soft iron core. Magnetic torque is NBIA and restoring torque is kθ. At equilibrium, NBIA = kθ, so I = kθ/NBA. This proves deflection is proportional to current. For conversion, use shunt S = IgG/(I − Ig) for ammeter and series resistance R = V/Ig − G for voltmeter.
CBSE Theory Question 2Why are concave pole pieces used in a moving coil galvanometer?
Answer: A moving coil galvanometer uses a light rectangular coil suspended in a strong radial magnetic field between concave pole pieces and a soft iron core. Magnetic torque is NBIA and restoring torque is kθ. At equilibrium, NBIA = kθ, so I = kθ/NBA. This proves deflection is proportional to current. For conversion, use shunt S = IgG/(I − Ig) for ammeter and series resistance R = V/Ig − G for voltmeter.
CBSE Theory Question 3Why is soft iron core used?
Answer: A moving coil galvanometer uses a light rectangular coil suspended in a strong radial magnetic field between concave pole pieces and a soft iron core. Magnetic torque is NBIA and restoring torque is kθ. At equilibrium, NBIA = kθ, so I = kθ/NBA. This proves deflection is proportional to current. For conversion, use shunt S = IgG/(I − Ig) for ammeter and series resistance R = V/Ig − G for voltmeter.
CBSE Theory Question 4Derive I = kθ/NBA for a moving coil galvanometer.
Answer: A moving coil galvanometer uses a light rectangular coil suspended in a strong radial magnetic field between concave pole pieces and a soft iron core. Magnetic torque is NBIA and restoring torque is kθ. At equilibrium, NBIA = kθ, so I = kθ/NBA. This proves deflection is proportional to current. For conversion, use shunt S = IgG/(I − Ig) for ammeter and series resistance R = V/Ig − G for voltmeter.
CBSE Theory Question 5Define current sensitivity and derive its expression.
Answer: A moving coil galvanometer uses a light rectangular coil suspended in a strong radial magnetic field between concave pole pieces and a soft iron core. Magnetic torque is NBIA and restoring torque is kθ. At equilibrium, NBIA = kθ, so I = kθ/NBA. This proves deflection is proportional to current. For conversion, use shunt S = IgG/(I − Ig) for ammeter and series resistance R = V/Ig − G for voltmeter.
CBSE Theory Question 6Define voltage sensitivity and derive its expression.
Answer: A moving coil galvanometer uses a light rectangular coil suspended in a strong radial magnetic field between concave pole pieces and a soft iron core. Magnetic torque is NBIA and restoring torque is kθ. At equilibrium, NBIA = kθ, so I = kθ/NBA. This proves deflection is proportional to current. For conversion, use shunt S = IgG/(I − Ig) for ammeter and series resistance R = V/Ig − G for voltmeter.
CBSE Theory Question 7Define figure of merit and explain its significance.
Answer: A moving coil galvanometer uses a light rectangular coil suspended in a strong radial magnetic field between concave pole pieces and a soft iron core. Magnetic torque is NBIA and restoring torque is kθ. At equilibrium, NBIA = kθ, so I = kθ/NBA. This proves deflection is proportional to current. For conversion, use shunt S = IgG/(I − Ig) for ammeter and series resistance R = V/Ig − G for voltmeter.
CBSE Theory Question 8How is a galvanometer converted into an ammeter?
Answer: A moving coil galvanometer uses a light rectangular coil suspended in a strong radial magnetic field between concave pole pieces and a soft iron core. Magnetic torque is NBIA and restoring torque is kθ. At equilibrium, NBIA = kθ, so I = kθ/NBA. This proves deflection is proportional to current. For conversion, use shunt S = IgG/(I − Ig) for ammeter and series resistance R = V/Ig − G for voltmeter.
CBSE Theory Question 9How is a galvanometer converted into a voltmeter?
Answer: A moving coil galvanometer uses a light rectangular coil suspended in a strong radial magnetic field between concave pole pieces and a soft iron core. Magnetic torque is NBIA and restoring torque is kθ. At equilibrium, NBIA = kθ, so I = kθ/NBA. This proves deflection is proportional to current. For conversion, use shunt S = IgG/(I − Ig) for ammeter and series resistance R = V/Ig − G for voltmeter.
CBSE Theory Question 10Why is moving coil galvanometer mainly suitable for DC?
Answer: A moving coil galvanometer uses a light rectangular coil suspended in a strong radial magnetic field between concave pole pieces and a soft iron core. Magnetic torque is NBIA and restoring torque is kθ. At equilibrium, NBIA = kθ, so I = kθ/NBA. This proves deflection is proportional to current. For conversion, use shunt S = IgG/(I − Ig) for ammeter and series resistance R = V/Ig − G for voltmeter.
CBSE Theory Question 11Explain construction of moving coil galvanometer.
Answer: A moving coil galvanometer uses a light rectangular coil suspended in a strong radial magnetic field between concave pole pieces and a soft iron core. Magnetic torque is NBIA and restoring torque is kθ. At equilibrium, NBIA = kθ, so I = kθ/NBA. This proves deflection is proportional to current. For conversion, use shunt S = IgG/(I − Ig) for ammeter and series resistance R = V/Ig − G for voltmeter.
CBSE Theory Question 12Why are concave pole pieces used in a moving coil galvanometer?
Answer: A moving coil galvanometer uses a light rectangular coil suspended in a strong radial magnetic field between concave pole pieces and a soft iron core. Magnetic torque is NBIA and restoring torque is kθ. At equilibrium, NBIA = kθ, so I = kθ/NBA. This proves deflection is proportional to current. For conversion, use shunt S = IgG/(I − Ig) for ammeter and series resistance R = V/Ig − G for voltmeter.
CBSE Theory Question 13Why is soft iron core used?
Answer: A moving coil galvanometer uses a light rectangular coil suspended in a strong radial magnetic field between concave pole pieces and a soft iron core. Magnetic torque is NBIA and restoring torque is kθ. At equilibrium, NBIA = kθ, so I = kθ/NBA. This proves deflection is proportional to current. For conversion, use shunt S = IgG/(I − Ig) for ammeter and series resistance R = V/Ig − G for voltmeter.
CBSE Theory Question 14Derive I = kθ/NBA for a moving coil galvanometer.
Answer: A moving coil galvanometer uses a light rectangular coil suspended in a strong radial magnetic field between concave pole pieces and a soft iron core. Magnetic torque is NBIA and restoring torque is kθ. At equilibrium, NBIA = kθ, so I = kθ/NBA. This proves deflection is proportional to current. For conversion, use shunt S = IgG/(I − Ig) for ammeter and series resistance R = V/Ig − G for voltmeter.
CBSE Theory Question 15Define current sensitivity and derive its expression.
Answer: A moving coil galvanometer uses a light rectangular coil suspended in a strong radial magnetic field between concave pole pieces and a soft iron core. Magnetic torque is NBIA and restoring torque is kθ. At equilibrium, NBIA = kθ, so I = kθ/NBA. This proves deflection is proportional to current. For conversion, use shunt S = IgG/(I − Ig) for ammeter and series resistance R = V/Ig − G for voltmeter.
CBSE Theory Question 16Define voltage sensitivity and derive its expression.
Answer: A moving coil galvanometer uses a light rectangular coil suspended in a strong radial magnetic field between concave pole pieces and a soft iron core. Magnetic torque is NBIA and restoring torque is kθ. At equilibrium, NBIA = kθ, so I = kθ/NBA. This proves deflection is proportional to current. For conversion, use shunt S = IgG/(I − Ig) for ammeter and series resistance R = V/Ig − G for voltmeter.
CBSE Theory Question 17Define figure of merit and explain its significance.
Answer: A moving coil galvanometer uses a light rectangular coil suspended in a strong radial magnetic field between concave pole pieces and a soft iron core. Magnetic torque is NBIA and restoring torque is kθ. At equilibrium, NBIA = kθ, so I = kθ/NBA. This proves deflection is proportional to current. For conversion, use shunt S = IgG/(I − Ig) for ammeter and series resistance R = V/Ig − G for voltmeter.
CBSE Theory Question 18How is a galvanometer converted into an ammeter?
Answer: A moving coil galvanometer uses a light rectangular coil suspended in a strong radial magnetic field between concave pole pieces and a soft iron core. Magnetic torque is NBIA and restoring torque is kθ. At equilibrium, NBIA = kθ, so I = kθ/NBA. This proves deflection is proportional to current. For conversion, use shunt S = IgG/(I − Ig) for ammeter and series resistance R = V/Ig − G for voltmeter.
CBSE Theory Question 19How is a galvanometer converted into a voltmeter?
Answer: A moving coil galvanometer uses a light rectangular coil suspended in a strong radial magnetic field between concave pole pieces and a soft iron core. Magnetic torque is NBIA and restoring torque is kθ. At equilibrium, NBIA = kθ, so I = kθ/NBA. This proves deflection is proportional to current. For conversion, use shunt S = IgG/(I − Ig) for ammeter and series resistance R = V/Ig − G for voltmeter.
CBSE Theory Question 20Why is moving coil galvanometer mainly suitable for DC?
Answer: A moving coil galvanometer uses a light rectangular coil suspended in a strong radial magnetic field between concave pole pieces and a soft iron core. Magnetic torque is NBIA and restoring torque is kθ. At equilibrium, NBIA = kθ, so I = kθ/NBA. This proves deflection is proportional to current. For conversion, use shunt S = IgG/(I − Ig) for ammeter and series resistance R = V/Ig − G for voltmeter.
CBSE Theory Question 21Explain construction of moving coil galvanometer.
Answer: A moving coil galvanometer uses a light rectangular coil suspended in a strong radial magnetic field between concave pole pieces and a soft iron core. Magnetic torque is NBIA and restoring torque is kθ. At equilibrium, NBIA = kθ, so I = kθ/NBA. This proves deflection is proportional to current. For conversion, use shunt S = IgG/(I − Ig) for ammeter and series resistance R = V/Ig − G for voltmeter.
CBSE Theory Question 22Why are concave pole pieces used in a moving coil galvanometer?
Answer: A moving coil galvanometer uses a light rectangular coil suspended in a strong radial magnetic field between concave pole pieces and a soft iron core. Magnetic torque is NBIA and restoring torque is kθ. At equilibrium, NBIA = kθ, so I = kθ/NBA. This proves deflection is proportional to current. For conversion, use shunt S = IgG/(I − Ig) for ammeter and series resistance R = V/Ig − G for voltmeter.
CBSE Theory Question 23Why is soft iron core used?
Answer: A moving coil galvanometer uses a light rectangular coil suspended in a strong radial magnetic field between concave pole pieces and a soft iron core. Magnetic torque is NBIA and restoring torque is kθ. At equilibrium, NBIA = kθ, so I = kθ/NBA. This proves deflection is proportional to current. For conversion, use shunt S = IgG/(I − Ig) for ammeter and series resistance R = V/Ig − G for voltmeter.
CBSE Theory Question 24Derive I = kθ/NBA for a moving coil galvanometer.
Answer: A moving coil galvanometer uses a light rectangular coil suspended in a strong radial magnetic field between concave pole pieces and a soft iron core. Magnetic torque is NBIA and restoring torque is kθ. At equilibrium, NBIA = kθ, so I = kθ/NBA. This proves deflection is proportional to current. For conversion, use shunt S = IgG/(I − Ig) for ammeter and series resistance R = V/Ig − G for voltmeter.
CBSE Theory Question 25Define current sensitivity and derive its expression.
Answer: A moving coil galvanometer uses a light rectangular coil suspended in a strong radial magnetic field between concave pole pieces and a soft iron core. Magnetic torque is NBIA and restoring torque is kθ. At equilibrium, NBIA = kθ, so I = kθ/NBA. This proves deflection is proportional to current. For conversion, use shunt S = IgG/(I − Ig) for ammeter and series resistance R = V/Ig − G for voltmeter.
CBSE Derivation Question 1Explain construction of moving coil galvanometer.
Answer: A moving coil galvanometer uses a light rectangular coil suspended in a strong radial magnetic field between concave pole pieces and a soft iron core. Magnetic torque is NBIA and restoring torque is kθ. At equilibrium, NBIA = kθ, so I = kθ/NBA. This proves deflection is proportional to current. For conversion, use shunt S = IgG/(I − Ig) for ammeter and series resistance R = V/Ig − G for voltmeter.
CBSE Derivation Question 2Why are concave pole pieces used in a moving coil galvanometer?
Answer: A moving coil galvanometer uses a light rectangular coil suspended in a strong radial magnetic field between concave pole pieces and a soft iron core. Magnetic torque is NBIA and restoring torque is kθ. At equilibrium, NBIA = kθ, so I = kθ/NBA. This proves deflection is proportional to current. For conversion, use shunt S = IgG/(I − Ig) for ammeter and series resistance R = V/Ig − G for voltmeter.
CBSE Derivation Question 3Why is soft iron core used?
Answer: A moving coil galvanometer uses a light rectangular coil suspended in a strong radial magnetic field between concave pole pieces and a soft iron core. Magnetic torque is NBIA and restoring torque is kθ. At equilibrium, NBIA = kθ, so I = kθ/NBA. This proves deflection is proportional to current. For conversion, use shunt S = IgG/(I − Ig) for ammeter and series resistance R = V/Ig − G for voltmeter.
CBSE Derivation Question 4Derive I = kθ/NBA for a moving coil galvanometer.
Answer: A moving coil galvanometer uses a light rectangular coil suspended in a strong radial magnetic field between concave pole pieces and a soft iron core. Magnetic torque is NBIA and restoring torque is kθ. At equilibrium, NBIA = kθ, so I = kθ/NBA. This proves deflection is proportional to current. For conversion, use shunt S = IgG/(I − Ig) for ammeter and series resistance R = V/Ig − G for voltmeter.
CBSE Derivation Question 5Define current sensitivity and derive its expression.
Answer: A moving coil galvanometer uses a light rectangular coil suspended in a strong radial magnetic field between concave pole pieces and a soft iron core. Magnetic torque is NBIA and restoring torque is kθ. At equilibrium, NBIA = kθ, so I = kθ/NBA. This proves deflection is proportional to current. For conversion, use shunt S = IgG/(I − Ig) for ammeter and series resistance R = V/Ig − G for voltmeter.
CBSE Derivation Question 6Define voltage sensitivity and derive its expression.
Answer: A moving coil galvanometer uses a light rectangular coil suspended in a strong radial magnetic field between concave pole pieces and a soft iron core. Magnetic torque is NBIA and restoring torque is kθ. At equilibrium, NBIA = kθ, so I = kθ/NBA. This proves deflection is proportional to current. For conversion, use shunt S = IgG/(I − Ig) for ammeter and series resistance R = V/Ig − G for voltmeter.
CBSE Derivation Question 7Define figure of merit and explain its significance.
Answer: A moving coil galvanometer uses a light rectangular coil suspended in a strong radial magnetic field between concave pole pieces and a soft iron core. Magnetic torque is NBIA and restoring torque is kθ. At equilibrium, NBIA = kθ, so I = kθ/NBA. This proves deflection is proportional to current. For conversion, use shunt S = IgG/(I − Ig) for ammeter and series resistance R = V/Ig − G for voltmeter.
CBSE Derivation Question 8How is a galvanometer converted into an ammeter?
Answer: A moving coil galvanometer uses a light rectangular coil suspended in a strong radial magnetic field between concave pole pieces and a soft iron core. Magnetic torque is NBIA and restoring torque is kθ. At equilibrium, NBIA = kθ, so I = kθ/NBA. This proves deflection is proportional to current. For conversion, use shunt S = IgG/(I − Ig) for ammeter and series resistance R = V/Ig − G for voltmeter.
CBSE Derivation Question 9How is a galvanometer converted into a voltmeter?
Answer: A moving coil galvanometer uses a light rectangular coil suspended in a strong radial magnetic field between concave pole pieces and a soft iron core. Magnetic torque is NBIA and restoring torque is kθ. At equilibrium, NBIA = kθ, so I = kθ/NBA. This proves deflection is proportional to current. For conversion, use shunt S = IgG/(I − Ig) for ammeter and series resistance R = V/Ig − G for voltmeter.
CBSE Derivation Question 10Why is moving coil galvanometer mainly suitable for DC?
Answer: A moving coil galvanometer uses a light rectangular coil suspended in a strong radial magnetic field between concave pole pieces and a soft iron core. Magnetic torque is NBIA and restoring torque is kθ. At equilibrium, NBIA = kθ, so I = kθ/NBA. This proves deflection is proportional to current. For conversion, use shunt S = IgG/(I − Ig) for ammeter and series resistance R = V/Ig − G for voltmeter.
CBSE Derivation Question 11Explain construction of moving coil galvanometer.
Answer: A moving coil galvanometer uses a light rectangular coil suspended in a strong radial magnetic field between concave pole pieces and a soft iron core. Magnetic torque is NBIA and restoring torque is kθ. At equilibrium, NBIA = kθ, so I = kθ/NBA. This proves deflection is proportional to current. For conversion, use shunt S = IgG/(I − Ig) for ammeter and series resistance R = V/Ig − G for voltmeter.
CBSE Derivation Question 12Why are concave pole pieces used in a moving coil galvanometer?
Answer: A moving coil galvanometer uses a light rectangular coil suspended in a strong radial magnetic field between concave pole pieces and a soft iron core. Magnetic torque is NBIA and restoring torque is kθ. At equilibrium, NBIA = kθ, so I = kθ/NBA. This proves deflection is proportional to current. For conversion, use shunt S = IgG/(I − Ig) for ammeter and series resistance R = V/Ig − G for voltmeter.
CBSE Derivation Question 13Why is soft iron core used?
Answer: A moving coil galvanometer uses a light rectangular coil suspended in a strong radial magnetic field between concave pole pieces and a soft iron core. Magnetic torque is NBIA and restoring torque is kθ. At equilibrium, NBIA = kθ, so I = kθ/NBA. This proves deflection is proportional to current. For conversion, use shunt S = IgG/(I − Ig) for ammeter and series resistance R = V/Ig − G for voltmeter.
CBSE Derivation Question 14Derive I = kθ/NBA for a moving coil galvanometer.
Answer: A moving coil galvanometer uses a light rectangular coil suspended in a strong radial magnetic field between concave pole pieces and a soft iron core. Magnetic torque is NBIA and restoring torque is kθ. At equilibrium, NBIA = kθ, so I = kθ/NBA. This proves deflection is proportional to current. For conversion, use shunt S = IgG/(I − Ig) for ammeter and series resistance R = V/Ig − G for voltmeter.
CBSE Derivation Question 15Define current sensitivity and derive its expression.
Answer: A moving coil galvanometer uses a light rectangular coil suspended in a strong radial magnetic field between concave pole pieces and a soft iron core. Magnetic torque is NBIA and restoring torque is kθ. At equilibrium, NBIA = kθ, so I = kθ/NBA. This proves deflection is proportional to current. For conversion, use shunt S = IgG/(I − Ig) for ammeter and series resistance R = V/Ig − G for voltmeter.
CBSE Derivation Question 16Define voltage sensitivity and derive its expression.
Answer: A moving coil galvanometer uses a light rectangular coil suspended in a strong radial magnetic field between concave pole pieces and a soft iron core. Magnetic torque is NBIA and restoring torque is kθ. At equilibrium, NBIA = kθ, so I = kθ/NBA. This proves deflection is proportional to current. For conversion, use shunt S = IgG/(I − Ig) for ammeter and series resistance R = V/Ig − G for voltmeter.
CBSE Derivation Question 17Define figure of merit and explain its significance.
Answer: A moving coil galvanometer uses a light rectangular coil suspended in a strong radial magnetic field between concave pole pieces and a soft iron core. Magnetic torque is NBIA and restoring torque is kθ. At equilibrium, NBIA = kθ, so I = kθ/NBA. This proves deflection is proportional to current. For conversion, use shunt S = IgG/(I − Ig) for ammeter and series resistance R = V/Ig − G for voltmeter.
CBSE Derivation Question 18How is a galvanometer converted into an ammeter?
Answer: A moving coil galvanometer uses a light rectangular coil suspended in a strong radial magnetic field between concave pole pieces and a soft iron core. Magnetic torque is NBIA and restoring torque is kθ. At equilibrium, NBIA = kθ, so I = kθ/NBA. This proves deflection is proportional to current. For conversion, use shunt S = IgG/(I − Ig) for ammeter and series resistance R = V/Ig − G for voltmeter.
CBSE Derivation Question 19How is a galvanometer converted into a voltmeter?
Answer: A moving coil galvanometer uses a light rectangular coil suspended in a strong radial magnetic field between concave pole pieces and a soft iron core. Magnetic torque is NBIA and restoring torque is kθ. At equilibrium, NBIA = kθ, so I = kθ/NBA. This proves deflection is proportional to current. For conversion, use shunt S = IgG/(I − Ig) for ammeter and series resistance R = V/Ig − G for voltmeter.
CBSE Derivation Question 20Why is moving coil galvanometer mainly suitable for DC?
Answer: A moving coil galvanometer uses a light rectangular coil suspended in a strong radial magnetic field between concave pole pieces and a soft iron core. Magnetic torque is NBIA and restoring torque is kθ. At equilibrium, NBIA = kθ, so I = kθ/NBA. This proves deflection is proportional to current. For conversion, use shunt S = IgG/(I − Ig) for ammeter and series resistance R = V/Ig − G for voltmeter.
CBSE Numerical Question 1Explain construction of moving coil galvanometer.
Answer: A moving coil galvanometer uses a light rectangular coil suspended in a strong radial magnetic field between concave pole pieces and a soft iron core. Magnetic torque is NBIA and restoring torque is kθ. At equilibrium, NBIA = kθ, so I = kθ/NBA. This proves deflection is proportional to current. For conversion, use shunt S = IgG/(I − Ig) for ammeter and series resistance R = V/Ig − G for voltmeter.
CBSE Numerical Question 2Why are concave pole pieces used in a moving coil galvanometer?
Answer: A moving coil galvanometer uses a light rectangular coil suspended in a strong radial magnetic field between concave pole pieces and a soft iron core. Magnetic torque is NBIA and restoring torque is kθ. At equilibrium, NBIA = kθ, so I = kθ/NBA. This proves deflection is proportional to current. For conversion, use shunt S = IgG/(I − Ig) for ammeter and series resistance R = V/Ig − G for voltmeter.
CBSE Numerical Question 3Why is soft iron core used?
Answer: A moving coil galvanometer uses a light rectangular coil suspended in a strong radial magnetic field between concave pole pieces and a soft iron core. Magnetic torque is NBIA and restoring torque is kθ. At equilibrium, NBIA = kθ, so I = kθ/NBA. This proves deflection is proportional to current. For conversion, use shunt S = IgG/(I − Ig) for ammeter and series resistance R = V/Ig − G for voltmeter.
CBSE Numerical Question 4Derive I = kθ/NBA for a moving coil galvanometer.
Answer: A moving coil galvanometer uses a light rectangular coil suspended in a strong radial magnetic field between concave pole pieces and a soft iron core. Magnetic torque is NBIA and restoring torque is kθ. At equilibrium, NBIA = kθ, so I = kθ/NBA. This proves deflection is proportional to current. For conversion, use shunt S = IgG/(I − Ig) for ammeter and series resistance R = V/Ig − G for voltmeter.
CBSE Numerical Question 5Define current sensitivity and derive its expression.
Answer: A moving coil galvanometer uses a light rectangular coil suspended in a strong radial magnetic field between concave pole pieces and a soft iron core. Magnetic torque is NBIA and restoring torque is kθ. At equilibrium, NBIA = kθ, so I = kθ/NBA. This proves deflection is proportional to current. For conversion, use shunt S = IgG/(I − Ig) for ammeter and series resistance R = V/Ig − G for voltmeter.
CBSE Numerical Question 6Define voltage sensitivity and derive its expression.
Answer: A moving coil galvanometer uses a light rectangular coil suspended in a strong radial magnetic field between concave pole pieces and a soft iron core. Magnetic torque is NBIA and restoring torque is kθ. At equilibrium, NBIA = kθ, so I = kθ/NBA. This proves deflection is proportional to current. For conversion, use shunt S = IgG/(I − Ig) for ammeter and series resistance R = V/Ig − G for voltmeter.
CBSE Numerical Question 7Define figure of merit and explain its significance.
Answer: A moving coil galvanometer uses a light rectangular coil suspended in a strong radial magnetic field between concave pole pieces and a soft iron core. Magnetic torque is NBIA and restoring torque is kθ. At equilibrium, NBIA = kθ, so I = kθ/NBA. This proves deflection is proportional to current. For conversion, use shunt S = IgG/(I − Ig) for ammeter and series resistance R = V/Ig − G for voltmeter.
CBSE Numerical Question 8How is a galvanometer converted into an ammeter?
Answer: A moving coil galvanometer uses a light rectangular coil suspended in a strong radial magnetic field between concave pole pieces and a soft iron core. Magnetic torque is NBIA and restoring torque is kθ. At equilibrium, NBIA = kθ, so I = kθ/NBA. This proves deflection is proportional to current. For conversion, use shunt S = IgG/(I − Ig) for ammeter and series resistance R = V/Ig − G for voltmeter.
CBSE Numerical Question 9How is a galvanometer converted into a voltmeter?
Answer: A moving coil galvanometer uses a light rectangular coil suspended in a strong radial magnetic field between concave pole pieces and a soft iron core. Magnetic torque is NBIA and restoring torque is kθ. At equilibrium, NBIA = kθ, so I = kθ/NBA. This proves deflection is proportional to current. For conversion, use shunt S = IgG/(I − Ig) for ammeter and series resistance R = V/Ig − G for voltmeter.
CBSE Numerical Question 10Why is moving coil galvanometer mainly suitable for DC?
Answer: A moving coil galvanometer uses a light rectangular coil suspended in a strong radial magnetic field between concave pole pieces and a soft iron core. Magnetic torque is NBIA and restoring torque is kθ. At equilibrium, NBIA = kθ, so I = kθ/NBA. This proves deflection is proportional to current. For conversion, use shunt S = IgG/(I − Ig) for ammeter and series resistance R = V/Ig − G for voltmeter.
CBSE Numerical Question 11Explain construction of moving coil galvanometer.
Answer: A moving coil galvanometer uses a light rectangular coil suspended in a strong radial magnetic field between concave pole pieces and a soft iron core. Magnetic torque is NBIA and restoring torque is kθ. At equilibrium, NBIA = kθ, so I = kθ/NBA. This proves deflection is proportional to current. For conversion, use shunt S = IgG/(I − Ig) for ammeter and series resistance R = V/Ig − G for voltmeter.
CBSE Numerical Question 12Why are concave pole pieces used in a moving coil galvanometer?
Answer: A moving coil galvanometer uses a light rectangular coil suspended in a strong radial magnetic field between concave pole pieces and a soft iron core. Magnetic torque is NBIA and restoring torque is kθ. At equilibrium, NBIA = kθ, so I = kθ/NBA. This proves deflection is proportional to current. For conversion, use shunt S = IgG/(I − Ig) for ammeter and series resistance R = V/Ig − G for voltmeter.
CBSE Numerical Question 13Why is soft iron core used?
Answer: A moving coil galvanometer uses a light rectangular coil suspended in a strong radial magnetic field between concave pole pieces and a soft iron core. Magnetic torque is NBIA and restoring torque is kθ. At equilibrium, NBIA = kθ, so I = kθ/NBA. This proves deflection is proportional to current. For conversion, use shunt S = IgG/(I − Ig) for ammeter and series resistance R = V/Ig − G for voltmeter.
CBSE Numerical Question 14Derive I = kθ/NBA for a moving coil galvanometer.
Answer: A moving coil galvanometer uses a light rectangular coil suspended in a strong radial magnetic field between concave pole pieces and a soft iron core. Magnetic torque is NBIA and restoring torque is kθ. At equilibrium, NBIA = kθ, so I = kθ/NBA. This proves deflection is proportional to current. For conversion, use shunt S = IgG/(I − Ig) for ammeter and series resistance R = V/Ig − G for voltmeter.
CBSE Numerical Question 15Define current sensitivity and derive its expression.
Answer: A moving coil galvanometer uses a light rectangular coil suspended in a strong radial magnetic field between concave pole pieces and a soft iron core. Magnetic torque is NBIA and restoring torque is kθ. At equilibrium, NBIA = kθ, so I = kθ/NBA. This proves deflection is proportional to current. For conversion, use shunt S = IgG/(I − Ig) for ammeter and series resistance R = V/Ig − G for voltmeter.
CBSE Numerical Question 16Define voltage sensitivity and derive its expression.
Answer: A moving coil galvanometer uses a light rectangular coil suspended in a strong radial magnetic field between concave pole pieces and a soft iron core. Magnetic torque is NBIA and restoring torque is kθ. At equilibrium, NBIA = kθ, so I = kθ/NBA. This proves deflection is proportional to current. For conversion, use shunt S = IgG/(I − Ig) for ammeter and series resistance R = V/Ig − G for voltmeter.
CBSE Numerical Question 17Define figure of merit and explain its significance.
Answer: A moving coil galvanometer uses a light rectangular coil suspended in a strong radial magnetic field between concave pole pieces and a soft iron core. Magnetic torque is NBIA and restoring torque is kθ. At equilibrium, NBIA = kθ, so I = kθ/NBA. This proves deflection is proportional to current. For conversion, use shunt S = IgG/(I − Ig) for ammeter and series resistance R = V/Ig − G for voltmeter.
CBSE Numerical Question 18How is a galvanometer converted into an ammeter?
Answer: A moving coil galvanometer uses a light rectangular coil suspended in a strong radial magnetic field between concave pole pieces and a soft iron core. Magnetic torque is NBIA and restoring torque is kθ. At equilibrium, NBIA = kθ, so I = kθ/NBA. This proves deflection is proportional to current. For conversion, use shunt S = IgG/(I − Ig) for ammeter and series resistance R = V/Ig − G for voltmeter.
CBSE Numerical Question 19How is a galvanometer converted into a voltmeter?
Answer: A moving coil galvanometer uses a light rectangular coil suspended in a strong radial magnetic field between concave pole pieces and a soft iron core. Magnetic torque is NBIA and restoring torque is kθ. At equilibrium, NBIA = kθ, so I = kθ/NBA. This proves deflection is proportional to current. For conversion, use shunt S = IgG/(I − Ig) for ammeter and series resistance R = V/Ig − G for voltmeter.
CBSE Numerical Question 20Why is moving coil galvanometer mainly suitable for DC?
Answer: A moving coil galvanometer uses a light rectangular coil suspended in a strong radial magnetic field between concave pole pieces and a soft iron core. Magnetic torque is NBIA and restoring torque is kθ. At equilibrium, NBIA = kθ, so I = kθ/NBA. This proves deflection is proportional to current. For conversion, use shunt S = IgG/(I − Ig) for ammeter and series resistance R = V/Ig − G for voltmeter.
CBSE Numerical Question 21Explain construction of moving coil galvanometer.
Answer: A moving coil galvanometer uses a light rectangular coil suspended in a strong radial magnetic field between concave pole pieces and a soft iron core. Magnetic torque is NBIA and restoring torque is kθ. At equilibrium, NBIA = kθ, so I = kθ/NBA. This proves deflection is proportional to current. For conversion, use shunt S = IgG/(I − Ig) for ammeter and series resistance R = V/Ig − G for voltmeter.
CBSE Numerical Question 22Why are concave pole pieces used in a moving coil galvanometer?
Answer: A moving coil galvanometer uses a light rectangular coil suspended in a strong radial magnetic field between concave pole pieces and a soft iron core. Magnetic torque is NBIA and restoring torque is kθ. At equilibrium, NBIA = kθ, so I = kθ/NBA. This proves deflection is proportional to current. For conversion, use shunt S = IgG/(I − Ig) for ammeter and series resistance R = V/Ig − G for voltmeter.
CBSE Numerical Question 23Why is soft iron core used?
Answer: A moving coil galvanometer uses a light rectangular coil suspended in a strong radial magnetic field between concave pole pieces and a soft iron core. Magnetic torque is NBIA and restoring torque is kθ. At equilibrium, NBIA = kθ, so I = kθ/NBA. This proves deflection is proportional to current. For conversion, use shunt S = IgG/(I − Ig) for ammeter and series resistance R = V/Ig − G for voltmeter.
CBSE Numerical Question 24Derive I = kθ/NBA for a moving coil galvanometer.
Answer: A moving coil galvanometer uses a light rectangular coil suspended in a strong radial magnetic field between concave pole pieces and a soft iron core. Magnetic torque is NBIA and restoring torque is kθ. At equilibrium, NBIA = kθ, so I = kθ/NBA. This proves deflection is proportional to current. For conversion, use shunt S = IgG/(I − Ig) for ammeter and series resistance R = V/Ig − G for voltmeter.
CBSE Numerical Question 25Define current sensitivity and derive its expression.
Answer: A moving coil galvanometer uses a light rectangular coil suspended in a strong radial magnetic field between concave pole pieces and a soft iron core. Magnetic torque is NBIA and restoring torque is kθ. At equilibrium, NBIA = kθ, so I = kθ/NBA. This proves deflection is proportional to current. For conversion, use shunt S = IgG/(I − Ig) for ammeter and series resistance R = V/Ig − G for voltmeter.
Case Study 1construction and labels
Scenario: A moving coil galvanometer has N turns, coil area A, magnetic field B, galvanometer resistance G and torsional constant k. A current produces angular deflection θ.
Questions: find current, sensitivity, figure of merit or required shunt/series resistance.
Solution: Use NBIA = kθ, I = kθ/NBA, Sᵢ = NBA/k, Sᵥ = NBA/kG, k_g = k/NBA, S = IgG/(I − Ig), and R = V/Ig − G.
Case Study 2radial magnetic field
Scenario: A moving coil galvanometer has N turns, coil area A, magnetic field B, galvanometer resistance G and torsional constant k. A current produces angular deflection θ.
Questions: find current, sensitivity, figure of merit or required shunt/series resistance.
Solution: Use NBIA = kθ, I = kθ/NBA, Sᵢ = NBA/k, Sᵥ = NBA/kG, k_g = k/NBA, S = IgG/(I − Ig), and R = V/Ig − G.
Case Study 3current sensitivity
Scenario: A moving coil galvanometer has N turns, coil area A, magnetic field B, galvanometer resistance G and torsional constant k. A current produces angular deflection θ.
Questions: find current, sensitivity, figure of merit or required shunt/series resistance.
Solution: Use NBIA = kθ, I = kθ/NBA, Sᵢ = NBA/k, Sᵥ = NBA/kG, k_g = k/NBA, S = IgG/(I − Ig), and R = V/Ig − G.
Case Study 4voltage sensitivity
Scenario: A moving coil galvanometer has N turns, coil area A, magnetic field B, galvanometer resistance G and torsional constant k. A current produces angular deflection θ.
Questions: find current, sensitivity, figure of merit or required shunt/series resistance.
Solution: Use NBIA = kθ, I = kθ/NBA, Sᵢ = NBA/k, Sᵥ = NBA/kG, k_g = k/NBA, S = IgG/(I − Ig), and R = V/Ig − G.
Case Study 5figure of merit
Scenario: A moving coil galvanometer has N turns, coil area A, magnetic field B, galvanometer resistance G and torsional constant k. A current produces angular deflection θ.
Questions: find current, sensitivity, figure of merit or required shunt/series resistance.
Solution: Use NBIA = kθ, I = kθ/NBA, Sᵢ = NBA/k, Sᵥ = NBA/kG, k_g = k/NBA, S = IgG/(I − Ig), and R = V/Ig − G.
Case Study 6ammeter conversion
Scenario: A moving coil galvanometer has N turns, coil area A, magnetic field B, galvanometer resistance G and torsional constant k. A current produces angular deflection θ.
Questions: find current, sensitivity, figure of merit or required shunt/series resistance.
Solution: Use NBIA = kθ, I = kθ/NBA, Sᵢ = NBA/k, Sᵥ = NBA/kG, k_g = k/NBA, S = IgG/(I − Ig), and R = V/Ig − G.
Case Study 7voltmeter conversion
Scenario: A moving coil galvanometer has N turns, coil area A, magnetic field B, galvanometer resistance G and torsional constant k. A current produces angular deflection θ.
Questions: find current, sensitivity, figure of merit or required shunt/series resistance.
Solution: Use NBIA = kθ, I = kθ/NBA, Sᵢ = NBA/k, Sᵥ = NBA/kG, k_g = k/NBA, S = IgG/(I − Ig), and R = V/Ig − G.
Case Study 8torque balance
Scenario: A moving coil galvanometer has N turns, coil area A, magnetic field B, galvanometer resistance G and torsional constant k. A current produces angular deflection θ.
Questions: find current, sensitivity, figure of merit or required shunt/series resistance.
Solution: Use NBIA = kθ, I = kθ/NBA, Sᵢ = NBA/k, Sᵥ = NBA/kG, k_g = k/NBA, S = IgG/(I − Ig), and R = V/Ig − G.
Case Study 9instrument damage
Scenario: A moving coil galvanometer has N turns, coil area A, magnetic field B, galvanometer resistance G and torsional constant k. A current produces angular deflection θ.
Questions: find current, sensitivity, figure of merit or required shunt/series resistance.
Solution: Use NBIA = kθ, I = kθ/NBA, Sᵢ = NBA/k, Sᵥ = NBA/kG, k_g = k/NBA, S = IgG/(I − Ig), and R = V/Ig − G.
Case Study 10experimental current measurement
Scenario: A moving coil galvanometer has N turns, coil area A, magnetic field B, galvanometer resistance G and torsional constant k. A current produces angular deflection θ.
Questions: find current, sensitivity, figure of merit or required shunt/series resistance.
Solution: Use NBIA = kθ, I = kθ/NBA, Sᵢ = NBA/k, Sᵥ = NBA/kG, k_g = k/NBA, S = IgG/(I − Ig), and R = V/Ig − G.

B. NEET Questions

NEET MCQ 1A moving coil galvanometer works on
  1. heating effect
  2. torque on current carrying coil
  3. photoelectric effect
  4. induction only
Correct Answer: B
Difficulty: Medium
Concept Tested: Moving coil galvanometer principle, sensitivity, conversion and torque balance.
Detailed Explanation: A current carrying coil in magnetic field experiences torque.
Common Student Mistake: Do not confuse current sensitivity with figure of merit, and do not use non-radial torque formula in radial field.
NEET MCQ 2In a radial magnetic field, torque on coil is
  1. NBIA sinθ
  2. NBIA
  3. zero
  4. NBA/I
Correct Answer: B
Difficulty: Medium
Concept Tested: Moving coil galvanometer principle, sensitivity, conversion and torque balance.
Detailed Explanation: Area vector remains perpendicular to B, so sinα = 1.
Common Student Mistake: Do not confuse current sensitivity with figure of merit, and do not use non-radial torque formula in radial field.
NEET MCQ 3Current sensitivity of galvanometer is
  1. θ/I
  2. I/θ
  3. V/θ
  4. G/I
Correct Answer: A
Difficulty: Medium
Concept Tested: Moving coil galvanometer principle, sensitivity, conversion and torque balance.
Detailed Explanation: Sᵢ = θ/I = NBA/k.
Common Student Mistake: Do not confuse current sensitivity with figure of merit, and do not use non-radial torque formula in radial field.
NEET MCQ 4Voltage sensitivity is
  1. NBA/k
  2. NBA/kG
  3. k/NBA
  4. IgG
Correct Answer: B
Difficulty: Medium
Concept Tested: Moving coil galvanometer principle, sensitivity, conversion and torque balance.
Detailed Explanation: Sᵥ = θ/V = NBA/kG.
Common Student Mistake: Do not confuse current sensitivity with figure of merit, and do not use non-radial torque formula in radial field.
NEET MCQ 5Figure of merit is
  1. θ/I
  2. I/θ
  3. V/I
  4. IG
Correct Answer: B
Difficulty: Medium
Concept Tested: Moving coil galvanometer principle, sensitivity, conversion and torque balance.
Detailed Explanation: It is current required for one division deflection.
Common Student Mistake: Do not confuse current sensitivity with figure of merit, and do not use non-radial torque formula in radial field.
NEET MCQ 6For ammeter conversion, shunt is connected
  1. in series
  2. in parallel
  3. open circuit
  4. with scale only
Correct Answer: B
Difficulty: Medium
Concept Tested: Moving coil galvanometer principle, sensitivity, conversion and torque balance.
Detailed Explanation: Low resistance shunt bypasses most current.
Common Student Mistake: Do not confuse current sensitivity with figure of merit, and do not use non-radial torque formula in radial field.
NEET MCQ 7For voltmeter conversion, resistance is connected
  1. in parallel
  2. in series
  3. in short
  4. not needed
Correct Answer: B
Difficulty: Medium
Concept Tested: Moving coil galvanometer principle, sensitivity, conversion and torque balance.
Detailed Explanation: High resistance in series limits current.
Common Student Mistake: Do not confuse current sensitivity with figure of merit, and do not use non-radial torque formula in radial field.
NEET MCQ 8Soft iron core is used to
  1. decrease B
  2. increase and radialize B
  3. remove current
  4. increase friction
Correct Answer: B
Difficulty: Medium
Concept Tested: Moving coil galvanometer principle, sensitivity, conversion and torque balance.
Detailed Explanation: It strengthens field and helps make it radial.
Common Student Mistake: Do not confuse current sensitivity with figure of merit, and do not use non-radial torque formula in radial field.
NEET MCQ 9Phosphor bronze strip provides
  1. only heat
  2. restoring torque and current path
  3. magnetic shielding
  4. AC rectification
Correct Answer: B
Difficulty: Medium
Concept Tested: Moving coil galvanometer principle, sensitivity, conversion and torque balance.
Detailed Explanation: It supports coil, conducts current and provides torsion.
Common Student Mistake: Do not confuse current sensitivity with figure of merit, and do not use non-radial torque formula in radial field.
NEET MCQ 10The scale is linear because
  1. θ ∝ I
  2. θ ∝ I²
  3. θ independent of I
  4. B=0
Correct Answer: A
Difficulty: Medium
Concept Tested: Moving coil galvanometer principle, sensitivity, conversion and torque balance.
Detailed Explanation: From NBIA = kθ, θ = NBAI/k.
Common Student Mistake: Do not confuse current sensitivity with figure of merit, and do not use non-radial torque formula in radial field.
NEET MCQ 11A moving coil galvanometer works on
  1. heating effect
  2. torque on current carrying coil
  3. photoelectric effect
  4. induction only
Correct Answer: B
Difficulty: Medium
Concept Tested: Moving coil galvanometer principle, sensitivity, conversion and torque balance.
Detailed Explanation: A current carrying coil in magnetic field experiences torque.
Common Student Mistake: Do not confuse current sensitivity with figure of merit, and do not use non-radial torque formula in radial field.
NEET MCQ 12In a radial magnetic field, torque on coil is
  1. NBIA sinθ
  2. NBIA
  3. zero
  4. NBA/I
Correct Answer: B
Difficulty: Medium
Concept Tested: Moving coil galvanometer principle, sensitivity, conversion and torque balance.
Detailed Explanation: Area vector remains perpendicular to B, so sinα = 1.
Common Student Mistake: Do not confuse current sensitivity with figure of merit, and do not use non-radial torque formula in radial field.
NEET MCQ 13Current sensitivity of galvanometer is
  1. θ/I
  2. I/θ
  3. V/θ
  4. G/I
Correct Answer: A
Difficulty: Medium
Concept Tested: Moving coil galvanometer principle, sensitivity, conversion and torque balance.
Detailed Explanation: Sᵢ = θ/I = NBA/k.
Common Student Mistake: Do not confuse current sensitivity with figure of merit, and do not use non-radial torque formula in radial field.
NEET MCQ 14Voltage sensitivity is
  1. NBA/k
  2. NBA/kG
  3. k/NBA
  4. IgG
Correct Answer: B
Difficulty: Medium
Concept Tested: Moving coil galvanometer principle, sensitivity, conversion and torque balance.
Detailed Explanation: Sᵥ = θ/V = NBA/kG.
Common Student Mistake: Do not confuse current sensitivity with figure of merit, and do not use non-radial torque formula in radial field.
NEET MCQ 15Figure of merit is
  1. θ/I
  2. I/θ
  3. V/I
  4. IG
Correct Answer: B
Difficulty: Medium
Concept Tested: Moving coil galvanometer principle, sensitivity, conversion and torque balance.
Detailed Explanation: It is current required for one division deflection.
Common Student Mistake: Do not confuse current sensitivity with figure of merit, and do not use non-radial torque formula in radial field.
NEET MCQ 16For ammeter conversion, shunt is connected
  1. in series
  2. in parallel
  3. open circuit
  4. with scale only
Correct Answer: B
Difficulty: Medium
Concept Tested: Moving coil galvanometer principle, sensitivity, conversion and torque balance.
Detailed Explanation: Low resistance shunt bypasses most current.
Common Student Mistake: Do not confuse current sensitivity with figure of merit, and do not use non-radial torque formula in radial field.
NEET MCQ 17For voltmeter conversion, resistance is connected
  1. in parallel
  2. in series
  3. in short
  4. not needed
Correct Answer: B
Difficulty: Medium
Concept Tested: Moving coil galvanometer principle, sensitivity, conversion and torque balance.
Detailed Explanation: High resistance in series limits current.
Common Student Mistake: Do not confuse current sensitivity with figure of merit, and do not use non-radial torque formula in radial field.
NEET MCQ 18Soft iron core is used to
  1. decrease B
  2. increase and radialize B
  3. remove current
  4. increase friction
Correct Answer: B
Difficulty: Medium
Concept Tested: Moving coil galvanometer principle, sensitivity, conversion and torque balance.
Detailed Explanation: It strengthens field and helps make it radial.
Common Student Mistake: Do not confuse current sensitivity with figure of merit, and do not use non-radial torque formula in radial field.
NEET MCQ 19Phosphor bronze strip provides
  1. only heat
  2. restoring torque and current path
  3. magnetic shielding
  4. AC rectification
Correct Answer: B
Difficulty: Medium
Concept Tested: Moving coil galvanometer principle, sensitivity, conversion and torque balance.
Detailed Explanation: It supports coil, conducts current and provides torsion.
Common Student Mistake: Do not confuse current sensitivity with figure of merit, and do not use non-radial torque formula in radial field.
NEET MCQ 20The scale is linear because
  1. θ ∝ I
  2. θ ∝ I²
  3. θ independent of I
  4. B=0
Correct Answer: A
Difficulty: Medium
Concept Tested: Moving coil galvanometer principle, sensitivity, conversion and torque balance.
Detailed Explanation: From NBIA = kθ, θ = NBAI/k.
Common Student Mistake: Do not confuse current sensitivity with figure of merit, and do not use non-radial torque formula in radial field.
NEET MCQ 21A moving coil galvanometer works on
  1. heating effect
  2. torque on current carrying coil
  3. photoelectric effect
  4. induction only
Correct Answer: B
Difficulty: Medium
Concept Tested: Moving coil galvanometer principle, sensitivity, conversion and torque balance.
Detailed Explanation: A current carrying coil in magnetic field experiences torque.
Common Student Mistake: Do not confuse current sensitivity with figure of merit, and do not use non-radial torque formula in radial field.
NEET MCQ 22In a radial magnetic field, torque on coil is
  1. NBIA sinθ
  2. NBIA
  3. zero
  4. NBA/I
Correct Answer: B
Difficulty: Medium
Concept Tested: Moving coil galvanometer principle, sensitivity, conversion and torque balance.
Detailed Explanation: Area vector remains perpendicular to B, so sinα = 1.
Common Student Mistake: Do not confuse current sensitivity with figure of merit, and do not use non-radial torque formula in radial field.
NEET MCQ 23Current sensitivity of galvanometer is
  1. θ/I
  2. I/θ
  3. V/θ
  4. G/I
Correct Answer: A
Difficulty: Medium
Concept Tested: Moving coil galvanometer principle, sensitivity, conversion and torque balance.
Detailed Explanation: Sᵢ = θ/I = NBA/k.
Common Student Mistake: Do not confuse current sensitivity with figure of merit, and do not use non-radial torque formula in radial field.
NEET MCQ 24Voltage sensitivity is
  1. NBA/k
  2. NBA/kG
  3. k/NBA
  4. IgG
Correct Answer: B
Difficulty: Medium
Concept Tested: Moving coil galvanometer principle, sensitivity, conversion and torque balance.
Detailed Explanation: Sᵥ = θ/V = NBA/kG.
Common Student Mistake: Do not confuse current sensitivity with figure of merit, and do not use non-radial torque formula in radial field.
NEET MCQ 25Figure of merit is
  1. θ/I
  2. I/θ
  3. V/I
  4. IG
Correct Answer: B
Difficulty: Medium
Concept Tested: Moving coil galvanometer principle, sensitivity, conversion and torque balance.
Detailed Explanation: It is current required for one division deflection.
Common Student Mistake: Do not confuse current sensitivity with figure of merit, and do not use non-radial torque formula in radial field.
NEET MCQ 26For ammeter conversion, shunt is connected
  1. in series
  2. in parallel
  3. open circuit
  4. with scale only
Correct Answer: B
Difficulty: Medium
Concept Tested: Moving coil galvanometer principle, sensitivity, conversion and torque balance.
Detailed Explanation: Low resistance shunt bypasses most current.
Common Student Mistake: Do not confuse current sensitivity with figure of merit, and do not use non-radial torque formula in radial field.
NEET MCQ 27For voltmeter conversion, resistance is connected
  1. in parallel
  2. in series
  3. in short
  4. not needed
Correct Answer: B
Difficulty: Medium
Concept Tested: Moving coil galvanometer principle, sensitivity, conversion and torque balance.
Detailed Explanation: High resistance in series limits current.
Common Student Mistake: Do not confuse current sensitivity with figure of merit, and do not use non-radial torque formula in radial field.
NEET MCQ 28Soft iron core is used to
  1. decrease B
  2. increase and radialize B
  3. remove current
  4. increase friction
Correct Answer: B
Difficulty: Medium
Concept Tested: Moving coil galvanometer principle, sensitivity, conversion and torque balance.
Detailed Explanation: It strengthens field and helps make it radial.
Common Student Mistake: Do not confuse current sensitivity with figure of merit, and do not use non-radial torque formula in radial field.
NEET MCQ 29Phosphor bronze strip provides
  1. only heat
  2. restoring torque and current path
  3. magnetic shielding
  4. AC rectification
Correct Answer: B
Difficulty: Medium
Concept Tested: Moving coil galvanometer principle, sensitivity, conversion and torque balance.
Detailed Explanation: It supports coil, conducts current and provides torsion.
Common Student Mistake: Do not confuse current sensitivity with figure of merit, and do not use non-radial torque formula in radial field.
NEET MCQ 30The scale is linear because
  1. θ ∝ I
  2. θ ∝ I²
  3. θ independent of I
  4. B=0
Correct Answer: A
Difficulty: Medium
Concept Tested: Moving coil galvanometer principle, sensitivity, conversion and torque balance.
Detailed Explanation: From NBIA = kθ, θ = NBAI/k.
Common Student Mistake: Do not confuse current sensitivity with figure of merit, and do not use non-radial torque formula in radial field.
NEET MCQ 31A moving coil galvanometer works on
  1. heating effect
  2. torque on current carrying coil
  3. photoelectric effect
  4. induction only
Correct Answer: B
Difficulty: Medium
Concept Tested: Moving coil galvanometer principle, sensitivity, conversion and torque balance.
Detailed Explanation: A current carrying coil in magnetic field experiences torque.
Common Student Mistake: Do not confuse current sensitivity with figure of merit, and do not use non-radial torque formula in radial field.
NEET MCQ 32In a radial magnetic field, torque on coil is
  1. NBIA sinθ
  2. NBIA
  3. zero
  4. NBA/I
Correct Answer: B
Difficulty: Medium
Concept Tested: Moving coil galvanometer principle, sensitivity, conversion and torque balance.
Detailed Explanation: Area vector remains perpendicular to B, so sinα = 1.
Common Student Mistake: Do not confuse current sensitivity with figure of merit, and do not use non-radial torque formula in radial field.
NEET MCQ 33Current sensitivity of galvanometer is
  1. θ/I
  2. I/θ
  3. V/θ
  4. G/I
Correct Answer: A
Difficulty: Medium
Concept Tested: Moving coil galvanometer principle, sensitivity, conversion and torque balance.
Detailed Explanation: Sᵢ = θ/I = NBA/k.
Common Student Mistake: Do not confuse current sensitivity with figure of merit, and do not use non-radial torque formula in radial field.
NEET MCQ 34Voltage sensitivity is
  1. NBA/k
  2. NBA/kG
  3. k/NBA
  4. IgG
Correct Answer: B
Difficulty: Medium
Concept Tested: Moving coil galvanometer principle, sensitivity, conversion and torque balance.
Detailed Explanation: Sᵥ = θ/V = NBA/kG.
Common Student Mistake: Do not confuse current sensitivity with figure of merit, and do not use non-radial torque formula in radial field.
NEET MCQ 35Figure of merit is
  1. θ/I
  2. I/θ
  3. V/I
  4. IG
Correct Answer: B
Difficulty: Medium
Concept Tested: Moving coil galvanometer principle, sensitivity, conversion and torque balance.
Detailed Explanation: It is current required for one division deflection.
Common Student Mistake: Do not confuse current sensitivity with figure of merit, and do not use non-radial torque formula in radial field.
NEET MCQ 36For ammeter conversion, shunt is connected
  1. in series
  2. in parallel
  3. open circuit
  4. with scale only
Correct Answer: B
Difficulty: Medium
Concept Tested: Moving coil galvanometer principle, sensitivity, conversion and torque balance.
Detailed Explanation: Low resistance shunt bypasses most current.
Common Student Mistake: Do not confuse current sensitivity with figure of merit, and do not use non-radial torque formula in radial field.
NEET MCQ 37For voltmeter conversion, resistance is connected
  1. in parallel
  2. in series
  3. in short
  4. not needed
Correct Answer: B
Difficulty: Medium
Concept Tested: Moving coil galvanometer principle, sensitivity, conversion and torque balance.
Detailed Explanation: High resistance in series limits current.
Common Student Mistake: Do not confuse current sensitivity with figure of merit, and do not use non-radial torque formula in radial field.
NEET MCQ 38Soft iron core is used to
  1. decrease B
  2. increase and radialize B
  3. remove current
  4. increase friction
Correct Answer: B
Difficulty: Medium
Concept Tested: Moving coil galvanometer principle, sensitivity, conversion and torque balance.
Detailed Explanation: It strengthens field and helps make it radial.
Common Student Mistake: Do not confuse current sensitivity with figure of merit, and do not use non-radial torque formula in radial field.
NEET MCQ 39Phosphor bronze strip provides
  1. only heat
  2. restoring torque and current path
  3. magnetic shielding
  4. AC rectification
Correct Answer: B
Difficulty: Medium
Concept Tested: Moving coil galvanometer principle, sensitivity, conversion and torque balance.
Detailed Explanation: It supports coil, conducts current and provides torsion.
Common Student Mistake: Do not confuse current sensitivity with figure of merit, and do not use non-radial torque formula in radial field.
NEET MCQ 40The scale is linear because
  1. θ ∝ I
  2. θ ∝ I²
  3. θ independent of I
  4. B=0
Correct Answer: A
Difficulty: Medium
Concept Tested: Moving coil galvanometer principle, sensitivity, conversion and torque balance.
Detailed Explanation: From NBIA = kθ, θ = NBAI/k.
Common Student Mistake: Do not confuse current sensitivity with figure of merit, and do not use non-radial torque formula in radial field.
NEET MCQ 41A moving coil galvanometer works on
  1. heating effect
  2. torque on current carrying coil
  3. photoelectric effect
  4. induction only
Correct Answer: B
Difficulty: Medium
Concept Tested: Moving coil galvanometer principle, sensitivity, conversion and torque balance.
Detailed Explanation: A current carrying coil in magnetic field experiences torque.
Common Student Mistake: Do not confuse current sensitivity with figure of merit, and do not use non-radial torque formula in radial field.
NEET MCQ 42In a radial magnetic field, torque on coil is
  1. NBIA sinθ
  2. NBIA
  3. zero
  4. NBA/I
Correct Answer: B
Difficulty: Medium
Concept Tested: Moving coil galvanometer principle, sensitivity, conversion and torque balance.
Detailed Explanation: Area vector remains perpendicular to B, so sinα = 1.
Common Student Mistake: Do not confuse current sensitivity with figure of merit, and do not use non-radial torque formula in radial field.
NEET MCQ 43Current sensitivity of galvanometer is
  1. θ/I
  2. I/θ
  3. V/θ
  4. G/I
Correct Answer: A
Difficulty: Medium
Concept Tested: Moving coil galvanometer principle, sensitivity, conversion and torque balance.
Detailed Explanation: Sᵢ = θ/I = NBA/k.
Common Student Mistake: Do not confuse current sensitivity with figure of merit, and do not use non-radial torque formula in radial field.
NEET MCQ 44Voltage sensitivity is
  1. NBA/k
  2. NBA/kG
  3. k/NBA
  4. IgG
Correct Answer: B
Difficulty: Medium
Concept Tested: Moving coil galvanometer principle, sensitivity, conversion and torque balance.
Detailed Explanation: Sᵥ = θ/V = NBA/kG.
Common Student Mistake: Do not confuse current sensitivity with figure of merit, and do not use non-radial torque formula in radial field.
NEET MCQ 45Figure of merit is
  1. θ/I
  2. I/θ
  3. V/I
  4. IG
Correct Answer: B
Difficulty: Medium
Concept Tested: Moving coil galvanometer principle, sensitivity, conversion and torque balance.
Detailed Explanation: It is current required for one division deflection.
Common Student Mistake: Do not confuse current sensitivity with figure of merit, and do not use non-radial torque formula in radial field.
NEET MCQ 46For ammeter conversion, shunt is connected
  1. in series
  2. in parallel
  3. open circuit
  4. with scale only
Correct Answer: B
Difficulty: Medium
Concept Tested: Moving coil galvanometer principle, sensitivity, conversion and torque balance.
Detailed Explanation: Low resistance shunt bypasses most current.
Common Student Mistake: Do not confuse current sensitivity with figure of merit, and do not use non-radial torque formula in radial field.
NEET MCQ 47For voltmeter conversion, resistance is connected
  1. in parallel
  2. in series
  3. in short
  4. not needed
Correct Answer: B
Difficulty: Medium
Concept Tested: Moving coil galvanometer principle, sensitivity, conversion and torque balance.
Detailed Explanation: High resistance in series limits current.
Common Student Mistake: Do not confuse current sensitivity with figure of merit, and do not use non-radial torque formula in radial field.
NEET MCQ 48Soft iron core is used to
  1. decrease B
  2. increase and radialize B
  3. remove current
  4. increase friction
Correct Answer: B
Difficulty: Medium
Concept Tested: Moving coil galvanometer principle, sensitivity, conversion and torque balance.
Detailed Explanation: It strengthens field and helps make it radial.
Common Student Mistake: Do not confuse current sensitivity with figure of merit, and do not use non-radial torque formula in radial field.
NEET MCQ 49Phosphor bronze strip provides
  1. only heat
  2. restoring torque and current path
  3. magnetic shielding
  4. AC rectification
Correct Answer: B
Difficulty: Medium
Concept Tested: Moving coil galvanometer principle, sensitivity, conversion and torque balance.
Detailed Explanation: It supports coil, conducts current and provides torsion.
Common Student Mistake: Do not confuse current sensitivity with figure of merit, and do not use non-radial torque formula in radial field.
NEET MCQ 50The scale is linear because
  1. θ ∝ I
  2. θ ∝ I²
  3. θ independent of I
  4. B=0
Correct Answer: A
Difficulty: Medium
Concept Tested: Moving coil galvanometer principle, sensitivity, conversion and torque balance.
Detailed Explanation: From NBIA = kθ, θ = NBAI/k.
Common Student Mistake: Do not confuse current sensitivity with figure of merit, and do not use non-radial torque formula in radial field.
NEET MCQ 51A moving coil galvanometer works on
  1. heating effect
  2. torque on current carrying coil
  3. photoelectric effect
  4. induction only
Correct Answer: B
Difficulty: Medium
Concept Tested: Moving coil galvanometer principle, sensitivity, conversion and torque balance.
Detailed Explanation: A current carrying coil in magnetic field experiences torque.
Common Student Mistake: Do not confuse current sensitivity with figure of merit, and do not use non-radial torque formula in radial field.
NEET MCQ 52In a radial magnetic field, torque on coil is
  1. NBIA sinθ
  2. NBIA
  3. zero
  4. NBA/I
Correct Answer: B
Difficulty: Medium
Concept Tested: Moving coil galvanometer principle, sensitivity, conversion and torque balance.
Detailed Explanation: Area vector remains perpendicular to B, so sinα = 1.
Common Student Mistake: Do not confuse current sensitivity with figure of merit, and do not use non-radial torque formula in radial field.
NEET MCQ 53Current sensitivity of galvanometer is
  1. θ/I
  2. I/θ
  3. V/θ
  4. G/I
Correct Answer: A
Difficulty: Medium
Concept Tested: Moving coil galvanometer principle, sensitivity, conversion and torque balance.
Detailed Explanation: Sᵢ = θ/I = NBA/k.
Common Student Mistake: Do not confuse current sensitivity with figure of merit, and do not use non-radial torque formula in radial field.
NEET MCQ 54Voltage sensitivity is
  1. NBA/k
  2. NBA/kG
  3. k/NBA
  4. IgG
Correct Answer: B
Difficulty: Medium
Concept Tested: Moving coil galvanometer principle, sensitivity, conversion and torque balance.
Detailed Explanation: Sᵥ = θ/V = NBA/kG.
Common Student Mistake: Do not confuse current sensitivity with figure of merit, and do not use non-radial torque formula in radial field.
NEET MCQ 55Figure of merit is
  1. θ/I
  2. I/θ
  3. V/I
  4. IG
Correct Answer: B
Difficulty: Medium
Concept Tested: Moving coil galvanometer principle, sensitivity, conversion and torque balance.
Detailed Explanation: It is current required for one division deflection.
Common Student Mistake: Do not confuse current sensitivity with figure of merit, and do not use non-radial torque formula in radial field.
NEET MCQ 56For ammeter conversion, shunt is connected
  1. in series
  2. in parallel
  3. open circuit
  4. with scale only
Correct Answer: B
Difficulty: Medium
Concept Tested: Moving coil galvanometer principle, sensitivity, conversion and torque balance.
Detailed Explanation: Low resistance shunt bypasses most current.
Common Student Mistake: Do not confuse current sensitivity with figure of merit, and do not use non-radial torque formula in radial field.
NEET MCQ 57For voltmeter conversion, resistance is connected
  1. in parallel
  2. in series
  3. in short
  4. not needed
Correct Answer: B
Difficulty: Medium
Concept Tested: Moving coil galvanometer principle, sensitivity, conversion and torque balance.
Detailed Explanation: High resistance in series limits current.
Common Student Mistake: Do not confuse current sensitivity with figure of merit, and do not use non-radial torque formula in radial field.
NEET MCQ 58Soft iron core is used to
  1. decrease B
  2. increase and radialize B
  3. remove current
  4. increase friction
Correct Answer: B
Difficulty: Medium
Concept Tested: Moving coil galvanometer principle, sensitivity, conversion and torque balance.
Detailed Explanation: It strengthens field and helps make it radial.
Common Student Mistake: Do not confuse current sensitivity with figure of merit, and do not use non-radial torque formula in radial field.
NEET MCQ 59Phosphor bronze strip provides
  1. only heat
  2. restoring torque and current path
  3. magnetic shielding
  4. AC rectification
Correct Answer: B
Difficulty: Medium
Concept Tested: Moving coil galvanometer principle, sensitivity, conversion and torque balance.
Detailed Explanation: It supports coil, conducts current and provides torsion.
Common Student Mistake: Do not confuse current sensitivity with figure of merit, and do not use non-radial torque formula in radial field.
NEET MCQ 60The scale is linear because
  1. θ ∝ I
  2. θ ∝ I²
  3. θ independent of I
  4. B=0
Correct Answer: A
Difficulty: Medium
Concept Tested: Moving coil galvanometer principle, sensitivity, conversion and torque balance.
Detailed Explanation: From NBIA = kθ, θ = NBAI/k.
Common Student Mistake: Do not confuse current sensitivity with figure of merit, and do not use non-radial torque formula in radial field.
NEET MCQ 61A moving coil galvanometer works on
  1. heating effect
  2. torque on current carrying coil
  3. photoelectric effect
  4. induction only
Correct Answer: B
Difficulty: Medium
Concept Tested: Moving coil galvanometer principle, sensitivity, conversion and torque balance.
Detailed Explanation: A current carrying coil in magnetic field experiences torque.
Common Student Mistake: Do not confuse current sensitivity with figure of merit, and do not use non-radial torque formula in radial field.
NEET MCQ 62In a radial magnetic field, torque on coil is
  1. NBIA sinθ
  2. NBIA
  3. zero
  4. NBA/I
Correct Answer: B
Difficulty: Medium
Concept Tested: Moving coil galvanometer principle, sensitivity, conversion and torque balance.
Detailed Explanation: Area vector remains perpendicular to B, so sinα = 1.
Common Student Mistake: Do not confuse current sensitivity with figure of merit, and do not use non-radial torque formula in radial field.
NEET MCQ 63Current sensitivity of galvanometer is
  1. θ/I
  2. I/θ
  3. V/θ
  4. G/I
Correct Answer: A
Difficulty: Medium
Concept Tested: Moving coil galvanometer principle, sensitivity, conversion and torque balance.
Detailed Explanation: Sᵢ = θ/I = NBA/k.
Common Student Mistake: Do not confuse current sensitivity with figure of merit, and do not use non-radial torque formula in radial field.
NEET MCQ 64Voltage sensitivity is
  1. NBA/k
  2. NBA/kG
  3. k/NBA
  4. IgG
Correct Answer: B
Difficulty: Medium
Concept Tested: Moving coil galvanometer principle, sensitivity, conversion and torque balance.
Detailed Explanation: Sᵥ = θ/V = NBA/kG.
Common Student Mistake: Do not confuse current sensitivity with figure of merit, and do not use non-radial torque formula in radial field.
NEET MCQ 65Figure of merit is
  1. θ/I
  2. I/θ
  3. V/I
  4. IG
Correct Answer: B
Difficulty: Medium
Concept Tested: Moving coil galvanometer principle, sensitivity, conversion and torque balance.
Detailed Explanation: It is current required for one division deflection.
Common Student Mistake: Do not confuse current sensitivity with figure of merit, and do not use non-radial torque formula in radial field.
NEET MCQ 66For ammeter conversion, shunt is connected
  1. in series
  2. in parallel
  3. open circuit
  4. with scale only
Correct Answer: B
Difficulty: Medium
Concept Tested: Moving coil galvanometer principle, sensitivity, conversion and torque balance.
Detailed Explanation: Low resistance shunt bypasses most current.
Common Student Mistake: Do not confuse current sensitivity with figure of merit, and do not use non-radial torque formula in radial field.
NEET MCQ 67For voltmeter conversion, resistance is connected
  1. in parallel
  2. in series
  3. in short
  4. not needed
Correct Answer: B
Difficulty: Medium
Concept Tested: Moving coil galvanometer principle, sensitivity, conversion and torque balance.
Detailed Explanation: High resistance in series limits current.
Common Student Mistake: Do not confuse current sensitivity with figure of merit, and do not use non-radial torque formula in radial field.
NEET MCQ 68Soft iron core is used to
  1. decrease B
  2. increase and radialize B
  3. remove current
  4. increase friction
Correct Answer: B
Difficulty: Medium
Concept Tested: Moving coil galvanometer principle, sensitivity, conversion and torque balance.
Detailed Explanation: It strengthens field and helps make it radial.
Common Student Mistake: Do not confuse current sensitivity with figure of merit, and do not use non-radial torque formula in radial field.
NEET MCQ 69Phosphor bronze strip provides
  1. only heat
  2. restoring torque and current path
  3. magnetic shielding
  4. AC rectification
Correct Answer: B
Difficulty: Medium
Concept Tested: Moving coil galvanometer principle, sensitivity, conversion and torque balance.
Detailed Explanation: It supports coil, conducts current and provides torsion.
Common Student Mistake: Do not confuse current sensitivity with figure of merit, and do not use non-radial torque formula in radial field.
NEET MCQ 70The scale is linear because
  1. θ ∝ I
  2. θ ∝ I²
  3. θ independent of I
  4. B=0
Correct Answer: A
Difficulty: Medium
Concept Tested: Moving coil galvanometer principle, sensitivity, conversion and torque balance.
Detailed Explanation: From NBIA = kθ, θ = NBAI/k.
Common Student Mistake: Do not confuse current sensitivity with figure of merit, and do not use non-radial torque formula in radial field.
NEET MCQ 71A moving coil galvanometer works on
  1. heating effect
  2. torque on current carrying coil
  3. photoelectric effect
  4. induction only
Correct Answer: B
Difficulty: Medium
Concept Tested: Moving coil galvanometer principle, sensitivity, conversion and torque balance.
Detailed Explanation: A current carrying coil in magnetic field experiences torque.
Common Student Mistake: Do not confuse current sensitivity with figure of merit, and do not use non-radial torque formula in radial field.
NEET MCQ 72In a radial magnetic field, torque on coil is
  1. NBIA sinθ
  2. NBIA
  3. zero
  4. NBA/I
Correct Answer: B
Difficulty: Medium
Concept Tested: Moving coil galvanometer principle, sensitivity, conversion and torque balance.
Detailed Explanation: Area vector remains perpendicular to B, so sinα = 1.
Common Student Mistake: Do not confuse current sensitivity with figure of merit, and do not use non-radial torque formula in radial field.
NEET MCQ 73Current sensitivity of galvanometer is
  1. θ/I
  2. I/θ
  3. V/θ
  4. G/I
Correct Answer: A
Difficulty: Medium
Concept Tested: Moving coil galvanometer principle, sensitivity, conversion and torque balance.
Detailed Explanation: Sᵢ = θ/I = NBA/k.
Common Student Mistake: Do not confuse current sensitivity with figure of merit, and do not use non-radial torque formula in radial field.
NEET MCQ 74Voltage sensitivity is
  1. NBA/k
  2. NBA/kG
  3. k/NBA
  4. IgG
Correct Answer: B
Difficulty: Medium
Concept Tested: Moving coil galvanometer principle, sensitivity, conversion and torque balance.
Detailed Explanation: Sᵥ = θ/V = NBA/kG.
Common Student Mistake: Do not confuse current sensitivity with figure of merit, and do not use non-radial torque formula in radial field.
NEET MCQ 75Figure of merit is
  1. θ/I
  2. I/θ
  3. V/I
  4. IG
Correct Answer: B
Difficulty: Medium
Concept Tested: Moving coil galvanometer principle, sensitivity, conversion and torque balance.
Detailed Explanation: It is current required for one division deflection.
Common Student Mistake: Do not confuse current sensitivity with figure of merit, and do not use non-radial torque formula in radial field.

C. JEE Main Questions

JEE Main MCQ 1Figure of merit is Use a variation with N=40, B=0.1 T, A=1×10⁻⁴ m², k=1×10⁻⁶ N m rad⁻¹ or G=10 Ω.
  1. θ/I
  2. I/θ
  3. V/I
  4. IG
Correct Answer: B
Difficulty: Difficult
Concept Tested: Moving coil galvanometer principle, sensitivity, conversion and torque balance. Use a variation with N=40, B=0.1 T, A=1×10⁻⁴ m², k=1×10⁻⁶ N m rad⁻¹ or G=10 Ω.
Detailed Explanation: It is current required for one division deflection.
Common Student Mistake: Do not confuse current sensitivity with figure of merit, and do not use non-radial torque formula in radial field.
JEE Main MCQ 2For ammeter conversion, shunt is connected Use a variation with N=60, B=0.2 T, A=2×10⁻⁴ m², k=2×10⁻⁶ N m rad⁻¹ or G=20 Ω.
  1. in series
  2. in parallel
  3. open circuit
  4. with scale only
Correct Answer: B
Difficulty: Difficult
Concept Tested: Moving coil galvanometer principle, sensitivity, conversion and torque balance. Use a variation with N=60, B=0.2 T, A=2×10⁻⁴ m², k=2×10⁻⁶ N m rad⁻¹ or G=20 Ω.
Detailed Explanation: Low resistance shunt bypasses most current.
Common Student Mistake: Do not confuse current sensitivity with figure of merit, and do not use non-radial torque formula in radial field.
JEE Main MCQ 3For voltmeter conversion, resistance is connected Use a variation with N=80, B=0.3 T, A=3×10⁻⁴ m², k=3×10⁻⁶ N m rad⁻¹ or G=30 Ω.
  1. in parallel
  2. in series
  3. in short
  4. not needed
Correct Answer: B
Difficulty: Difficult
Concept Tested: Moving coil galvanometer principle, sensitivity, conversion and torque balance. Use a variation with N=80, B=0.3 T, A=3×10⁻⁴ m², k=3×10⁻⁶ N m rad⁻¹ or G=30 Ω.
Detailed Explanation: High resistance in series limits current.
Common Student Mistake: Do not confuse current sensitivity with figure of merit, and do not use non-radial torque formula in radial field.
JEE Main MCQ 4Soft iron core is used to Use a variation with N=100, B=0.4 T, A=4×10⁻⁴ m², k=4×10⁻⁶ N m rad⁻¹ or G=40 Ω.
  1. decrease B
  2. increase and radialize B
  3. remove current
  4. increase friction
Correct Answer: B
Difficulty: Difficult
Concept Tested: Moving coil galvanometer principle, sensitivity, conversion and torque balance. Use a variation with N=100, B=0.4 T, A=4×10⁻⁴ m², k=4×10⁻⁶ N m rad⁻¹ or G=40 Ω.
Detailed Explanation: It strengthens field and helps make it radial.
Common Student Mistake: Do not confuse current sensitivity with figure of merit, and do not use non-radial torque formula in radial field.
JEE Main MCQ 5Phosphor bronze strip provides Use a variation with N=120, B=0.5 T, A=5×10⁻⁴ m², k=1×10⁻⁶ N m rad⁻¹ or G=50 Ω.
  1. only heat
  2. restoring torque and current path
  3. magnetic shielding
  4. AC rectification
Correct Answer: B
Difficulty: Difficult
Concept Tested: Moving coil galvanometer principle, sensitivity, conversion and torque balance. Use a variation with N=120, B=0.5 T, A=5×10⁻⁴ m², k=1×10⁻⁶ N m rad⁻¹ or G=50 Ω.
Detailed Explanation: It supports coil, conducts current and provides torsion.
Common Student Mistake: Do not confuse current sensitivity with figure of merit, and do not use non-radial torque formula in radial field.
JEE Main MCQ 6The scale is linear because Use a variation with N=40, B=0.1 T, A=6×10⁻⁴ m², k=2×10⁻⁶ N m rad⁻¹ or G=10 Ω.
  1. θ ∝ I
  2. θ ∝ I²
  3. θ independent of I
  4. B=0
Correct Answer: A
Difficulty: Difficult
Concept Tested: Moving coil galvanometer principle, sensitivity, conversion and torque balance. Use a variation with N=40, B=0.1 T, A=6×10⁻⁴ m², k=2×10⁻⁶ N m rad⁻¹ or G=10 Ω.
Detailed Explanation: From NBIA = kθ, θ = NBAI/k.
Common Student Mistake: Do not confuse current sensitivity with figure of merit, and do not use non-radial torque formula in radial field.
JEE Main MCQ 7A moving coil galvanometer works on Use a variation with N=60, B=0.2 T, A=1×10⁻⁴ m², k=3×10⁻⁶ N m rad⁻¹ or G=20 Ω.
  1. heating effect
  2. torque on current carrying coil
  3. photoelectric effect
  4. induction only
Correct Answer: B
Difficulty: Difficult
Concept Tested: Moving coil galvanometer principle, sensitivity, conversion and torque balance. Use a variation with N=60, B=0.2 T, A=1×10⁻⁴ m², k=3×10⁻⁶ N m rad⁻¹ or G=20 Ω.
Detailed Explanation: A current carrying coil in magnetic field experiences torque.
Common Student Mistake: Do not confuse current sensitivity with figure of merit, and do not use non-radial torque formula in radial field.
JEE Main MCQ 8In a radial magnetic field, torque on coil is Use a variation with N=80, B=0.3 T, A=2×10⁻⁴ m², k=4×10⁻⁶ N m rad⁻¹ or G=30 Ω.
  1. NBIA sinθ
  2. NBIA
  3. zero
  4. NBA/I
Correct Answer: B
Difficulty: Difficult
Concept Tested: Moving coil galvanometer principle, sensitivity, conversion and torque balance. Use a variation with N=80, B=0.3 T, A=2×10⁻⁴ m², k=4×10⁻⁶ N m rad⁻¹ or G=30 Ω.
Detailed Explanation: Area vector remains perpendicular to B, so sinα = 1.
Common Student Mistake: Do not confuse current sensitivity with figure of merit, and do not use non-radial torque formula in radial field.
JEE Main MCQ 9Current sensitivity of galvanometer is Use a variation with N=100, B=0.4 T, A=3×10⁻⁴ m², k=1×10⁻⁶ N m rad⁻¹ or G=40 Ω.
  1. θ/I
  2. I/θ
  3. V/θ
  4. G/I
Correct Answer: A
Difficulty: Difficult
Concept Tested: Moving coil galvanometer principle, sensitivity, conversion and torque balance. Use a variation with N=100, B=0.4 T, A=3×10⁻⁴ m², k=1×10⁻⁶ N m rad⁻¹ or G=40 Ω.
Detailed Explanation: Sᵢ = θ/I = NBA/k.
Common Student Mistake: Do not confuse current sensitivity with figure of merit, and do not use non-radial torque formula in radial field.
JEE Main MCQ 10Voltage sensitivity is Use a variation with N=120, B=0.5 T, A=4×10⁻⁴ m², k=2×10⁻⁶ N m rad⁻¹ or G=50 Ω.
  1. NBA/k
  2. NBA/kG
  3. k/NBA
  4. IgG
Correct Answer: B
Difficulty: Difficult
Concept Tested: Moving coil galvanometer principle, sensitivity, conversion and torque balance. Use a variation with N=120, B=0.5 T, A=4×10⁻⁴ m², k=2×10⁻⁶ N m rad⁻¹ or G=50 Ω.
Detailed Explanation: Sᵥ = θ/V = NBA/kG.
Common Student Mistake: Do not confuse current sensitivity with figure of merit, and do not use non-radial torque formula in radial field.
JEE Main MCQ 11Figure of merit is Use a variation with N=40, B=0.1 T, A=5×10⁻⁴ m², k=3×10⁻⁶ N m rad⁻¹ or G=10 Ω.
  1. θ/I
  2. I/θ
  3. V/I
  4. IG
Correct Answer: B
Difficulty: Difficult
Concept Tested: Moving coil galvanometer principle, sensitivity, conversion and torque balance. Use a variation with N=40, B=0.1 T, A=5×10⁻⁴ m², k=3×10⁻⁶ N m rad⁻¹ or G=10 Ω.
Detailed Explanation: It is current required for one division deflection.
Common Student Mistake: Do not confuse current sensitivity with figure of merit, and do not use non-radial torque formula in radial field.
JEE Main MCQ 12For ammeter conversion, shunt is connected Use a variation with N=60, B=0.2 T, A=6×10⁻⁴ m², k=4×10⁻⁶ N m rad⁻¹ or G=20 Ω.
  1. in series
  2. in parallel
  3. open circuit
  4. with scale only
Correct Answer: B
Difficulty: Difficult
Concept Tested: Moving coil galvanometer principle, sensitivity, conversion and torque balance. Use a variation with N=60, B=0.2 T, A=6×10⁻⁴ m², k=4×10⁻⁶ N m rad⁻¹ or G=20 Ω.
Detailed Explanation: Low resistance shunt bypasses most current.
Common Student Mistake: Do not confuse current sensitivity with figure of merit, and do not use non-radial torque formula in radial field.
JEE Main MCQ 13For voltmeter conversion, resistance is connected Use a variation with N=80, B=0.3 T, A=1×10⁻⁴ m², k=1×10⁻⁶ N m rad⁻¹ or G=30 Ω.
  1. in parallel
  2. in series
  3. in short
  4. not needed
Correct Answer: B
Difficulty: Difficult
Concept Tested: Moving coil galvanometer principle, sensitivity, conversion and torque balance. Use a variation with N=80, B=0.3 T, A=1×10⁻⁴ m², k=1×10⁻⁶ N m rad⁻¹ or G=30 Ω.
Detailed Explanation: High resistance in series limits current.
Common Student Mistake: Do not confuse current sensitivity with figure of merit, and do not use non-radial torque formula in radial field.
JEE Main MCQ 14Soft iron core is used to Use a variation with N=100, B=0.4 T, A=2×10⁻⁴ m², k=2×10⁻⁶ N m rad⁻¹ or G=40 Ω.
  1. decrease B
  2. increase and radialize B
  3. remove current
  4. increase friction
Correct Answer: B
Difficulty: Difficult
Concept Tested: Moving coil galvanometer principle, sensitivity, conversion and torque balance. Use a variation with N=100, B=0.4 T, A=2×10⁻⁴ m², k=2×10⁻⁶ N m rad⁻¹ or G=40 Ω.
Detailed Explanation: It strengthens field and helps make it radial.
Common Student Mistake: Do not confuse current sensitivity with figure of merit, and do not use non-radial torque formula in radial field.
JEE Main MCQ 15Phosphor bronze strip provides Use a variation with N=120, B=0.5 T, A=3×10⁻⁴ m², k=3×10⁻⁶ N m rad⁻¹ or G=50 Ω.
  1. only heat
  2. restoring torque and current path
  3. magnetic shielding
  4. AC rectification
Correct Answer: B
Difficulty: Difficult
Concept Tested: Moving coil galvanometer principle, sensitivity, conversion and torque balance. Use a variation with N=120, B=0.5 T, A=3×10⁻⁴ m², k=3×10⁻⁶ N m rad⁻¹ or G=50 Ω.
Detailed Explanation: It supports coil, conducts current and provides torsion.
Common Student Mistake: Do not confuse current sensitivity with figure of merit, and do not use non-radial torque formula in radial field.
JEE Main MCQ 16The scale is linear because Use a variation with N=40, B=0.1 T, A=4×10⁻⁴ m², k=4×10⁻⁶ N m rad⁻¹ or G=10 Ω.
  1. θ ∝ I
  2. θ ∝ I²
  3. θ independent of I
  4. B=0
Correct Answer: A
Difficulty: Difficult
Concept Tested: Moving coil galvanometer principle, sensitivity, conversion and torque balance. Use a variation with N=40, B=0.1 T, A=4×10⁻⁴ m², k=4×10⁻⁶ N m rad⁻¹ or G=10 Ω.
Detailed Explanation: From NBIA = kθ, θ = NBAI/k.
Common Student Mistake: Do not confuse current sensitivity with figure of merit, and do not use non-radial torque formula in radial field.
JEE Main MCQ 17A moving coil galvanometer works on Use a variation with N=60, B=0.2 T, A=5×10⁻⁴ m², k=1×10⁻⁶ N m rad⁻¹ or G=20 Ω.
  1. heating effect
  2. torque on current carrying coil
  3. photoelectric effect
  4. induction only
Correct Answer: B
Difficulty: Difficult
Concept Tested: Moving coil galvanometer principle, sensitivity, conversion and torque balance. Use a variation with N=60, B=0.2 T, A=5×10⁻⁴ m², k=1×10⁻⁶ N m rad⁻¹ or G=20 Ω.
Detailed Explanation: A current carrying coil in magnetic field experiences torque.
Common Student Mistake: Do not confuse current sensitivity with figure of merit, and do not use non-radial torque formula in radial field.
JEE Main MCQ 18In a radial magnetic field, torque on coil is Use a variation with N=80, B=0.3 T, A=6×10⁻⁴ m², k=2×10⁻⁶ N m rad⁻¹ or G=30 Ω.
  1. NBIA sinθ
  2. NBIA
  3. zero
  4. NBA/I
Correct Answer: B
Difficulty: Difficult
Concept Tested: Moving coil galvanometer principle, sensitivity, conversion and torque balance. Use a variation with N=80, B=0.3 T, A=6×10⁻⁴ m², k=2×10⁻⁶ N m rad⁻¹ or G=30 Ω.
Detailed Explanation: Area vector remains perpendicular to B, so sinα = 1.
Common Student Mistake: Do not confuse current sensitivity with figure of merit, and do not use non-radial torque formula in radial field.
JEE Main MCQ 19Current sensitivity of galvanometer is Use a variation with N=100, B=0.4 T, A=1×10⁻⁴ m², k=3×10⁻⁶ N m rad⁻¹ or G=40 Ω.
  1. θ/I
  2. I/θ
  3. V/θ
  4. G/I
Correct Answer: A
Difficulty: Difficult
Concept Tested: Moving coil galvanometer principle, sensitivity, conversion and torque balance. Use a variation with N=100, B=0.4 T, A=1×10⁻⁴ m², k=3×10⁻⁶ N m rad⁻¹ or G=40 Ω.
Detailed Explanation: Sᵢ = θ/I = NBA/k.
Common Student Mistake: Do not confuse current sensitivity with figure of merit, and do not use non-radial torque formula in radial field.
JEE Main MCQ 20Voltage sensitivity is Use a variation with N=120, B=0.5 T, A=2×10⁻⁴ m², k=4×10⁻⁶ N m rad⁻¹ or G=50 Ω.
  1. NBA/k
  2. NBA/kG
  3. k/NBA
  4. IgG
Correct Answer: B
Difficulty: Difficult
Concept Tested: Moving coil galvanometer principle, sensitivity, conversion and torque balance. Use a variation with N=120, B=0.5 T, A=2×10⁻⁴ m², k=4×10⁻⁶ N m rad⁻¹ or G=50 Ω.
Detailed Explanation: Sᵥ = θ/V = NBA/kG.
Common Student Mistake: Do not confuse current sensitivity with figure of merit, and do not use non-radial torque formula in radial field.
JEE Main MCQ 21Figure of merit is Use a variation with N=40, B=0.1 T, A=3×10⁻⁴ m², k=1×10⁻⁶ N m rad⁻¹ or G=10 Ω.
  1. θ/I
  2. I/θ
  3. V/I
  4. IG
Correct Answer: B
Difficulty: Difficult
Concept Tested: Moving coil galvanometer principle, sensitivity, conversion and torque balance. Use a variation with N=40, B=0.1 T, A=3×10⁻⁴ m², k=1×10⁻⁶ N m rad⁻¹ or G=10 Ω.
Detailed Explanation: It is current required for one division deflection.
Common Student Mistake: Do not confuse current sensitivity with figure of merit, and do not use non-radial torque formula in radial field.
JEE Main MCQ 22For ammeter conversion, shunt is connected Use a variation with N=60, B=0.2 T, A=4×10⁻⁴ m², k=2×10⁻⁶ N m rad⁻¹ or G=20 Ω.
  1. in series
  2. in parallel
  3. open circuit
  4. with scale only
Correct Answer: B
Difficulty: Difficult
Concept Tested: Moving coil galvanometer principle, sensitivity, conversion and torque balance. Use a variation with N=60, B=0.2 T, A=4×10⁻⁴ m², k=2×10⁻⁶ N m rad⁻¹ or G=20 Ω.
Detailed Explanation: Low resistance shunt bypasses most current.
Common Student Mistake: Do not confuse current sensitivity with figure of merit, and do not use non-radial torque formula in radial field.
JEE Main MCQ 23For voltmeter conversion, resistance is connected Use a variation with N=80, B=0.3 T, A=5×10⁻⁴ m², k=3×10⁻⁶ N m rad⁻¹ or G=30 Ω.
  1. in parallel
  2. in series
  3. in short
  4. not needed
Correct Answer: B
Difficulty: Difficult
Concept Tested: Moving coil galvanometer principle, sensitivity, conversion and torque balance. Use a variation with N=80, B=0.3 T, A=5×10⁻⁴ m², k=3×10⁻⁶ N m rad⁻¹ or G=30 Ω.
Detailed Explanation: High resistance in series limits current.
Common Student Mistake: Do not confuse current sensitivity with figure of merit, and do not use non-radial torque formula in radial field.
JEE Main MCQ 24Soft iron core is used to Use a variation with N=100, B=0.4 T, A=6×10⁻⁴ m², k=4×10⁻⁶ N m rad⁻¹ or G=40 Ω.
  1. decrease B
  2. increase and radialize B
  3. remove current
  4. increase friction
Correct Answer: B
Difficulty: Difficult
Concept Tested: Moving coil galvanometer principle, sensitivity, conversion and torque balance. Use a variation with N=100, B=0.4 T, A=6×10⁻⁴ m², k=4×10⁻⁶ N m rad⁻¹ or G=40 Ω.
Detailed Explanation: It strengthens field and helps make it radial.
Common Student Mistake: Do not confuse current sensitivity with figure of merit, and do not use non-radial torque formula in radial field.
JEE Main MCQ 25Phosphor bronze strip provides Use a variation with N=120, B=0.5 T, A=1×10⁻⁴ m², k=1×10⁻⁶ N m rad⁻¹ or G=50 Ω.
  1. only heat
  2. restoring torque and current path
  3. magnetic shielding
  4. AC rectification
Correct Answer: B
Difficulty: Difficult
Concept Tested: Moving coil galvanometer principle, sensitivity, conversion and torque balance. Use a variation with N=120, B=0.5 T, A=1×10⁻⁴ m², k=1×10⁻⁶ N m rad⁻¹ or G=50 Ω.
Detailed Explanation: It supports coil, conducts current and provides torsion.
Common Student Mistake: Do not confuse current sensitivity with figure of merit, and do not use non-radial torque formula in radial field.
JEE Main MCQ 26The scale is linear because Use a variation with N=40, B=0.1 T, A=2×10⁻⁴ m², k=2×10⁻⁶ N m rad⁻¹ or G=10 Ω.
  1. θ ∝ I
  2. θ ∝ I²
  3. θ independent of I
  4. B=0
Correct Answer: A
Difficulty: Difficult
Concept Tested: Moving coil galvanometer principle, sensitivity, conversion and torque balance. Use a variation with N=40, B=0.1 T, A=2×10⁻⁴ m², k=2×10⁻⁶ N m rad⁻¹ or G=10 Ω.
Detailed Explanation: From NBIA = kθ, θ = NBAI/k.
Common Student Mistake: Do not confuse current sensitivity with figure of merit, and do not use non-radial torque formula in radial field.
JEE Main MCQ 27A moving coil galvanometer works on Use a variation with N=60, B=0.2 T, A=3×10⁻⁴ m², k=3×10⁻⁶ N m rad⁻¹ or G=20 Ω.
  1. heating effect
  2. torque on current carrying coil
  3. photoelectric effect
  4. induction only
Correct Answer: B
Difficulty: Difficult
Concept Tested: Moving coil galvanometer principle, sensitivity, conversion and torque balance. Use a variation with N=60, B=0.2 T, A=3×10⁻⁴ m², k=3×10⁻⁶ N m rad⁻¹ or G=20 Ω.
Detailed Explanation: A current carrying coil in magnetic field experiences torque.
Common Student Mistake: Do not confuse current sensitivity with figure of merit, and do not use non-radial torque formula in radial field.
JEE Main MCQ 28In a radial magnetic field, torque on coil is Use a variation with N=80, B=0.3 T, A=4×10⁻⁴ m², k=4×10⁻⁶ N m rad⁻¹ or G=30 Ω.
  1. NBIA sinθ
  2. NBIA
  3. zero
  4. NBA/I
Correct Answer: B
Difficulty: Difficult
Concept Tested: Moving coil galvanometer principle, sensitivity, conversion and torque balance. Use a variation with N=80, B=0.3 T, A=4×10⁻⁴ m², k=4×10⁻⁶ N m rad⁻¹ or G=30 Ω.
Detailed Explanation: Area vector remains perpendicular to B, so sinα = 1.
Common Student Mistake: Do not confuse current sensitivity with figure of merit, and do not use non-radial torque formula in radial field.
JEE Main MCQ 29Current sensitivity of galvanometer is Use a variation with N=100, B=0.4 T, A=5×10⁻⁴ m², k=1×10⁻⁶ N m rad⁻¹ or G=40 Ω.
  1. θ/I
  2. I/θ
  3. V/θ
  4. G/I
Correct Answer: A
Difficulty: Difficult
Concept Tested: Moving coil galvanometer principle, sensitivity, conversion and torque balance. Use a variation with N=100, B=0.4 T, A=5×10⁻⁴ m², k=1×10⁻⁶ N m rad⁻¹ or G=40 Ω.
Detailed Explanation: Sᵢ = θ/I = NBA/k.
Common Student Mistake: Do not confuse current sensitivity with figure of merit, and do not use non-radial torque formula in radial field.
JEE Main MCQ 30Voltage sensitivity is Use a variation with N=120, B=0.5 T, A=6×10⁻⁴ m², k=2×10⁻⁶ N m rad⁻¹ or G=50 Ω.
  1. NBA/k
  2. NBA/kG
  3. k/NBA
  4. IgG
Correct Answer: B
Difficulty: Difficult
Concept Tested: Moving coil galvanometer principle, sensitivity, conversion and torque balance. Use a variation with N=120, B=0.5 T, A=6×10⁻⁴ m², k=2×10⁻⁶ N m rad⁻¹ or G=50 Ω.
Detailed Explanation: Sᵥ = θ/V = NBA/kG.
Common Student Mistake: Do not confuse current sensitivity with figure of merit, and do not use non-radial torque formula in radial field.
JEE Main MCQ 31Figure of merit is Use a variation with N=40, B=0.1 T, A=1×10⁻⁴ m², k=3×10⁻⁶ N m rad⁻¹ or G=10 Ω.
  1. θ/I
  2. I/θ
  3. V/I
  4. IG
Correct Answer: B
Difficulty: Difficult
Concept Tested: Moving coil galvanometer principle, sensitivity, conversion and torque balance. Use a variation with N=40, B=0.1 T, A=1×10⁻⁴ m², k=3×10⁻⁶ N m rad⁻¹ or G=10 Ω.
Detailed Explanation: It is current required for one division deflection.
Common Student Mistake: Do not confuse current sensitivity with figure of merit, and do not use non-radial torque formula in radial field.
JEE Main MCQ 32For ammeter conversion, shunt is connected Use a variation with N=60, B=0.2 T, A=2×10⁻⁴ m², k=4×10⁻⁶ N m rad⁻¹ or G=20 Ω.
  1. in series
  2. in parallel
  3. open circuit
  4. with scale only
Correct Answer: B
Difficulty: Difficult
Concept Tested: Moving coil galvanometer principle, sensitivity, conversion and torque balance. Use a variation with N=60, B=0.2 T, A=2×10⁻⁴ m², k=4×10⁻⁶ N m rad⁻¹ or G=20 Ω.
Detailed Explanation: Low resistance shunt bypasses most current.
Common Student Mistake: Do not confuse current sensitivity with figure of merit, and do not use non-radial torque formula in radial field.
JEE Main MCQ 33For voltmeter conversion, resistance is connected Use a variation with N=80, B=0.3 T, A=3×10⁻⁴ m², k=1×10⁻⁶ N m rad⁻¹ or G=30 Ω.
  1. in parallel
  2. in series
  3. in short
  4. not needed
Correct Answer: B
Difficulty: Difficult
Concept Tested: Moving coil galvanometer principle, sensitivity, conversion and torque balance. Use a variation with N=80, B=0.3 T, A=3×10⁻⁴ m², k=1×10⁻⁶ N m rad⁻¹ or G=30 Ω.
Detailed Explanation: High resistance in series limits current.
Common Student Mistake: Do not confuse current sensitivity with figure of merit, and do not use non-radial torque formula in radial field.
JEE Main MCQ 34Soft iron core is used to Use a variation with N=100, B=0.4 T, A=4×10⁻⁴ m², k=2×10⁻⁶ N m rad⁻¹ or G=40 Ω.
  1. decrease B
  2. increase and radialize B
  3. remove current
  4. increase friction
Correct Answer: B
Difficulty: Difficult
Concept Tested: Moving coil galvanometer principle, sensitivity, conversion and torque balance. Use a variation with N=100, B=0.4 T, A=4×10⁻⁴ m², k=2×10⁻⁶ N m rad⁻¹ or G=40 Ω.
Detailed Explanation: It strengthens field and helps make it radial.
Common Student Mistake: Do not confuse current sensitivity with figure of merit, and do not use non-radial torque formula in radial field.
JEE Main MCQ 35Phosphor bronze strip provides Use a variation with N=120, B=0.5 T, A=5×10⁻⁴ m², k=3×10⁻⁶ N m rad⁻¹ or G=50 Ω.
  1. only heat
  2. restoring torque and current path
  3. magnetic shielding
  4. AC rectification
Correct Answer: B
Difficulty: Difficult
Concept Tested: Moving coil galvanometer principle, sensitivity, conversion and torque balance. Use a variation with N=120, B=0.5 T, A=5×10⁻⁴ m², k=3×10⁻⁶ N m rad⁻¹ or G=50 Ω.
Detailed Explanation: It supports coil, conducts current and provides torsion.
Common Student Mistake: Do not confuse current sensitivity with figure of merit, and do not use non-radial torque formula in radial field.
JEE Main MCQ 36The scale is linear because Use a variation with N=40, B=0.1 T, A=6×10⁻⁴ m², k=4×10⁻⁶ N m rad⁻¹ or G=10 Ω.
  1. θ ∝ I
  2. θ ∝ I²
  3. θ independent of I
  4. B=0
Correct Answer: A
Difficulty: Difficult
Concept Tested: Moving coil galvanometer principle, sensitivity, conversion and torque balance. Use a variation with N=40, B=0.1 T, A=6×10⁻⁴ m², k=4×10⁻⁶ N m rad⁻¹ or G=10 Ω.
Detailed Explanation: From NBIA = kθ, θ = NBAI/k.
Common Student Mistake: Do not confuse current sensitivity with figure of merit, and do not use non-radial torque formula in radial field.
JEE Main MCQ 37A moving coil galvanometer works on Use a variation with N=60, B=0.2 T, A=1×10⁻⁴ m², k=1×10⁻⁶ N m rad⁻¹ or G=20 Ω.
  1. heating effect
  2. torque on current carrying coil
  3. photoelectric effect
  4. induction only
Correct Answer: B
Difficulty: Difficult
Concept Tested: Moving coil galvanometer principle, sensitivity, conversion and torque balance. Use a variation with N=60, B=0.2 T, A=1×10⁻⁴ m², k=1×10⁻⁶ N m rad⁻¹ or G=20 Ω.
Detailed Explanation: A current carrying coil in magnetic field experiences torque.
Common Student Mistake: Do not confuse current sensitivity with figure of merit, and do not use non-radial torque formula in radial field.
JEE Main MCQ 38In a radial magnetic field, torque on coil is Use a variation with N=80, B=0.3 T, A=2×10⁻⁴ m², k=2×10⁻⁶ N m rad⁻¹ or G=30 Ω.
  1. NBIA sinθ
  2. NBIA
  3. zero
  4. NBA/I
Correct Answer: B
Difficulty: Difficult
Concept Tested: Moving coil galvanometer principle, sensitivity, conversion and torque balance. Use a variation with N=80, B=0.3 T, A=2×10⁻⁴ m², k=2×10⁻⁶ N m rad⁻¹ or G=30 Ω.
Detailed Explanation: Area vector remains perpendicular to B, so sinα = 1.
Common Student Mistake: Do not confuse current sensitivity with figure of merit, and do not use non-radial torque formula in radial field.
JEE Main MCQ 39Current sensitivity of galvanometer is Use a variation with N=100, B=0.4 T, A=3×10⁻⁴ m², k=3×10⁻⁶ N m rad⁻¹ or G=40 Ω.
  1. θ/I
  2. I/θ
  3. V/θ
  4. G/I
Correct Answer: A
Difficulty: Difficult
Concept Tested: Moving coil galvanometer principle, sensitivity, conversion and torque balance. Use a variation with N=100, B=0.4 T, A=3×10⁻⁴ m², k=3×10⁻⁶ N m rad⁻¹ or G=40 Ω.
Detailed Explanation: Sᵢ = θ/I = NBA/k.
Common Student Mistake: Do not confuse current sensitivity with figure of merit, and do not use non-radial torque formula in radial field.
JEE Main MCQ 40Voltage sensitivity is Use a variation with N=120, B=0.5 T, A=4×10⁻⁴ m², k=4×10⁻⁶ N m rad⁻¹ or G=50 Ω.
  1. NBA/k
  2. NBA/kG
  3. k/NBA
  4. IgG
Correct Answer: B
Difficulty: Difficult
Concept Tested: Moving coil galvanometer principle, sensitivity, conversion and torque balance. Use a variation with N=120, B=0.5 T, A=4×10⁻⁴ m², k=4×10⁻⁶ N m rad⁻¹ or G=50 Ω.
Detailed Explanation: Sᵥ = θ/V = NBA/kG.
Common Student Mistake: Do not confuse current sensitivity with figure of merit, and do not use non-radial torque formula in radial field.
JEE Main MCQ 41Figure of merit is Use a variation with N=40, B=0.1 T, A=5×10⁻⁴ m², k=1×10⁻⁶ N m rad⁻¹ or G=10 Ω.
  1. θ/I
  2. I/θ
  3. V/I
  4. IG
Correct Answer: B
Difficulty: Difficult
Concept Tested: Moving coil galvanometer principle, sensitivity, conversion and torque balance. Use a variation with N=40, B=0.1 T, A=5×10⁻⁴ m², k=1×10⁻⁶ N m rad⁻¹ or G=10 Ω.
Detailed Explanation: It is current required for one division deflection.
Common Student Mistake: Do not confuse current sensitivity with figure of merit, and do not use non-radial torque formula in radial field.
JEE Main MCQ 42For ammeter conversion, shunt is connected Use a variation with N=60, B=0.2 T, A=6×10⁻⁴ m², k=2×10⁻⁶ N m rad⁻¹ or G=20 Ω.
  1. in series
  2. in parallel
  3. open circuit
  4. with scale only
Correct Answer: B
Difficulty: Difficult
Concept Tested: Moving coil galvanometer principle, sensitivity, conversion and torque balance. Use a variation with N=60, B=0.2 T, A=6×10⁻⁴ m², k=2×10⁻⁶ N m rad⁻¹ or G=20 Ω.
Detailed Explanation: Low resistance shunt bypasses most current.
Common Student Mistake: Do not confuse current sensitivity with figure of merit, and do not use non-radial torque formula in radial field.
JEE Main MCQ 43For voltmeter conversion, resistance is connected Use a variation with N=80, B=0.3 T, A=1×10⁻⁴ m², k=3×10⁻⁶ N m rad⁻¹ or G=30 Ω.
  1. in parallel
  2. in series
  3. in short
  4. not needed
Correct Answer: B
Difficulty: Difficult
Concept Tested: Moving coil galvanometer principle, sensitivity, conversion and torque balance. Use a variation with N=80, B=0.3 T, A=1×10⁻⁴ m², k=3×10⁻⁶ N m rad⁻¹ or G=30 Ω.
Detailed Explanation: High resistance in series limits current.
Common Student Mistake: Do not confuse current sensitivity with figure of merit, and do not use non-radial torque formula in radial field.
JEE Main MCQ 44Soft iron core is used to Use a variation with N=100, B=0.4 T, A=2×10⁻⁴ m², k=4×10⁻⁶ N m rad⁻¹ or G=40 Ω.
  1. decrease B
  2. increase and radialize B
  3. remove current
  4. increase friction
Correct Answer: B
Difficulty: Difficult
Concept Tested: Moving coil galvanometer principle, sensitivity, conversion and torque balance. Use a variation with N=100, B=0.4 T, A=2×10⁻⁴ m², k=4×10⁻⁶ N m rad⁻¹ or G=40 Ω.
Detailed Explanation: It strengthens field and helps make it radial.
Common Student Mistake: Do not confuse current sensitivity with figure of merit, and do not use non-radial torque formula in radial field.
JEE Main MCQ 45Phosphor bronze strip provides Use a variation with N=120, B=0.5 T, A=3×10⁻⁴ m², k=1×10⁻⁶ N m rad⁻¹ or G=50 Ω.
  1. only heat
  2. restoring torque and current path
  3. magnetic shielding
  4. AC rectification
Correct Answer: B
Difficulty: Difficult
Concept Tested: Moving coil galvanometer principle, sensitivity, conversion and torque balance. Use a variation with N=120, B=0.5 T, A=3×10⁻⁴ m², k=1×10⁻⁶ N m rad⁻¹ or G=50 Ω.
Detailed Explanation: It supports coil, conducts current and provides torsion.
Common Student Mistake: Do not confuse current sensitivity with figure of merit, and do not use non-radial torque formula in radial field.
JEE Main MCQ 46The scale is linear because Use a variation with N=40, B=0.1 T, A=4×10⁻⁴ m², k=2×10⁻⁶ N m rad⁻¹ or G=10 Ω.
  1. θ ∝ I
  2. θ ∝ I²
  3. θ independent of I
  4. B=0
Correct Answer: A
Difficulty: Difficult
Concept Tested: Moving coil galvanometer principle, sensitivity, conversion and torque balance. Use a variation with N=40, B=0.1 T, A=4×10⁻⁴ m², k=2×10⁻⁶ N m rad⁻¹ or G=10 Ω.
Detailed Explanation: From NBIA = kθ, θ = NBAI/k.
Common Student Mistake: Do not confuse current sensitivity with figure of merit, and do not use non-radial torque formula in radial field.
JEE Main MCQ 47A moving coil galvanometer works on Use a variation with N=60, B=0.2 T, A=5×10⁻⁴ m², k=3×10⁻⁶ N m rad⁻¹ or G=20 Ω.
  1. heating effect
  2. torque on current carrying coil
  3. photoelectric effect
  4. induction only
Correct Answer: B
Difficulty: Difficult
Concept Tested: Moving coil galvanometer principle, sensitivity, conversion and torque balance. Use a variation with N=60, B=0.2 T, A=5×10⁻⁴ m², k=3×10⁻⁶ N m rad⁻¹ or G=20 Ω.
Detailed Explanation: A current carrying coil in magnetic field experiences torque.
Common Student Mistake: Do not confuse current sensitivity with figure of merit, and do not use non-radial torque formula in radial field.
JEE Main MCQ 48In a radial magnetic field, torque on coil is Use a variation with N=80, B=0.3 T, A=6×10⁻⁴ m², k=4×10⁻⁶ N m rad⁻¹ or G=30 Ω.
  1. NBIA sinθ
  2. NBIA
  3. zero
  4. NBA/I
Correct Answer: B
Difficulty: Difficult
Concept Tested: Moving coil galvanometer principle, sensitivity, conversion and torque balance. Use a variation with N=80, B=0.3 T, A=6×10⁻⁴ m², k=4×10⁻⁶ N m rad⁻¹ or G=30 Ω.
Detailed Explanation: Area vector remains perpendicular to B, so sinα = 1.
Common Student Mistake: Do not confuse current sensitivity with figure of merit, and do not use non-radial torque formula in radial field.
JEE Main MCQ 49Current sensitivity of galvanometer is Use a variation with N=100, B=0.4 T, A=1×10⁻⁴ m², k=1×10⁻⁶ N m rad⁻¹ or G=40 Ω.
  1. θ/I
  2. I/θ
  3. V/θ
  4. G/I
Correct Answer: A
Difficulty: Difficult
Concept Tested: Moving coil galvanometer principle, sensitivity, conversion and torque balance. Use a variation with N=100, B=0.4 T, A=1×10⁻⁴ m², k=1×10⁻⁶ N m rad⁻¹ or G=40 Ω.
Detailed Explanation: Sᵢ = θ/I = NBA/k.
Common Student Mistake: Do not confuse current sensitivity with figure of merit, and do not use non-radial torque formula in radial field.
JEE Main MCQ 50Voltage sensitivity is Use a variation with N=120, B=0.5 T, A=2×10⁻⁴ m², k=2×10⁻⁶ N m rad⁻¹ or G=50 Ω.
  1. NBA/k
  2. NBA/kG
  3. k/NBA
  4. IgG
Correct Answer: B
Difficulty: Difficult
Concept Tested: Moving coil galvanometer principle, sensitivity, conversion and torque balance. Use a variation with N=120, B=0.5 T, A=2×10⁻⁴ m², k=2×10⁻⁶ N m rad⁻¹ or G=50 Ω.
Detailed Explanation: Sᵥ = θ/V = NBA/kG.
Common Student Mistake: Do not confuse current sensitivity with figure of merit, and do not use non-radial torque formula in radial field.
JEE Main MCQ 51Figure of merit is Use a variation with N=40, B=0.1 T, A=3×10⁻⁴ m², k=3×10⁻⁶ N m rad⁻¹ or G=10 Ω.
  1. θ/I
  2. I/θ
  3. V/I
  4. IG
Correct Answer: B
Difficulty: Difficult
Concept Tested: Moving coil galvanometer principle, sensitivity, conversion and torque balance. Use a variation with N=40, B=0.1 T, A=3×10⁻⁴ m², k=3×10⁻⁶ N m rad⁻¹ or G=10 Ω.
Detailed Explanation: It is current required for one division deflection.
Common Student Mistake: Do not confuse current sensitivity with figure of merit, and do not use non-radial torque formula in radial field.
JEE Main MCQ 52For ammeter conversion, shunt is connected Use a variation with N=60, B=0.2 T, A=4×10⁻⁴ m², k=4×10⁻⁶ N m rad⁻¹ or G=20 Ω.
  1. in series
  2. in parallel
  3. open circuit
  4. with scale only
Correct Answer: B
Difficulty: Difficult
Concept Tested: Moving coil galvanometer principle, sensitivity, conversion and torque balance. Use a variation with N=60, B=0.2 T, A=4×10⁻⁴ m², k=4×10⁻⁶ N m rad⁻¹ or G=20 Ω.
Detailed Explanation: Low resistance shunt bypasses most current.
Common Student Mistake: Do not confuse current sensitivity with figure of merit, and do not use non-radial torque formula in radial field.
JEE Main MCQ 53For voltmeter conversion, resistance is connected Use a variation with N=80, B=0.3 T, A=5×10⁻⁴ m², k=1×10⁻⁶ N m rad⁻¹ or G=30 Ω.
  1. in parallel
  2. in series
  3. in short
  4. not needed
Correct Answer: B
Difficulty: Difficult
Concept Tested: Moving coil galvanometer principle, sensitivity, conversion and torque balance. Use a variation with N=80, B=0.3 T, A=5×10⁻⁴ m², k=1×10⁻⁶ N m rad⁻¹ or G=30 Ω.
Detailed Explanation: High resistance in series limits current.
Common Student Mistake: Do not confuse current sensitivity with figure of merit, and do not use non-radial torque formula in radial field.
JEE Main MCQ 54Soft iron core is used to Use a variation with N=100, B=0.4 T, A=6×10⁻⁴ m², k=2×10⁻⁶ N m rad⁻¹ or G=40 Ω.
  1. decrease B
  2. increase and radialize B
  3. remove current
  4. increase friction
Correct Answer: B
Difficulty: Difficult
Concept Tested: Moving coil galvanometer principle, sensitivity, conversion and torque balance. Use a variation with N=100, B=0.4 T, A=6×10⁻⁴ m², k=2×10⁻⁶ N m rad⁻¹ or G=40 Ω.
Detailed Explanation: It strengthens field and helps make it radial.
Common Student Mistake: Do not confuse current sensitivity with figure of merit, and do not use non-radial torque formula in radial field.
JEE Main MCQ 55Phosphor bronze strip provides Use a variation with N=120, B=0.5 T, A=1×10⁻⁴ m², k=3×10⁻⁶ N m rad⁻¹ or G=50 Ω.
  1. only heat
  2. restoring torque and current path
  3. magnetic shielding
  4. AC rectification
Correct Answer: B
Difficulty: Difficult
Concept Tested: Moving coil galvanometer principle, sensitivity, conversion and torque balance. Use a variation with N=120, B=0.5 T, A=1×10⁻⁴ m², k=3×10⁻⁶ N m rad⁻¹ or G=50 Ω.
Detailed Explanation: It supports coil, conducts current and provides torsion.
Common Student Mistake: Do not confuse current sensitivity with figure of merit, and do not use non-radial torque formula in radial field.
JEE Main MCQ 56The scale is linear because Use a variation with N=40, B=0.1 T, A=2×10⁻⁴ m², k=4×10⁻⁶ N m rad⁻¹ or G=10 Ω.
  1. θ ∝ I
  2. θ ∝ I²
  3. θ independent of I
  4. B=0
Correct Answer: A
Difficulty: Difficult
Concept Tested: Moving coil galvanometer principle, sensitivity, conversion and torque balance. Use a variation with N=40, B=0.1 T, A=2×10⁻⁴ m², k=4×10⁻⁶ N m rad⁻¹ or G=10 Ω.
Detailed Explanation: From NBIA = kθ, θ = NBAI/k.
Common Student Mistake: Do not confuse current sensitivity with figure of merit, and do not use non-radial torque formula in radial field.
JEE Main MCQ 57A moving coil galvanometer works on Use a variation with N=60, B=0.2 T, A=3×10⁻⁴ m², k=1×10⁻⁶ N m rad⁻¹ or G=20 Ω.
  1. heating effect
  2. torque on current carrying coil
  3. photoelectric effect
  4. induction only
Correct Answer: B
Difficulty: Difficult
Concept Tested: Moving coil galvanometer principle, sensitivity, conversion and torque balance. Use a variation with N=60, B=0.2 T, A=3×10⁻⁴ m², k=1×10⁻⁶ N m rad⁻¹ or G=20 Ω.
Detailed Explanation: A current carrying coil in magnetic field experiences torque.
Common Student Mistake: Do not confuse current sensitivity with figure of merit, and do not use non-radial torque formula in radial field.
JEE Main MCQ 58In a radial magnetic field, torque on coil is Use a variation with N=80, B=0.3 T, A=4×10⁻⁴ m², k=2×10⁻⁶ N m rad⁻¹ or G=30 Ω.
  1. NBIA sinθ
  2. NBIA
  3. zero
  4. NBA/I
Correct Answer: B
Difficulty: Difficult
Concept Tested: Moving coil galvanometer principle, sensitivity, conversion and torque balance. Use a variation with N=80, B=0.3 T, A=4×10⁻⁴ m², k=2×10⁻⁶ N m rad⁻¹ or G=30 Ω.
Detailed Explanation: Area vector remains perpendicular to B, so sinα = 1.
Common Student Mistake: Do not confuse current sensitivity with figure of merit, and do not use non-radial torque formula in radial field.
JEE Main MCQ 59Current sensitivity of galvanometer is Use a variation with N=100, B=0.4 T, A=5×10⁻⁴ m², k=3×10⁻⁶ N m rad⁻¹ or G=40 Ω.
  1. θ/I
  2. I/θ
  3. V/θ
  4. G/I
Correct Answer: A
Difficulty: Difficult
Concept Tested: Moving coil galvanometer principle, sensitivity, conversion and torque balance. Use a variation with N=100, B=0.4 T, A=5×10⁻⁴ m², k=3×10⁻⁶ N m rad⁻¹ or G=40 Ω.
Detailed Explanation: Sᵢ = θ/I = NBA/k.
Common Student Mistake: Do not confuse current sensitivity with figure of merit, and do not use non-radial torque formula in radial field.
JEE Main MCQ 60Voltage sensitivity is Use a variation with N=120, B=0.5 T, A=6×10⁻⁴ m², k=4×10⁻⁶ N m rad⁻¹ or G=50 Ω.
  1. NBA/k
  2. NBA/kG
  3. k/NBA
  4. IgG
Correct Answer: B
Difficulty: Difficult
Concept Tested: Moving coil galvanometer principle, sensitivity, conversion and torque balance. Use a variation with N=120, B=0.5 T, A=6×10⁻⁴ m², k=4×10⁻⁶ N m rad⁻¹ or G=50 Ω.
Detailed Explanation: Sᵥ = θ/V = NBA/kG.
Common Student Mistake: Do not confuse current sensitivity with figure of merit, and do not use non-radial torque formula in radial field.
JEE Main MCQ 61Figure of merit is Use a variation with N=40, B=0.1 T, A=1×10⁻⁴ m², k=1×10⁻⁶ N m rad⁻¹ or G=10 Ω.
  1. θ/I
  2. I/θ
  3. V/I
  4. IG
Correct Answer: B
Difficulty: Difficult
Concept Tested: Moving coil galvanometer principle, sensitivity, conversion and torque balance. Use a variation with N=40, B=0.1 T, A=1×10⁻⁴ m², k=1×10⁻⁶ N m rad⁻¹ or G=10 Ω.
Detailed Explanation: It is current required for one division deflection.
Common Student Mistake: Do not confuse current sensitivity with figure of merit, and do not use non-radial torque formula in radial field.
JEE Main MCQ 62For ammeter conversion, shunt is connected Use a variation with N=60, B=0.2 T, A=2×10⁻⁴ m², k=2×10⁻⁶ N m rad⁻¹ or G=20 Ω.
  1. in series
  2. in parallel
  3. open circuit
  4. with scale only
Correct Answer: B
Difficulty: Difficult
Concept Tested: Moving coil galvanometer principle, sensitivity, conversion and torque balance. Use a variation with N=60, B=0.2 T, A=2×10⁻⁴ m², k=2×10⁻⁶ N m rad⁻¹ or G=20 Ω.
Detailed Explanation: Low resistance shunt bypasses most current.
Common Student Mistake: Do not confuse current sensitivity with figure of merit, and do not use non-radial torque formula in radial field.
JEE Main MCQ 63For voltmeter conversion, resistance is connected Use a variation with N=80, B=0.3 T, A=3×10⁻⁴ m², k=3×10⁻⁶ N m rad⁻¹ or G=30 Ω.
  1. in parallel
  2. in series
  3. in short
  4. not needed
Correct Answer: B
Difficulty: Difficult
Concept Tested: Moving coil galvanometer principle, sensitivity, conversion and torque balance. Use a variation with N=80, B=0.3 T, A=3×10⁻⁴ m², k=3×10⁻⁶ N m rad⁻¹ or G=30 Ω.
Detailed Explanation: High resistance in series limits current.
Common Student Mistake: Do not confuse current sensitivity with figure of merit, and do not use non-radial torque formula in radial field.
JEE Main MCQ 64Soft iron core is used to Use a variation with N=100, B=0.4 T, A=4×10⁻⁴ m², k=4×10⁻⁶ N m rad⁻¹ or G=40 Ω.
  1. decrease B
  2. increase and radialize B
  3. remove current
  4. increase friction
Correct Answer: B
Difficulty: Difficult
Concept Tested: Moving coil galvanometer principle, sensitivity, conversion and torque balance. Use a variation with N=100, B=0.4 T, A=4×10⁻⁴ m², k=4×10⁻⁶ N m rad⁻¹ or G=40 Ω.
Detailed Explanation: It strengthens field and helps make it radial.
Common Student Mistake: Do not confuse current sensitivity with figure of merit, and do not use non-radial torque formula in radial field.
JEE Main MCQ 65Phosphor bronze strip provides Use a variation with N=120, B=0.5 T, A=5×10⁻⁴ m², k=1×10⁻⁶ N m rad⁻¹ or G=50 Ω.
  1. only heat
  2. restoring torque and current path
  3. magnetic shielding
  4. AC rectification
Correct Answer: B
Difficulty: Difficult
Concept Tested: Moving coil galvanometer principle, sensitivity, conversion and torque balance. Use a variation with N=120, B=0.5 T, A=5×10⁻⁴ m², k=1×10⁻⁶ N m rad⁻¹ or G=50 Ω.
Detailed Explanation: It supports coil, conducts current and provides torsion.
Common Student Mistake: Do not confuse current sensitivity with figure of merit, and do not use non-radial torque formula in radial field.
JEE Main MCQ 66The scale is linear because Use a variation with N=40, B=0.1 T, A=6×10⁻⁴ m², k=2×10⁻⁶ N m rad⁻¹ or G=10 Ω.
  1. θ ∝ I
  2. θ ∝ I²
  3. θ independent of I
  4. B=0
Correct Answer: A
Difficulty: Difficult
Concept Tested: Moving coil galvanometer principle, sensitivity, conversion and torque balance. Use a variation with N=40, B=0.1 T, A=6×10⁻⁴ m², k=2×10⁻⁶ N m rad⁻¹ or G=10 Ω.
Detailed Explanation: From NBIA = kθ, θ = NBAI/k.
Common Student Mistake: Do not confuse current sensitivity with figure of merit, and do not use non-radial torque formula in radial field.
JEE Main MCQ 67A moving coil galvanometer works on Use a variation with N=60, B=0.2 T, A=1×10⁻⁴ m², k=3×10⁻⁶ N m rad⁻¹ or G=20 Ω.
  1. heating effect
  2. torque on current carrying coil
  3. photoelectric effect
  4. induction only
Correct Answer: B
Difficulty: Difficult
Concept Tested: Moving coil galvanometer principle, sensitivity, conversion and torque balance. Use a variation with N=60, B=0.2 T, A=1×10⁻⁴ m², k=3×10⁻⁶ N m rad⁻¹ or G=20 Ω.
Detailed Explanation: A current carrying coil in magnetic field experiences torque.
Common Student Mistake: Do not confuse current sensitivity with figure of merit, and do not use non-radial torque formula in radial field.
JEE Main MCQ 68In a radial magnetic field, torque on coil is Use a variation with N=80, B=0.3 T, A=2×10⁻⁴ m², k=4×10⁻⁶ N m rad⁻¹ or G=30 Ω.
  1. NBIA sinθ
  2. NBIA
  3. zero
  4. NBA/I
Correct Answer: B
Difficulty: Difficult
Concept Tested: Moving coil galvanometer principle, sensitivity, conversion and torque balance. Use a variation with N=80, B=0.3 T, A=2×10⁻⁴ m², k=4×10⁻⁶ N m rad⁻¹ or G=30 Ω.
Detailed Explanation: Area vector remains perpendicular to B, so sinα = 1.
Common Student Mistake: Do not confuse current sensitivity with figure of merit, and do not use non-radial torque formula in radial field.
JEE Main MCQ 69Current sensitivity of galvanometer is Use a variation with N=100, B=0.4 T, A=3×10⁻⁴ m², k=1×10⁻⁶ N m rad⁻¹ or G=40 Ω.
  1. θ/I
  2. I/θ
  3. V/θ
  4. G/I
Correct Answer: A
Difficulty: Difficult
Concept Tested: Moving coil galvanometer principle, sensitivity, conversion and torque balance. Use a variation with N=100, B=0.4 T, A=3×10⁻⁴ m², k=1×10⁻⁶ N m rad⁻¹ or G=40 Ω.
Detailed Explanation: Sᵢ = θ/I = NBA/k.
Common Student Mistake: Do not confuse current sensitivity with figure of merit, and do not use non-radial torque formula in radial field.
JEE Main MCQ 70Voltage sensitivity is Use a variation with N=120, B=0.5 T, A=4×10⁻⁴ m², k=2×10⁻⁶ N m rad⁻¹ or G=50 Ω.
  1. NBA/k
  2. NBA/kG
  3. k/NBA
  4. IgG
Correct Answer: B
Difficulty: Difficult
Concept Tested: Moving coil galvanometer principle, sensitivity, conversion and torque balance. Use a variation with N=120, B=0.5 T, A=4×10⁻⁴ m², k=2×10⁻⁶ N m rad⁻¹ or G=50 Ω.
Detailed Explanation: Sᵥ = θ/V = NBA/kG.
Common Student Mistake: Do not confuse current sensitivity with figure of merit, and do not use non-radial torque formula in radial field.
JEE Main MCQ 71Figure of merit is Use a variation with N=40, B=0.1 T, A=5×10⁻⁴ m², k=3×10⁻⁶ N m rad⁻¹ or G=10 Ω.
  1. θ/I
  2. I/θ
  3. V/I
  4. IG
Correct Answer: B
Difficulty: Difficult
Concept Tested: Moving coil galvanometer principle, sensitivity, conversion and torque balance. Use a variation with N=40, B=0.1 T, A=5×10⁻⁴ m², k=3×10⁻⁶ N m rad⁻¹ or G=10 Ω.
Detailed Explanation: It is current required for one division deflection.
Common Student Mistake: Do not confuse current sensitivity with figure of merit, and do not use non-radial torque formula in radial field.
JEE Main MCQ 72For ammeter conversion, shunt is connected Use a variation with N=60, B=0.2 T, A=6×10⁻⁴ m², k=4×10⁻⁶ N m rad⁻¹ or G=20 Ω.
  1. in series
  2. in parallel
  3. open circuit
  4. with scale only
Correct Answer: B
Difficulty: Difficult
Concept Tested: Moving coil galvanometer principle, sensitivity, conversion and torque balance. Use a variation with N=60, B=0.2 T, A=6×10⁻⁴ m², k=4×10⁻⁶ N m rad⁻¹ or G=20 Ω.
Detailed Explanation: Low resistance shunt bypasses most current.
Common Student Mistake: Do not confuse current sensitivity with figure of merit, and do not use non-radial torque formula in radial field.
JEE Main MCQ 73For voltmeter conversion, resistance is connected Use a variation with N=80, B=0.3 T, A=1×10⁻⁴ m², k=1×10⁻⁶ N m rad⁻¹ or G=30 Ω.
  1. in parallel
  2. in series
  3. in short
  4. not needed
Correct Answer: B
Difficulty: Difficult
Concept Tested: Moving coil galvanometer principle, sensitivity, conversion and torque balance. Use a variation with N=80, B=0.3 T, A=1×10⁻⁴ m², k=1×10⁻⁶ N m rad⁻¹ or G=30 Ω.
Detailed Explanation: High resistance in series limits current.
Common Student Mistake: Do not confuse current sensitivity with figure of merit, and do not use non-radial torque formula in radial field.
JEE Main MCQ 74Soft iron core is used to Use a variation with N=100, B=0.4 T, A=2×10⁻⁴ m², k=2×10⁻⁶ N m rad⁻¹ or G=40 Ω.
  1. decrease B
  2. increase and radialize B
  3. remove current
  4. increase friction
Correct Answer: B
Difficulty: Difficult
Concept Tested: Moving coil galvanometer principle, sensitivity, conversion and torque balance. Use a variation with N=100, B=0.4 T, A=2×10⁻⁴ m², k=2×10⁻⁶ N m rad⁻¹ or G=40 Ω.
Detailed Explanation: It strengthens field and helps make it radial.
Common Student Mistake: Do not confuse current sensitivity with figure of merit, and do not use non-radial torque formula in radial field.
JEE Main MCQ 75Phosphor bronze strip provides Use a variation with N=120, B=0.5 T, A=3×10⁻⁴ m², k=3×10⁻⁶ N m rad⁻¹ or G=50 Ω.
  1. only heat
  2. restoring torque and current path
  3. magnetic shielding
  4. AC rectification
Correct Answer: B
Difficulty: Difficult
Concept Tested: Moving coil galvanometer principle, sensitivity, conversion and torque balance. Use a variation with N=120, B=0.5 T, A=3×10⁻⁴ m², k=3×10⁻⁶ N m rad⁻¹ or G=50 Ω.
Detailed Explanation: It supports coil, conducts current and provides torsion.
Common Student Mistake: Do not confuse current sensitivity with figure of merit, and do not use non-radial torque formula in radial field.

D. JEE Advanced Questions

JEE Advanced Single Correct MCQ 1Figure of merit is Use a variation with N=40, B=0.1 T, A=1×10⁻⁴ m², k=1×10⁻⁶ N m rad⁻¹ or G=10 Ω.
  1. θ/I
  2. I/θ
  3. V/I
  4. IG
Correct Answer: B
Difficulty: Difficult
Concept Tested: Moving coil galvanometer principle, sensitivity, conversion and torque balance. Use a variation with N=40, B=0.1 T, A=1×10⁻⁴ m², k=1×10⁻⁶ N m rad⁻¹ or G=10 Ω.
Detailed Explanation: It is current required for one division deflection.
Common Student Mistake: Do not confuse current sensitivity with figure of merit, and do not use non-radial torque formula in radial field.
JEE Advanced Single Correct MCQ 2For ammeter conversion, shunt is connected Use a variation with N=60, B=0.2 T, A=2×10⁻⁴ m², k=2×10⁻⁶ N m rad⁻¹ or G=20 Ω.
  1. in series
  2. in parallel
  3. open circuit
  4. with scale only
Correct Answer: B
Difficulty: Difficult
Concept Tested: Moving coil galvanometer principle, sensitivity, conversion and torque balance. Use a variation with N=60, B=0.2 T, A=2×10⁻⁴ m², k=2×10⁻⁶ N m rad⁻¹ or G=20 Ω.
Detailed Explanation: Low resistance shunt bypasses most current.
Common Student Mistake: Do not confuse current sensitivity with figure of merit, and do not use non-radial torque formula in radial field.
JEE Advanced Single Correct MCQ 3For voltmeter conversion, resistance is connected Use a variation with N=80, B=0.3 T, A=3×10⁻⁴ m², k=3×10⁻⁶ N m rad⁻¹ or G=30 Ω.
  1. in parallel
  2. in series
  3. in short
  4. not needed
Correct Answer: B
Difficulty: Difficult
Concept Tested: Moving coil galvanometer principle, sensitivity, conversion and torque balance. Use a variation with N=80, B=0.3 T, A=3×10⁻⁴ m², k=3×10⁻⁶ N m rad⁻¹ or G=30 Ω.
Detailed Explanation: High resistance in series limits current.
Common Student Mistake: Do not confuse current sensitivity with figure of merit, and do not use non-radial torque formula in radial field.
JEE Advanced Single Correct MCQ 4Soft iron core is used to Use a variation with N=100, B=0.4 T, A=4×10⁻⁴ m², k=4×10⁻⁶ N m rad⁻¹ or G=40 Ω.
  1. decrease B
  2. increase and radialize B
  3. remove current
  4. increase friction
Correct Answer: B
Difficulty: Difficult
Concept Tested: Moving coil galvanometer principle, sensitivity, conversion and torque balance. Use a variation with N=100, B=0.4 T, A=4×10⁻⁴ m², k=4×10⁻⁶ N m rad⁻¹ or G=40 Ω.
Detailed Explanation: It strengthens field and helps make it radial.
Common Student Mistake: Do not confuse current sensitivity with figure of merit, and do not use non-radial torque formula in radial field.
JEE Advanced Single Correct MCQ 5Phosphor bronze strip provides Use a variation with N=120, B=0.5 T, A=5×10⁻⁴ m², k=1×10⁻⁶ N m rad⁻¹ or G=50 Ω.
  1. only heat
  2. restoring torque and current path
  3. magnetic shielding
  4. AC rectification
Correct Answer: B
Difficulty: Difficult
Concept Tested: Moving coil galvanometer principle, sensitivity, conversion and torque balance. Use a variation with N=120, B=0.5 T, A=5×10⁻⁴ m², k=1×10⁻⁶ N m rad⁻¹ or G=50 Ω.
Detailed Explanation: It supports coil, conducts current and provides torsion.
Common Student Mistake: Do not confuse current sensitivity with figure of merit, and do not use non-radial torque formula in radial field.
JEE Advanced Single Correct MCQ 6The scale is linear because Use a variation with N=40, B=0.1 T, A=6×10⁻⁴ m², k=2×10⁻⁶ N m rad⁻¹ or G=10 Ω.
  1. θ ∝ I
  2. θ ∝ I²
  3. θ independent of I
  4. B=0
Correct Answer: A
Difficulty: Difficult
Concept Tested: Moving coil galvanometer principle, sensitivity, conversion and torque balance. Use a variation with N=40, B=0.1 T, A=6×10⁻⁴ m², k=2×10⁻⁶ N m rad⁻¹ or G=10 Ω.
Detailed Explanation: From NBIA = kθ, θ = NBAI/k.
Common Student Mistake: Do not confuse current sensitivity with figure of merit, and do not use non-radial torque formula in radial field.
JEE Advanced Single Correct MCQ 7A moving coil galvanometer works on Use a variation with N=60, B=0.2 T, A=1×10⁻⁴ m², k=3×10⁻⁶ N m rad⁻¹ or G=20 Ω.
  1. heating effect
  2. torque on current carrying coil
  3. photoelectric effect
  4. induction only
Correct Answer: B
Difficulty: Difficult
Concept Tested: Moving coil galvanometer principle, sensitivity, conversion and torque balance. Use a variation with N=60, B=0.2 T, A=1×10⁻⁴ m², k=3×10⁻⁶ N m rad⁻¹ or G=20 Ω.
Detailed Explanation: A current carrying coil in magnetic field experiences torque.
Common Student Mistake: Do not confuse current sensitivity with figure of merit, and do not use non-radial torque formula in radial field.
JEE Advanced Single Correct MCQ 8In a radial magnetic field, torque on coil is Use a variation with N=80, B=0.3 T, A=2×10⁻⁴ m², k=4×10⁻⁶ N m rad⁻¹ or G=30 Ω.
  1. NBIA sinθ
  2. NBIA
  3. zero
  4. NBA/I
Correct Answer: B
Difficulty: Difficult
Concept Tested: Moving coil galvanometer principle, sensitivity, conversion and torque balance. Use a variation with N=80, B=0.3 T, A=2×10⁻⁴ m², k=4×10⁻⁶ N m rad⁻¹ or G=30 Ω.
Detailed Explanation: Area vector remains perpendicular to B, so sinα = 1.
Common Student Mistake: Do not confuse current sensitivity with figure of merit, and do not use non-radial torque formula in radial field.
JEE Advanced Single Correct MCQ 9Current sensitivity of galvanometer is Use a variation with N=100, B=0.4 T, A=3×10⁻⁴ m², k=1×10⁻⁶ N m rad⁻¹ or G=40 Ω.
  1. θ/I
  2. I/θ
  3. V/θ
  4. G/I
Correct Answer: A
Difficulty: Difficult
Concept Tested: Moving coil galvanometer principle, sensitivity, conversion and torque balance. Use a variation with N=100, B=0.4 T, A=3×10⁻⁴ m², k=1×10⁻⁶ N m rad⁻¹ or G=40 Ω.
Detailed Explanation: Sᵢ = θ/I = NBA/k.
Common Student Mistake: Do not confuse current sensitivity with figure of merit, and do not use non-radial torque formula in radial field.
JEE Advanced Single Correct MCQ 10Voltage sensitivity is Use a variation with N=120, B=0.5 T, A=4×10⁻⁴ m², k=2×10⁻⁶ N m rad⁻¹ or G=50 Ω.
  1. NBA/k
  2. NBA/kG
  3. k/NBA
  4. IgG
Correct Answer: B
Difficulty: Difficult
Concept Tested: Moving coil galvanometer principle, sensitivity, conversion and torque balance. Use a variation with N=120, B=0.5 T, A=4×10⁻⁴ m², k=2×10⁻⁶ N m rad⁻¹ or G=50 Ω.
Detailed Explanation: Sᵥ = θ/V = NBA/kG.
Common Student Mistake: Do not confuse current sensitivity with figure of merit, and do not use non-radial torque formula in radial field.
JEE Advanced Single Correct MCQ 11Figure of merit is Use a variation with N=40, B=0.1 T, A=5×10⁻⁴ m², k=3×10⁻⁶ N m rad⁻¹ or G=10 Ω.
  1. θ/I
  2. I/θ
  3. V/I
  4. IG
Correct Answer: B
Difficulty: Difficult
Concept Tested: Moving coil galvanometer principle, sensitivity, conversion and torque balance. Use a variation with N=40, B=0.1 T, A=5×10⁻⁴ m², k=3×10⁻⁶ N m rad⁻¹ or G=10 Ω.
Detailed Explanation: It is current required for one division deflection.
Common Student Mistake: Do not confuse current sensitivity with figure of merit, and do not use non-radial torque formula in radial field.
JEE Advanced Single Correct MCQ 12For ammeter conversion, shunt is connected Use a variation with N=60, B=0.2 T, A=6×10⁻⁴ m², k=4×10⁻⁶ N m rad⁻¹ or G=20 Ω.
  1. in series
  2. in parallel
  3. open circuit
  4. with scale only
Correct Answer: B
Difficulty: Difficult
Concept Tested: Moving coil galvanometer principle, sensitivity, conversion and torque balance. Use a variation with N=60, B=0.2 T, A=6×10⁻⁴ m², k=4×10⁻⁶ N m rad⁻¹ or G=20 Ω.
Detailed Explanation: Low resistance shunt bypasses most current.
Common Student Mistake: Do not confuse current sensitivity with figure of merit, and do not use non-radial torque formula in radial field.
JEE Advanced Single Correct MCQ 13For voltmeter conversion, resistance is connected Use a variation with N=80, B=0.3 T, A=1×10⁻⁴ m², k=1×10⁻⁶ N m rad⁻¹ or G=30 Ω.
  1. in parallel
  2. in series
  3. in short
  4. not needed
Correct Answer: B
Difficulty: Difficult
Concept Tested: Moving coil galvanometer principle, sensitivity, conversion and torque balance. Use a variation with N=80, B=0.3 T, A=1×10⁻⁴ m², k=1×10⁻⁶ N m rad⁻¹ or G=30 Ω.
Detailed Explanation: High resistance in series limits current.
Common Student Mistake: Do not confuse current sensitivity with figure of merit, and do not use non-radial torque formula in radial field.
JEE Advanced Single Correct MCQ 14Soft iron core is used to Use a variation with N=100, B=0.4 T, A=2×10⁻⁴ m², k=2×10⁻⁶ N m rad⁻¹ or G=40 Ω.
  1. decrease B
  2. increase and radialize B
  3. remove current
  4. increase friction
Correct Answer: B
Difficulty: Difficult
Concept Tested: Moving coil galvanometer principle, sensitivity, conversion and torque balance. Use a variation with N=100, B=0.4 T, A=2×10⁻⁴ m², k=2×10⁻⁶ N m rad⁻¹ or G=40 Ω.
Detailed Explanation: It strengthens field and helps make it radial.
Common Student Mistake: Do not confuse current sensitivity with figure of merit, and do not use non-radial torque formula in radial field.
JEE Advanced Single Correct MCQ 15Phosphor bronze strip provides Use a variation with N=120, B=0.5 T, A=3×10⁻⁴ m², k=3×10⁻⁶ N m rad⁻¹ or G=50 Ω.
  1. only heat
  2. restoring torque and current path
  3. magnetic shielding
  4. AC rectification
Correct Answer: B
Difficulty: Difficult
Concept Tested: Moving coil galvanometer principle, sensitivity, conversion and torque balance. Use a variation with N=120, B=0.5 T, A=3×10⁻⁴ m², k=3×10⁻⁶ N m rad⁻¹ or G=50 Ω.
Detailed Explanation: It supports coil, conducts current and provides torsion.
Common Student Mistake: Do not confuse current sensitivity with figure of merit, and do not use non-radial torque formula in radial field.
JEE Advanced Single Correct MCQ 16The scale is linear because Use a variation with N=40, B=0.1 T, A=4×10⁻⁴ m², k=4×10⁻⁶ N m rad⁻¹ or G=10 Ω.
  1. θ ∝ I
  2. θ ∝ I²
  3. θ independent of I
  4. B=0
Correct Answer: A
Difficulty: Difficult
Concept Tested: Moving coil galvanometer principle, sensitivity, conversion and torque balance. Use a variation with N=40, B=0.1 T, A=4×10⁻⁴ m², k=4×10⁻⁶ N m rad⁻¹ or G=10 Ω.
Detailed Explanation: From NBIA = kθ, θ = NBAI/k.
Common Student Mistake: Do not confuse current sensitivity with figure of merit, and do not use non-radial torque formula in radial field.
JEE Advanced Single Correct MCQ 17A moving coil galvanometer works on Use a variation with N=60, B=0.2 T, A=5×10⁻⁴ m², k=1×10⁻⁶ N m rad⁻¹ or G=20 Ω.
  1. heating effect
  2. torque on current carrying coil
  3. photoelectric effect
  4. induction only
Correct Answer: B
Difficulty: Difficult
Concept Tested: Moving coil galvanometer principle, sensitivity, conversion and torque balance. Use a variation with N=60, B=0.2 T, A=5×10⁻⁴ m², k=1×10⁻⁶ N m rad⁻¹ or G=20 Ω.
Detailed Explanation: A current carrying coil in magnetic field experiences torque.
Common Student Mistake: Do not confuse current sensitivity with figure of merit, and do not use non-radial torque formula in radial field.
JEE Advanced Single Correct MCQ 18In a radial magnetic field, torque on coil is Use a variation with N=80, B=0.3 T, A=6×10⁻⁴ m², k=2×10⁻⁶ N m rad⁻¹ or G=30 Ω.
  1. NBIA sinθ
  2. NBIA
  3. zero
  4. NBA/I
Correct Answer: B
Difficulty: Difficult
Concept Tested: Moving coil galvanometer principle, sensitivity, conversion and torque balance. Use a variation with N=80, B=0.3 T, A=6×10⁻⁴ m², k=2×10⁻⁶ N m rad⁻¹ or G=30 Ω.
Detailed Explanation: Area vector remains perpendicular to B, so sinα = 1.
Common Student Mistake: Do not confuse current sensitivity with figure of merit, and do not use non-radial torque formula in radial field.
JEE Advanced Single Correct MCQ 19Current sensitivity of galvanometer is Use a variation with N=100, B=0.4 T, A=1×10⁻⁴ m², k=3×10⁻⁶ N m rad⁻¹ or G=40 Ω.
  1. θ/I
  2. I/θ
  3. V/θ
  4. G/I
Correct Answer: A
Difficulty: Difficult
Concept Tested: Moving coil galvanometer principle, sensitivity, conversion and torque balance. Use a variation with N=100, B=0.4 T, A=1×10⁻⁴ m², k=3×10⁻⁶ N m rad⁻¹ or G=40 Ω.
Detailed Explanation: Sᵢ = θ/I = NBA/k.
Common Student Mistake: Do not confuse current sensitivity with figure of merit, and do not use non-radial torque formula in radial field.
JEE Advanced Single Correct MCQ 20Voltage sensitivity is Use a variation with N=120, B=0.5 T, A=2×10⁻⁴ m², k=4×10⁻⁶ N m rad⁻¹ or G=50 Ω.
  1. NBA/k
  2. NBA/kG
  3. k/NBA
  4. IgG
Correct Answer: B
Difficulty: Difficult
Concept Tested: Moving coil galvanometer principle, sensitivity, conversion and torque balance. Use a variation with N=120, B=0.5 T, A=2×10⁻⁴ m², k=4×10⁻⁶ N m rad⁻¹ or G=50 Ω.
Detailed Explanation: Sᵥ = θ/V = NBA/kG.
Common Student Mistake: Do not confuse current sensitivity with figure of merit, and do not use non-radial torque formula in radial field.
JEE Advanced Single Correct MCQ 21Figure of merit is Use a variation with N=40, B=0.1 T, A=3×10⁻⁴ m², k=1×10⁻⁶ N m rad⁻¹ or G=10 Ω.
  1. θ/I
  2. I/θ
  3. V/I
  4. IG
Correct Answer: B
Difficulty: Difficult
Concept Tested: Moving coil galvanometer principle, sensitivity, conversion and torque balance. Use a variation with N=40, B=0.1 T, A=3×10⁻⁴ m², k=1×10⁻⁶ N m rad⁻¹ or G=10 Ω.
Detailed Explanation: It is current required for one division deflection.
Common Student Mistake: Do not confuse current sensitivity with figure of merit, and do not use non-radial torque formula in radial field.
JEE Advanced Single Correct MCQ 22For ammeter conversion, shunt is connected Use a variation with N=60, B=0.2 T, A=4×10⁻⁴ m², k=2×10⁻⁶ N m rad⁻¹ or G=20 Ω.
  1. in series
  2. in parallel
  3. open circuit
  4. with scale only
Correct Answer: B
Difficulty: Difficult
Concept Tested: Moving coil galvanometer principle, sensitivity, conversion and torque balance. Use a variation with N=60, B=0.2 T, A=4×10⁻⁴ m², k=2×10⁻⁶ N m rad⁻¹ or G=20 Ω.
Detailed Explanation: Low resistance shunt bypasses most current.
Common Student Mistake: Do not confuse current sensitivity with figure of merit, and do not use non-radial torque formula in radial field.
JEE Advanced Single Correct MCQ 23For voltmeter conversion, resistance is connected Use a variation with N=80, B=0.3 T, A=5×10⁻⁴ m², k=3×10⁻⁶ N m rad⁻¹ or G=30 Ω.
  1. in parallel
  2. in series
  3. in short
  4. not needed
Correct Answer: B
Difficulty: Difficult
Concept Tested: Moving coil galvanometer principle, sensitivity, conversion and torque balance. Use a variation with N=80, B=0.3 T, A=5×10⁻⁴ m², k=3×10⁻⁶ N m rad⁻¹ or G=30 Ω.
Detailed Explanation: High resistance in series limits current.
Common Student Mistake: Do not confuse current sensitivity with figure of merit, and do not use non-radial torque formula in radial field.
JEE Advanced Single Correct MCQ 24Soft iron core is used to Use a variation with N=100, B=0.4 T, A=6×10⁻⁴ m², k=4×10⁻⁶ N m rad⁻¹ or G=40 Ω.
  1. decrease B
  2. increase and radialize B
  3. remove current
  4. increase friction
Correct Answer: B
Difficulty: Difficult
Concept Tested: Moving coil galvanometer principle, sensitivity, conversion and torque balance. Use a variation with N=100, B=0.4 T, A=6×10⁻⁴ m², k=4×10⁻⁶ N m rad⁻¹ or G=40 Ω.
Detailed Explanation: It strengthens field and helps make it radial.
Common Student Mistake: Do not confuse current sensitivity with figure of merit, and do not use non-radial torque formula in radial field.
JEE Advanced Single Correct MCQ 25Phosphor bronze strip provides Use a variation with N=120, B=0.5 T, A=1×10⁻⁴ m², k=1×10⁻⁶ N m rad⁻¹ or G=50 Ω.
  1. only heat
  2. restoring torque and current path
  3. magnetic shielding
  4. AC rectification
Correct Answer: B
Difficulty: Difficult
Concept Tested: Moving coil galvanometer principle, sensitivity, conversion and torque balance. Use a variation with N=120, B=0.5 T, A=1×10⁻⁴ m², k=1×10⁻⁶ N m rad⁻¹ or G=50 Ω.
Detailed Explanation: It supports coil, conducts current and provides torsion.
Common Student Mistake: Do not confuse current sensitivity with figure of merit, and do not use non-radial torque formula in radial field.
JEE Advanced Single Correct MCQ 26The scale is linear because Use a variation with N=40, B=0.1 T, A=2×10⁻⁴ m², k=2×10⁻⁶ N m rad⁻¹ or G=10 Ω.
  1. θ ∝ I
  2. θ ∝ I²
  3. θ independent of I
  4. B=0
Correct Answer: A
Difficulty: Difficult
Concept Tested: Moving coil galvanometer principle, sensitivity, conversion and torque balance. Use a variation with N=40, B=0.1 T, A=2×10⁻⁴ m², k=2×10⁻⁶ N m rad⁻¹ or G=10 Ω.
Detailed Explanation: From NBIA = kθ, θ = NBAI/k.
Common Student Mistake: Do not confuse current sensitivity with figure of merit, and do not use non-radial torque formula in radial field.
JEE Advanced Single Correct MCQ 27A moving coil galvanometer works on Use a variation with N=60, B=0.2 T, A=3×10⁻⁴ m², k=3×10⁻⁶ N m rad⁻¹ or G=20 Ω.
  1. heating effect
  2. torque on current carrying coil
  3. photoelectric effect
  4. induction only
Correct Answer: B
Difficulty: Difficult
Concept Tested: Moving coil galvanometer principle, sensitivity, conversion and torque balance. Use a variation with N=60, B=0.2 T, A=3×10⁻⁴ m², k=3×10⁻⁶ N m rad⁻¹ or G=20 Ω.
Detailed Explanation: A current carrying coil in magnetic field experiences torque.
Common Student Mistake: Do not confuse current sensitivity with figure of merit, and do not use non-radial torque formula in radial field.
JEE Advanced Single Correct MCQ 28In a radial magnetic field, torque on coil is Use a variation with N=80, B=0.3 T, A=4×10⁻⁴ m², k=4×10⁻⁶ N m rad⁻¹ or G=30 Ω.
  1. NBIA sinθ
  2. NBIA
  3. zero
  4. NBA/I
Correct Answer: B
Difficulty: Difficult
Concept Tested: Moving coil galvanometer principle, sensitivity, conversion and torque balance. Use a variation with N=80, B=0.3 T, A=4×10⁻⁴ m², k=4×10⁻⁶ N m rad⁻¹ or G=30 Ω.
Detailed Explanation: Area vector remains perpendicular to B, so sinα = 1.
Common Student Mistake: Do not confuse current sensitivity with figure of merit, and do not use non-radial torque formula in radial field.
JEE Advanced Single Correct MCQ 29Current sensitivity of galvanometer is Use a variation with N=100, B=0.4 T, A=5×10⁻⁴ m², k=1×10⁻⁶ N m rad⁻¹ or G=40 Ω.
  1. θ/I
  2. I/θ
  3. V/θ
  4. G/I
Correct Answer: A
Difficulty: Difficult
Concept Tested: Moving coil galvanometer principle, sensitivity, conversion and torque balance. Use a variation with N=100, B=0.4 T, A=5×10⁻⁴ m², k=1×10⁻⁶ N m rad⁻¹ or G=40 Ω.
Detailed Explanation: Sᵢ = θ/I = NBA/k.
Common Student Mistake: Do not confuse current sensitivity with figure of merit, and do not use non-radial torque formula in radial field.
JEE Advanced Single Correct MCQ 30Voltage sensitivity is Use a variation with N=120, B=0.5 T, A=6×10⁻⁴ m², k=2×10⁻⁶ N m rad⁻¹ or G=50 Ω.
  1. NBA/k
  2. NBA/kG
  3. k/NBA
  4. IgG
Correct Answer: B
Difficulty: Difficult
Concept Tested: Moving coil galvanometer principle, sensitivity, conversion and torque balance. Use a variation with N=120, B=0.5 T, A=6×10⁻⁴ m², k=2×10⁻⁶ N m rad⁻¹ or G=50 Ω.
Detailed Explanation: Sᵥ = θ/V = NBA/kG.
Common Student Mistake: Do not confuse current sensitivity with figure of merit, and do not use non-radial torque formula in radial field.
JEE Advanced Multiple Correct MCQ 1Figure of merit is Use a variation with N=40, B=0.1 T, A=1×10⁻⁴ m², k=1×10⁻⁶ N m rad⁻¹ or G=10 Ω.
  1. θ/I
  2. I/θ
  3. V/I
  4. IG
Correct Answer: B
Difficulty: Difficult
Concept Tested: Moving coil galvanometer principle, sensitivity, conversion and torque balance. Use a variation with N=40, B=0.1 T, A=1×10⁻⁴ m², k=1×10⁻⁶ N m rad⁻¹ or G=10 Ω.
Detailed Explanation: It is current required for one division deflection.
Common Student Mistake: Do not confuse current sensitivity with figure of merit, and do not use non-radial torque formula in radial field.
JEE Advanced Multiple Correct MCQ 2For ammeter conversion, shunt is connected Use a variation with N=60, B=0.2 T, A=2×10⁻⁴ m², k=2×10⁻⁶ N m rad⁻¹ or G=20 Ω.
  1. in series
  2. in parallel
  3. open circuit
  4. with scale only
Correct Answer: B
Difficulty: Difficult
Concept Tested: Moving coil galvanometer principle, sensitivity, conversion and torque balance. Use a variation with N=60, B=0.2 T, A=2×10⁻⁴ m², k=2×10⁻⁶ N m rad⁻¹ or G=20 Ω.
Detailed Explanation: Low resistance shunt bypasses most current.
Common Student Mistake: Do not confuse current sensitivity with figure of merit, and do not use non-radial torque formula in radial field.
JEE Advanced Multiple Correct MCQ 3For voltmeter conversion, resistance is connected Use a variation with N=80, B=0.3 T, A=3×10⁻⁴ m², k=3×10⁻⁶ N m rad⁻¹ or G=30 Ω.
  1. in parallel
  2. in series
  3. in short
  4. not needed
Correct Answer: B
Difficulty: Difficult
Concept Tested: Moving coil galvanometer principle, sensitivity, conversion and torque balance. Use a variation with N=80, B=0.3 T, A=3×10⁻⁴ m², k=3×10⁻⁶ N m rad⁻¹ or G=30 Ω.
Detailed Explanation: High resistance in series limits current.
Common Student Mistake: Do not confuse current sensitivity with figure of merit, and do not use non-radial torque formula in radial field.
JEE Advanced Multiple Correct MCQ 4Soft iron core is used to Use a variation with N=100, B=0.4 T, A=4×10⁻⁴ m², k=4×10⁻⁶ N m rad⁻¹ or G=40 Ω.
  1. decrease B
  2. increase and radialize B
  3. remove current
  4. increase friction
Correct Answer: B
Difficulty: Difficult
Concept Tested: Moving coil galvanometer principle, sensitivity, conversion and torque balance. Use a variation with N=100, B=0.4 T, A=4×10⁻⁴ m², k=4×10⁻⁶ N m rad⁻¹ or G=40 Ω.
Detailed Explanation: It strengthens field and helps make it radial.
Common Student Mistake: Do not confuse current sensitivity with figure of merit, and do not use non-radial torque formula in radial field.
JEE Advanced Multiple Correct MCQ 5Phosphor bronze strip provides Use a variation with N=120, B=0.5 T, A=5×10⁻⁴ m², k=1×10⁻⁶ N m rad⁻¹ or G=50 Ω.
  1. only heat
  2. restoring torque and current path
  3. magnetic shielding
  4. AC rectification
Correct Answer: B
Difficulty: Difficult
Concept Tested: Moving coil galvanometer principle, sensitivity, conversion and torque balance. Use a variation with N=120, B=0.5 T, A=5×10⁻⁴ m², k=1×10⁻⁶ N m rad⁻¹ or G=50 Ω.
Detailed Explanation: It supports coil, conducts current and provides torsion.
Common Student Mistake: Do not confuse current sensitivity with figure of merit, and do not use non-radial torque formula in radial field.
JEE Advanced Multiple Correct MCQ 6The scale is linear because Use a variation with N=40, B=0.1 T, A=6×10⁻⁴ m², k=2×10⁻⁶ N m rad⁻¹ or G=10 Ω.
  1. θ ∝ I
  2. θ ∝ I²
  3. θ independent of I
  4. B=0
Correct Answer: A
Difficulty: Difficult
Concept Tested: Moving coil galvanometer principle, sensitivity, conversion and torque balance. Use a variation with N=40, B=0.1 T, A=6×10⁻⁴ m², k=2×10⁻⁶ N m rad⁻¹ or G=10 Ω.
Detailed Explanation: From NBIA = kθ, θ = NBAI/k.
Common Student Mistake: Do not confuse current sensitivity with figure of merit, and do not use non-radial torque formula in radial field.
JEE Advanced Multiple Correct MCQ 7A moving coil galvanometer works on Use a variation with N=60, B=0.2 T, A=1×10⁻⁴ m², k=3×10⁻⁶ N m rad⁻¹ or G=20 Ω.
  1. heating effect
  2. torque on current carrying coil
  3. photoelectric effect
  4. induction only
Correct Answer: B
Difficulty: Difficult
Concept Tested: Moving coil galvanometer principle, sensitivity, conversion and torque balance. Use a variation with N=60, B=0.2 T, A=1×10⁻⁴ m², k=3×10⁻⁶ N m rad⁻¹ or G=20 Ω.
Detailed Explanation: A current carrying coil in magnetic field experiences torque.
Common Student Mistake: Do not confuse current sensitivity with figure of merit, and do not use non-radial torque formula in radial field.
JEE Advanced Multiple Correct MCQ 8In a radial magnetic field, torque on coil is Use a variation with N=80, B=0.3 T, A=2×10⁻⁴ m², k=4×10⁻⁶ N m rad⁻¹ or G=30 Ω.
  1. NBIA sinθ
  2. NBIA
  3. zero
  4. NBA/I
Correct Answer: B
Difficulty: Difficult
Concept Tested: Moving coil galvanometer principle, sensitivity, conversion and torque balance. Use a variation with N=80, B=0.3 T, A=2×10⁻⁴ m², k=4×10⁻⁶ N m rad⁻¹ or G=30 Ω.
Detailed Explanation: Area vector remains perpendicular to B, so sinα = 1.
Common Student Mistake: Do not confuse current sensitivity with figure of merit, and do not use non-radial torque formula in radial field.
JEE Advanced Multiple Correct MCQ 9Current sensitivity of galvanometer is Use a variation with N=100, B=0.4 T, A=3×10⁻⁴ m², k=1×10⁻⁶ N m rad⁻¹ or G=40 Ω.
  1. θ/I
  2. I/θ
  3. V/θ
  4. G/I
Correct Answer: A
Difficulty: Difficult
Concept Tested: Moving coil galvanometer principle, sensitivity, conversion and torque balance. Use a variation with N=100, B=0.4 T, A=3×10⁻⁴ m², k=1×10⁻⁶ N m rad⁻¹ or G=40 Ω.
Detailed Explanation: Sᵢ = θ/I = NBA/k.
Common Student Mistake: Do not confuse current sensitivity with figure of merit, and do not use non-radial torque formula in radial field.
JEE Advanced Multiple Correct MCQ 10Voltage sensitivity is Use a variation with N=120, B=0.5 T, A=4×10⁻⁴ m², k=2×10⁻⁶ N m rad⁻¹ or G=50 Ω.
  1. NBA/k
  2. NBA/kG
  3. k/NBA
  4. IgG
Correct Answer: B
Difficulty: Difficult
Concept Tested: Moving coil galvanometer principle, sensitivity, conversion and torque balance. Use a variation with N=120, B=0.5 T, A=4×10⁻⁴ m², k=2×10⁻⁶ N m rad⁻¹ or G=50 Ω.
Detailed Explanation: Sᵥ = θ/V = NBA/kG.
Common Student Mistake: Do not confuse current sensitivity with figure of merit, and do not use non-radial torque formula in radial field.
JEE Advanced Multiple Correct MCQ 11Figure of merit is Use a variation with N=40, B=0.1 T, A=5×10⁻⁴ m², k=3×10⁻⁶ N m rad⁻¹ or G=10 Ω.
  1. θ/I
  2. I/θ
  3. V/I
  4. IG
Correct Answer: B
Difficulty: Difficult
Concept Tested: Moving coil galvanometer principle, sensitivity, conversion and torque balance. Use a variation with N=40, B=0.1 T, A=5×10⁻⁴ m², k=3×10⁻⁶ N m rad⁻¹ or G=10 Ω.
Detailed Explanation: It is current required for one division deflection.
Common Student Mistake: Do not confuse current sensitivity with figure of merit, and do not use non-radial torque formula in radial field.
JEE Advanced Multiple Correct MCQ 12For ammeter conversion, shunt is connected Use a variation with N=60, B=0.2 T, A=6×10⁻⁴ m², k=4×10⁻⁶ N m rad⁻¹ or G=20 Ω.
  1. in series
  2. in parallel
  3. open circuit
  4. with scale only
Correct Answer: B
Difficulty: Difficult
Concept Tested: Moving coil galvanometer principle, sensitivity, conversion and torque balance. Use a variation with N=60, B=0.2 T, A=6×10⁻⁴ m², k=4×10⁻⁶ N m rad⁻¹ or G=20 Ω.
Detailed Explanation: Low resistance shunt bypasses most current.
Common Student Mistake: Do not confuse current sensitivity with figure of merit, and do not use non-radial torque formula in radial field.
JEE Advanced Multiple Correct MCQ 13For voltmeter conversion, resistance is connected Use a variation with N=80, B=0.3 T, A=1×10⁻⁴ m², k=1×10⁻⁶ N m rad⁻¹ or G=30 Ω.
  1. in parallel
  2. in series
  3. in short
  4. not needed
Correct Answer: B
Difficulty: Difficult
Concept Tested: Moving coil galvanometer principle, sensitivity, conversion and torque balance. Use a variation with N=80, B=0.3 T, A=1×10⁻⁴ m², k=1×10⁻⁶ N m rad⁻¹ or G=30 Ω.
Detailed Explanation: High resistance in series limits current.
Common Student Mistake: Do not confuse current sensitivity with figure of merit, and do not use non-radial torque formula in radial field.
JEE Advanced Multiple Correct MCQ 14Soft iron core is used to Use a variation with N=100, B=0.4 T, A=2×10⁻⁴ m², k=2×10⁻⁶ N m rad⁻¹ or G=40 Ω.
  1. decrease B
  2. increase and radialize B
  3. remove current
  4. increase friction
Correct Answer: B
Difficulty: Difficult
Concept Tested: Moving coil galvanometer principle, sensitivity, conversion and torque balance. Use a variation with N=100, B=0.4 T, A=2×10⁻⁴ m², k=2×10⁻⁶ N m rad⁻¹ or G=40 Ω.
Detailed Explanation: It strengthens field and helps make it radial.
Common Student Mistake: Do not confuse current sensitivity with figure of merit, and do not use non-radial torque formula in radial field.
JEE Advanced Multiple Correct MCQ 15Phosphor bronze strip provides Use a variation with N=120, B=0.5 T, A=3×10⁻⁴ m², k=3×10⁻⁶ N m rad⁻¹ or G=50 Ω.
  1. only heat
  2. restoring torque and current path
  3. magnetic shielding
  4. AC rectification
Correct Answer: B
Difficulty: Difficult
Concept Tested: Moving coil galvanometer principle, sensitivity, conversion and torque balance. Use a variation with N=120, B=0.5 T, A=3×10⁻⁴ m², k=3×10⁻⁶ N m rad⁻¹ or G=50 Ω.
Detailed Explanation: It supports coil, conducts current and provides torsion.
Common Student Mistake: Do not confuse current sensitivity with figure of merit, and do not use non-radial torque formula in radial field.
JEE Advanced Multiple Correct MCQ 16The scale is linear because Use a variation with N=40, B=0.1 T, A=4×10⁻⁴ m², k=4×10⁻⁶ N m rad⁻¹ or G=10 Ω.
  1. θ ∝ I
  2. θ ∝ I²
  3. θ independent of I
  4. B=0
Correct Answer: A
Difficulty: Difficult
Concept Tested: Moving coil galvanometer principle, sensitivity, conversion and torque balance. Use a variation with N=40, B=0.1 T, A=4×10⁻⁴ m², k=4×10⁻⁶ N m rad⁻¹ or G=10 Ω.
Detailed Explanation: From NBIA = kθ, θ = NBAI/k.
Common Student Mistake: Do not confuse current sensitivity with figure of merit, and do not use non-radial torque formula in radial field.
JEE Advanced Multiple Correct MCQ 17A moving coil galvanometer works on Use a variation with N=60, B=0.2 T, A=5×10⁻⁴ m², k=1×10⁻⁶ N m rad⁻¹ or G=20 Ω.
  1. heating effect
  2. torque on current carrying coil
  3. photoelectric effect
  4. induction only
Correct Answer: B
Difficulty: Difficult
Concept Tested: Moving coil galvanometer principle, sensitivity, conversion and torque balance. Use a variation with N=60, B=0.2 T, A=5×10⁻⁴ m², k=1×10⁻⁶ N m rad⁻¹ or G=20 Ω.
Detailed Explanation: A current carrying coil in magnetic field experiences torque.
Common Student Mistake: Do not confuse current sensitivity with figure of merit, and do not use non-radial torque formula in radial field.
JEE Advanced Multiple Correct MCQ 18In a radial magnetic field, torque on coil is Use a variation with N=80, B=0.3 T, A=6×10⁻⁴ m², k=2×10⁻⁶ N m rad⁻¹ or G=30 Ω.
  1. NBIA sinθ
  2. NBIA
  3. zero
  4. NBA/I
Correct Answer: B
Difficulty: Difficult
Concept Tested: Moving coil galvanometer principle, sensitivity, conversion and torque balance. Use a variation with N=80, B=0.3 T, A=6×10⁻⁴ m², k=2×10⁻⁶ N m rad⁻¹ or G=30 Ω.
Detailed Explanation: Area vector remains perpendicular to B, so sinα = 1.
Common Student Mistake: Do not confuse current sensitivity with figure of merit, and do not use non-radial torque formula in radial field.
JEE Advanced Multiple Correct MCQ 19Current sensitivity of galvanometer is Use a variation with N=100, B=0.4 T, A=1×10⁻⁴ m², k=3×10⁻⁶ N m rad⁻¹ or G=40 Ω.
  1. θ/I
  2. I/θ
  3. V/θ
  4. G/I
Correct Answer: A
Difficulty: Difficult
Concept Tested: Moving coil galvanometer principle, sensitivity, conversion and torque balance. Use a variation with N=100, B=0.4 T, A=1×10⁻⁴ m², k=3×10⁻⁶ N m rad⁻¹ or G=40 Ω.
Detailed Explanation: Sᵢ = θ/I = NBA/k.
Common Student Mistake: Do not confuse current sensitivity with figure of merit, and do not use non-radial torque formula in radial field.
JEE Advanced Multiple Correct MCQ 20Voltage sensitivity is Use a variation with N=120, B=0.5 T, A=2×10⁻⁴ m², k=4×10⁻⁶ N m rad⁻¹ or G=50 Ω.
  1. NBA/k
  2. NBA/kG
  3. k/NBA
  4. IgG
Correct Answer: B
Difficulty: Difficult
Concept Tested: Moving coil galvanometer principle, sensitivity, conversion and torque balance. Use a variation with N=120, B=0.5 T, A=2×10⁻⁴ m², k=4×10⁻⁶ N m rad⁻¹ or G=50 Ω.
Detailed Explanation: Sᵥ = θ/V = NBA/kG.
Common Student Mistake: Do not confuse current sensitivity with figure of merit, and do not use non-radial torque formula in radial field.
JEE Advanced Integer Question 1Explain construction of moving coil galvanometer.
Answer: A moving coil galvanometer uses a light rectangular coil suspended in a strong radial magnetic field between concave pole pieces and a soft iron core. Magnetic torque is NBIA and restoring torque is kθ. At equilibrium, NBIA = kθ, so I = kθ/NBA. This proves deflection is proportional to current. For conversion, use shunt S = IgG/(I − Ig) for ammeter and series resistance R = V/Ig − G for voltmeter.
JEE Advanced Integer Question 2Why are concave pole pieces used in a moving coil galvanometer?
Answer: A moving coil galvanometer uses a light rectangular coil suspended in a strong radial magnetic field between concave pole pieces and a soft iron core. Magnetic torque is NBIA and restoring torque is kθ. At equilibrium, NBIA = kθ, so I = kθ/NBA. This proves deflection is proportional to current. For conversion, use shunt S = IgG/(I − Ig) for ammeter and series resistance R = V/Ig − G for voltmeter.
JEE Advanced Integer Question 3Why is soft iron core used?
Answer: A moving coil galvanometer uses a light rectangular coil suspended in a strong radial magnetic field between concave pole pieces and a soft iron core. Magnetic torque is NBIA and restoring torque is kθ. At equilibrium, NBIA = kθ, so I = kθ/NBA. This proves deflection is proportional to current. For conversion, use shunt S = IgG/(I − Ig) for ammeter and series resistance R = V/Ig − G for voltmeter.
JEE Advanced Integer Question 4Derive I = kθ/NBA for a moving coil galvanometer.
Answer: A moving coil galvanometer uses a light rectangular coil suspended in a strong radial magnetic field between concave pole pieces and a soft iron core. Magnetic torque is NBIA and restoring torque is kθ. At equilibrium, NBIA = kθ, so I = kθ/NBA. This proves deflection is proportional to current. For conversion, use shunt S = IgG/(I − Ig) for ammeter and series resistance R = V/Ig − G for voltmeter.
JEE Advanced Integer Question 5Define current sensitivity and derive its expression.
Answer: A moving coil galvanometer uses a light rectangular coil suspended in a strong radial magnetic field between concave pole pieces and a soft iron core. Magnetic torque is NBIA and restoring torque is kθ. At equilibrium, NBIA = kθ, so I = kθ/NBA. This proves deflection is proportional to current. For conversion, use shunt S = IgG/(I − Ig) for ammeter and series resistance R = V/Ig − G for voltmeter.
JEE Advanced Integer Question 6Define voltage sensitivity and derive its expression.
Answer: A moving coil galvanometer uses a light rectangular coil suspended in a strong radial magnetic field between concave pole pieces and a soft iron core. Magnetic torque is NBIA and restoring torque is kθ. At equilibrium, NBIA = kθ, so I = kθ/NBA. This proves deflection is proportional to current. For conversion, use shunt S = IgG/(I − Ig) for ammeter and series resistance R = V/Ig − G for voltmeter.
JEE Advanced Integer Question 7Define figure of merit and explain its significance.
Answer: A moving coil galvanometer uses a light rectangular coil suspended in a strong radial magnetic field between concave pole pieces and a soft iron core. Magnetic torque is NBIA and restoring torque is kθ. At equilibrium, NBIA = kθ, so I = kθ/NBA. This proves deflection is proportional to current. For conversion, use shunt S = IgG/(I − Ig) for ammeter and series resistance R = V/Ig − G for voltmeter.
JEE Advanced Integer Question 8How is a galvanometer converted into an ammeter?
Answer: A moving coil galvanometer uses a light rectangular coil suspended in a strong radial magnetic field between concave pole pieces and a soft iron core. Magnetic torque is NBIA and restoring torque is kθ. At equilibrium, NBIA = kθ, so I = kθ/NBA. This proves deflection is proportional to current. For conversion, use shunt S = IgG/(I − Ig) for ammeter and series resistance R = V/Ig − G for voltmeter.
JEE Advanced Integer Question 9How is a galvanometer converted into a voltmeter?
Answer: A moving coil galvanometer uses a light rectangular coil suspended in a strong radial magnetic field between concave pole pieces and a soft iron core. Magnetic torque is NBIA and restoring torque is kθ. At equilibrium, NBIA = kθ, so I = kθ/NBA. This proves deflection is proportional to current. For conversion, use shunt S = IgG/(I − Ig) for ammeter and series resistance R = V/Ig − G for voltmeter.
JEE Advanced Integer Question 10Why is moving coil galvanometer mainly suitable for DC?
Answer: A moving coil galvanometer uses a light rectangular coil suspended in a strong radial magnetic field between concave pole pieces and a soft iron core. Magnetic torque is NBIA and restoring torque is kθ. At equilibrium, NBIA = kθ, so I = kθ/NBA. This proves deflection is proportional to current. For conversion, use shunt S = IgG/(I − Ig) for ammeter and series resistance R = V/Ig − G for voltmeter.
JEE Advanced Integer Question 11Explain construction of moving coil galvanometer.
Answer: A moving coil galvanometer uses a light rectangular coil suspended in a strong radial magnetic field between concave pole pieces and a soft iron core. Magnetic torque is NBIA and restoring torque is kθ. At equilibrium, NBIA = kθ, so I = kθ/NBA. This proves deflection is proportional to current. For conversion, use shunt S = IgG/(I − Ig) for ammeter and series resistance R = V/Ig − G for voltmeter.
JEE Advanced Integer Question 12Why are concave pole pieces used in a moving coil galvanometer?
Answer: A moving coil galvanometer uses a light rectangular coil suspended in a strong radial magnetic field between concave pole pieces and a soft iron core. Magnetic torque is NBIA and restoring torque is kθ. At equilibrium, NBIA = kθ, so I = kθ/NBA. This proves deflection is proportional to current. For conversion, use shunt S = IgG/(I − Ig) for ammeter and series resistance R = V/Ig − G for voltmeter.
JEE Advanced Integer Question 13Why is soft iron core used?
Answer: A moving coil galvanometer uses a light rectangular coil suspended in a strong radial magnetic field between concave pole pieces and a soft iron core. Magnetic torque is NBIA and restoring torque is kθ. At equilibrium, NBIA = kθ, so I = kθ/NBA. This proves deflection is proportional to current. For conversion, use shunt S = IgG/(I − Ig) for ammeter and series resistance R = V/Ig − G for voltmeter.
JEE Advanced Integer Question 14Derive I = kθ/NBA for a moving coil galvanometer.
Answer: A moving coil galvanometer uses a light rectangular coil suspended in a strong radial magnetic field between concave pole pieces and a soft iron core. Magnetic torque is NBIA and restoring torque is kθ. At equilibrium, NBIA = kθ, so I = kθ/NBA. This proves deflection is proportional to current. For conversion, use shunt S = IgG/(I − Ig) for ammeter and series resistance R = V/Ig − G for voltmeter.
JEE Advanced Integer Question 15Define current sensitivity and derive its expression.
Answer: A moving coil galvanometer uses a light rectangular coil suspended in a strong radial magnetic field between concave pole pieces and a soft iron core. Magnetic torque is NBIA and restoring torque is kθ. At equilibrium, NBIA = kθ, so I = kθ/NBA. This proves deflection is proportional to current. For conversion, use shunt S = IgG/(I − Ig) for ammeter and series resistance R = V/Ig − G for voltmeter.
JEE Advanced Matrix Match Question 1Explain construction of moving coil galvanometer.
Answer: A moving coil galvanometer uses a light rectangular coil suspended in a strong radial magnetic field between concave pole pieces and a soft iron core. Magnetic torque is NBIA and restoring torque is kθ. At equilibrium, NBIA = kθ, so I = kθ/NBA. This proves deflection is proportional to current. For conversion, use shunt S = IgG/(I − Ig) for ammeter and series resistance R = V/Ig − G for voltmeter.
JEE Advanced Matrix Match Question 2Why are concave pole pieces used in a moving coil galvanometer?
Answer: A moving coil galvanometer uses a light rectangular coil suspended in a strong radial magnetic field between concave pole pieces and a soft iron core. Magnetic torque is NBIA and restoring torque is kθ. At equilibrium, NBIA = kθ, so I = kθ/NBA. This proves deflection is proportional to current. For conversion, use shunt S = IgG/(I − Ig) for ammeter and series resistance R = V/Ig − G for voltmeter.
JEE Advanced Matrix Match Question 3Why is soft iron core used?
Answer: A moving coil galvanometer uses a light rectangular coil suspended in a strong radial magnetic field between concave pole pieces and a soft iron core. Magnetic torque is NBIA and restoring torque is kθ. At equilibrium, NBIA = kθ, so I = kθ/NBA. This proves deflection is proportional to current. For conversion, use shunt S = IgG/(I − Ig) for ammeter and series resistance R = V/Ig − G for voltmeter.
JEE Advanced Matrix Match Question 4Derive I = kθ/NBA for a moving coil galvanometer.
Answer: A moving coil galvanometer uses a light rectangular coil suspended in a strong radial magnetic field between concave pole pieces and a soft iron core. Magnetic torque is NBIA and restoring torque is kθ. At equilibrium, NBIA = kθ, so I = kθ/NBA. This proves deflection is proportional to current. For conversion, use shunt S = IgG/(I − Ig) for ammeter and series resistance R = V/Ig − G for voltmeter.
JEE Advanced Matrix Match Question 5Define current sensitivity and derive its expression.
Answer: A moving coil galvanometer uses a light rectangular coil suspended in a strong radial magnetic field between concave pole pieces and a soft iron core. Magnetic torque is NBIA and restoring torque is kθ. At equilibrium, NBIA = kθ, so I = kθ/NBA. This proves deflection is proportional to current. For conversion, use shunt S = IgG/(I − Ig) for ammeter and series resistance R = V/Ig − G for voltmeter.
JEE Advanced Matrix Match Question 6Define voltage sensitivity and derive its expression.
Answer: A moving coil galvanometer uses a light rectangular coil suspended in a strong radial magnetic field between concave pole pieces and a soft iron core. Magnetic torque is NBIA and restoring torque is kθ. At equilibrium, NBIA = kθ, so I = kθ/NBA. This proves deflection is proportional to current. For conversion, use shunt S = IgG/(I − Ig) for ammeter and series resistance R = V/Ig − G for voltmeter.
JEE Advanced Matrix Match Question 7Define figure of merit and explain its significance.
Answer: A moving coil galvanometer uses a light rectangular coil suspended in a strong radial magnetic field between concave pole pieces and a soft iron core. Magnetic torque is NBIA and restoring torque is kθ. At equilibrium, NBIA = kθ, so I = kθ/NBA. This proves deflection is proportional to current. For conversion, use shunt S = IgG/(I − Ig) for ammeter and series resistance R = V/Ig − G for voltmeter.
JEE Advanced Matrix Match Question 8How is a galvanometer converted into an ammeter?
Answer: A moving coil galvanometer uses a light rectangular coil suspended in a strong radial magnetic field between concave pole pieces and a soft iron core. Magnetic torque is NBIA and restoring torque is kθ. At equilibrium, NBIA = kθ, so I = kθ/NBA. This proves deflection is proportional to current. For conversion, use shunt S = IgG/(I − Ig) for ammeter and series resistance R = V/Ig − G for voltmeter.
JEE Advanced Matrix Match Question 9How is a galvanometer converted into a voltmeter?
Answer: A moving coil galvanometer uses a light rectangular coil suspended in a strong radial magnetic field between concave pole pieces and a soft iron core. Magnetic torque is NBIA and restoring torque is kθ. At equilibrium, NBIA = kθ, so I = kθ/NBA. This proves deflection is proportional to current. For conversion, use shunt S = IgG/(I − Ig) for ammeter and series resistance R = V/Ig − G for voltmeter.
JEE Advanced Matrix Match Question 10Why is moving coil galvanometer mainly suitable for DC?
Answer: A moving coil galvanometer uses a light rectangular coil suspended in a strong radial magnetic field between concave pole pieces and a soft iron core. Magnetic torque is NBIA and restoring torque is kθ. At equilibrium, NBIA = kθ, so I = kθ/NBA. This proves deflection is proportional to current. For conversion, use shunt S = IgG/(I − Ig) for ammeter and series resistance R = V/Ig − G for voltmeter.
JEE Advanced Paragraph Question 1Explain construction of moving coil galvanometer.
Answer: A moving coil galvanometer uses a light rectangular coil suspended in a strong radial magnetic field between concave pole pieces and a soft iron core. Magnetic torque is NBIA and restoring torque is kθ. At equilibrium, NBIA = kθ, so I = kθ/NBA. This proves deflection is proportional to current. For conversion, use shunt S = IgG/(I − Ig) for ammeter and series resistance R = V/Ig − G for voltmeter.
JEE Advanced Paragraph Question 2Why are concave pole pieces used in a moving coil galvanometer?
Answer: A moving coil galvanometer uses a light rectangular coil suspended in a strong radial magnetic field between concave pole pieces and a soft iron core. Magnetic torque is NBIA and restoring torque is kθ. At equilibrium, NBIA = kθ, so I = kθ/NBA. This proves deflection is proportional to current. For conversion, use shunt S = IgG/(I − Ig) for ammeter and series resistance R = V/Ig − G for voltmeter.
JEE Advanced Paragraph Question 3Why is soft iron core used?
Answer: A moving coil galvanometer uses a light rectangular coil suspended in a strong radial magnetic field between concave pole pieces and a soft iron core. Magnetic torque is NBIA and restoring torque is kθ. At equilibrium, NBIA = kθ, so I = kθ/NBA. This proves deflection is proportional to current. For conversion, use shunt S = IgG/(I − Ig) for ammeter and series resistance R = V/Ig − G for voltmeter.
JEE Advanced Paragraph Question 4Derive I = kθ/NBA for a moving coil galvanometer.
Answer: A moving coil galvanometer uses a light rectangular coil suspended in a strong radial magnetic field between concave pole pieces and a soft iron core. Magnetic torque is NBIA and restoring torque is kθ. At equilibrium, NBIA = kθ, so I = kθ/NBA. This proves deflection is proportional to current. For conversion, use shunt S = IgG/(I − Ig) for ammeter and series resistance R = V/Ig − G for voltmeter.
JEE Advanced Paragraph Question 5Define current sensitivity and derive its expression.
Answer: A moving coil galvanometer uses a light rectangular coil suspended in a strong radial magnetic field between concave pole pieces and a soft iron core. Magnetic torque is NBIA and restoring torque is kθ. At equilibrium, NBIA = kθ, so I = kθ/NBA. This proves deflection is proportional to current. For conversion, use shunt S = IgG/(I − Ig) for ammeter and series resistance R = V/Ig − G for voltmeter.
JEE Advanced Paragraph Question 6Define voltage sensitivity and derive its expression.
Answer: A moving coil galvanometer uses a light rectangular coil suspended in a strong radial magnetic field between concave pole pieces and a soft iron core. Magnetic torque is NBIA and restoring torque is kθ. At equilibrium, NBIA = kθ, so I = kθ/NBA. This proves deflection is proportional to current. For conversion, use shunt S = IgG/(I − Ig) for ammeter and series resistance R = V/Ig − G for voltmeter.
JEE Advanced Paragraph Question 7Define figure of merit and explain its significance.
Answer: A moving coil galvanometer uses a light rectangular coil suspended in a strong radial magnetic field between concave pole pieces and a soft iron core. Magnetic torque is NBIA and restoring torque is kθ. At equilibrium, NBIA = kθ, so I = kθ/NBA. This proves deflection is proportional to current. For conversion, use shunt S = IgG/(I − Ig) for ammeter and series resistance R = V/Ig − G for voltmeter.
JEE Advanced Paragraph Question 8How is a galvanometer converted into an ammeter?
Answer: A moving coil galvanometer uses a light rectangular coil suspended in a strong radial magnetic field between concave pole pieces and a soft iron core. Magnetic torque is NBIA and restoring torque is kθ. At equilibrium, NBIA = kθ, so I = kθ/NBA. This proves deflection is proportional to current. For conversion, use shunt S = IgG/(I − Ig) for ammeter and series resistance R = V/Ig − G for voltmeter.
JEE Advanced Paragraph Question 9How is a galvanometer converted into a voltmeter?
Answer: A moving coil galvanometer uses a light rectangular coil suspended in a strong radial magnetic field between concave pole pieces and a soft iron core. Magnetic torque is NBIA and restoring torque is kθ. At equilibrium, NBIA = kθ, so I = kθ/NBA. This proves deflection is proportional to current. For conversion, use shunt S = IgG/(I − Ig) for ammeter and series resistance R = V/Ig − G for voltmeter.
JEE Advanced Paragraph Question 10Why is moving coil galvanometer mainly suitable for DC?
Answer: A moving coil galvanometer uses a light rectangular coil suspended in a strong radial magnetic field between concave pole pieces and a soft iron core. Magnetic torque is NBIA and restoring torque is kθ. At equilibrium, NBIA = kθ, so I = kθ/NBA. This proves deflection is proportional to current. For conversion, use shunt S = IgG/(I − Ig) for ammeter and series resistance R = V/Ig − G for voltmeter.

E. IB Physics Questions

IB Question 1Explain construction of moving coil galvanometer.
Answer: A moving coil galvanometer uses a light rectangular coil suspended in a strong radial magnetic field between concave pole pieces and a soft iron core. Magnetic torque is NBIA and restoring torque is kθ. At equilibrium, NBIA = kθ, so I = kθ/NBA. This proves deflection is proportional to current. For conversion, use shunt S = IgG/(I − Ig) for ammeter and series resistance R = V/Ig − G for voltmeter.
IB Question 2Why are concave pole pieces used in a moving coil galvanometer?
Answer: A moving coil galvanometer uses a light rectangular coil suspended in a strong radial magnetic field between concave pole pieces and a soft iron core. Magnetic torque is NBIA and restoring torque is kθ. At equilibrium, NBIA = kθ, so I = kθ/NBA. This proves deflection is proportional to current. For conversion, use shunt S = IgG/(I − Ig) for ammeter and series resistance R = V/Ig − G for voltmeter.
IB Question 3Why is soft iron core used?
Answer: A moving coil galvanometer uses a light rectangular coil suspended in a strong radial magnetic field between concave pole pieces and a soft iron core. Magnetic torque is NBIA and restoring torque is kθ. At equilibrium, NBIA = kθ, so I = kθ/NBA. This proves deflection is proportional to current. For conversion, use shunt S = IgG/(I − Ig) for ammeter and series resistance R = V/Ig − G for voltmeter.
IB Question 4Derive I = kθ/NBA for a moving coil galvanometer.
Answer: A moving coil galvanometer uses a light rectangular coil suspended in a strong radial magnetic field between concave pole pieces and a soft iron core. Magnetic torque is NBIA and restoring torque is kθ. At equilibrium, NBIA = kθ, so I = kθ/NBA. This proves deflection is proportional to current. For conversion, use shunt S = IgG/(I − Ig) for ammeter and series resistance R = V/Ig − G for voltmeter.
IB Question 5Define current sensitivity and derive its expression.
Answer: A moving coil galvanometer uses a light rectangular coil suspended in a strong radial magnetic field between concave pole pieces and a soft iron core. Magnetic torque is NBIA and restoring torque is kθ. At equilibrium, NBIA = kθ, so I = kθ/NBA. This proves deflection is proportional to current. For conversion, use shunt S = IgG/(I − Ig) for ammeter and series resistance R = V/Ig − G for voltmeter.
IB Question 6Define voltage sensitivity and derive its expression.
Answer: A moving coil galvanometer uses a light rectangular coil suspended in a strong radial magnetic field between concave pole pieces and a soft iron core. Magnetic torque is NBIA and restoring torque is kθ. At equilibrium, NBIA = kθ, so I = kθ/NBA. This proves deflection is proportional to current. For conversion, use shunt S = IgG/(I − Ig) for ammeter and series resistance R = V/Ig − G for voltmeter.
IB Question 7Define figure of merit and explain its significance.
Answer: A moving coil galvanometer uses a light rectangular coil suspended in a strong radial magnetic field between concave pole pieces and a soft iron core. Magnetic torque is NBIA and restoring torque is kθ. At equilibrium, NBIA = kθ, so I = kθ/NBA. This proves deflection is proportional to current. For conversion, use shunt S = IgG/(I − Ig) for ammeter and series resistance R = V/Ig − G for voltmeter.
IB Question 8How is a galvanometer converted into an ammeter?
Answer: A moving coil galvanometer uses a light rectangular coil suspended in a strong radial magnetic field between concave pole pieces and a soft iron core. Magnetic torque is NBIA and restoring torque is kθ. At equilibrium, NBIA = kθ, so I = kθ/NBA. This proves deflection is proportional to current. For conversion, use shunt S = IgG/(I − Ig) for ammeter and series resistance R = V/Ig − G for voltmeter.
IB Question 9How is a galvanometer converted into a voltmeter?
Answer: A moving coil galvanometer uses a light rectangular coil suspended in a strong radial magnetic field between concave pole pieces and a soft iron core. Magnetic torque is NBIA and restoring torque is kθ. At equilibrium, NBIA = kθ, so I = kθ/NBA. This proves deflection is proportional to current. For conversion, use shunt S = IgG/(I − Ig) for ammeter and series resistance R = V/Ig − G for voltmeter.
IB Question 10Why is moving coil galvanometer mainly suitable for DC?
Answer: A moving coil galvanometer uses a light rectangular coil suspended in a strong radial magnetic field between concave pole pieces and a soft iron core. Magnetic torque is NBIA and restoring torque is kθ. At equilibrium, NBIA = kθ, so I = kθ/NBA. This proves deflection is proportional to current. For conversion, use shunt S = IgG/(I − Ig) for ammeter and series resistance R = V/Ig − G for voltmeter.
IB Question 11Explain construction of moving coil galvanometer.
Answer: A moving coil galvanometer uses a light rectangular coil suspended in a strong radial magnetic field between concave pole pieces and a soft iron core. Magnetic torque is NBIA and restoring torque is kθ. At equilibrium, NBIA = kθ, so I = kθ/NBA. This proves deflection is proportional to current. For conversion, use shunt S = IgG/(I − Ig) for ammeter and series resistance R = V/Ig − G for voltmeter.
IB Question 12Why are concave pole pieces used in a moving coil galvanometer?
Answer: A moving coil galvanometer uses a light rectangular coil suspended in a strong radial magnetic field between concave pole pieces and a soft iron core. Magnetic torque is NBIA and restoring torque is kθ. At equilibrium, NBIA = kθ, so I = kθ/NBA. This proves deflection is proportional to current. For conversion, use shunt S = IgG/(I − Ig) for ammeter and series resistance R = V/Ig − G for voltmeter.
IB Question 13Why is soft iron core used?
Answer: A moving coil galvanometer uses a light rectangular coil suspended in a strong radial magnetic field between concave pole pieces and a soft iron core. Magnetic torque is NBIA and restoring torque is kθ. At equilibrium, NBIA = kθ, so I = kθ/NBA. This proves deflection is proportional to current. For conversion, use shunt S = IgG/(I − Ig) for ammeter and series resistance R = V/Ig − G for voltmeter.
IB Question 14Derive I = kθ/NBA for a moving coil galvanometer.
Answer: A moving coil galvanometer uses a light rectangular coil suspended in a strong radial magnetic field between concave pole pieces and a soft iron core. Magnetic torque is NBIA and restoring torque is kθ. At equilibrium, NBIA = kθ, so I = kθ/NBA. This proves deflection is proportional to current. For conversion, use shunt S = IgG/(I − Ig) for ammeter and series resistance R = V/Ig − G for voltmeter.
IB Question 15Define current sensitivity and derive its expression.
Answer: A moving coil galvanometer uses a light rectangular coil suspended in a strong radial magnetic field between concave pole pieces and a soft iron core. Magnetic torque is NBIA and restoring torque is kθ. At equilibrium, NBIA = kθ, so I = kθ/NBA. This proves deflection is proportional to current. For conversion, use shunt S = IgG/(I − Ig) for ammeter and series resistance R = V/Ig − G for voltmeter.
IB Question 16Define voltage sensitivity and derive its expression.
Answer: A moving coil galvanometer uses a light rectangular coil suspended in a strong radial magnetic field between concave pole pieces and a soft iron core. Magnetic torque is NBIA and restoring torque is kθ. At equilibrium, NBIA = kθ, so I = kθ/NBA. This proves deflection is proportional to current. For conversion, use shunt S = IgG/(I − Ig) for ammeter and series resistance R = V/Ig − G for voltmeter.
IB Question 17Define figure of merit and explain its significance.
Answer: A moving coil galvanometer uses a light rectangular coil suspended in a strong radial magnetic field between concave pole pieces and a soft iron core. Magnetic torque is NBIA and restoring torque is kθ. At equilibrium, NBIA = kθ, so I = kθ/NBA. This proves deflection is proportional to current. For conversion, use shunt S = IgG/(I − Ig) for ammeter and series resistance R = V/Ig − G for voltmeter.
IB Question 18How is a galvanometer converted into an ammeter?
Answer: A moving coil galvanometer uses a light rectangular coil suspended in a strong radial magnetic field between concave pole pieces and a soft iron core. Magnetic torque is NBIA and restoring torque is kθ. At equilibrium, NBIA = kθ, so I = kθ/NBA. This proves deflection is proportional to current. For conversion, use shunt S = IgG/(I − Ig) for ammeter and series resistance R = V/Ig − G for voltmeter.
IB Question 19How is a galvanometer converted into a voltmeter?
Answer: A moving coil galvanometer uses a light rectangular coil suspended in a strong radial magnetic field between concave pole pieces and a soft iron core. Magnetic torque is NBIA and restoring torque is kθ. At equilibrium, NBIA = kθ, so I = kθ/NBA. This proves deflection is proportional to current. For conversion, use shunt S = IgG/(I − Ig) for ammeter and series resistance R = V/Ig − G for voltmeter.
IB Question 20Why is moving coil galvanometer mainly suitable for DC?
Answer: A moving coil galvanometer uses a light rectangular coil suspended in a strong radial magnetic field between concave pole pieces and a soft iron core. Magnetic torque is NBIA and restoring torque is kθ. At equilibrium, NBIA = kθ, so I = kθ/NBA. This proves deflection is proportional to current. For conversion, use shunt S = IgG/(I − Ig) for ammeter and series resistance R = V/Ig − G for voltmeter.
IB Question 21Explain construction of moving coil galvanometer.
Answer: A moving coil galvanometer uses a light rectangular coil suspended in a strong radial magnetic field between concave pole pieces and a soft iron core. Magnetic torque is NBIA and restoring torque is kθ. At equilibrium, NBIA = kθ, so I = kθ/NBA. This proves deflection is proportional to current. For conversion, use shunt S = IgG/(I − Ig) for ammeter and series resistance R = V/Ig − G for voltmeter.
IB Question 22Why are concave pole pieces used in a moving coil galvanometer?
Answer: A moving coil galvanometer uses a light rectangular coil suspended in a strong radial magnetic field between concave pole pieces and a soft iron core. Magnetic torque is NBIA and restoring torque is kθ. At equilibrium, NBIA = kθ, so I = kθ/NBA. This proves deflection is proportional to current. For conversion, use shunt S = IgG/(I − Ig) for ammeter and series resistance R = V/Ig − G for voltmeter.
IB Question 23Why is soft iron core used?
Answer: A moving coil galvanometer uses a light rectangular coil suspended in a strong radial magnetic field between concave pole pieces and a soft iron core. Magnetic torque is NBIA and restoring torque is kθ. At equilibrium, NBIA = kθ, so I = kθ/NBA. This proves deflection is proportional to current. For conversion, use shunt S = IgG/(I − Ig) for ammeter and series resistance R = V/Ig − G for voltmeter.
IB Question 24Derive I = kθ/NBA for a moving coil galvanometer.
Answer: A moving coil galvanometer uses a light rectangular coil suspended in a strong radial magnetic field between concave pole pieces and a soft iron core. Magnetic torque is NBIA and restoring torque is kθ. At equilibrium, NBIA = kθ, so I = kθ/NBA. This proves deflection is proportional to current. For conversion, use shunt S = IgG/(I − Ig) for ammeter and series resistance R = V/Ig − G for voltmeter.
IB Question 25Define current sensitivity and derive its expression.
Answer: A moving coil galvanometer uses a light rectangular coil suspended in a strong radial magnetic field between concave pole pieces and a soft iron core. Magnetic torque is NBIA and restoring torque is kθ. At equilibrium, NBIA = kθ, so I = kθ/NBA. This proves deflection is proportional to current. For conversion, use shunt S = IgG/(I − Ig) for ammeter and series resistance R = V/Ig − G for voltmeter.

F. ICSE Physics Questions

ICSE Question 1Explain construction of moving coil galvanometer.
Answer: A moving coil galvanometer uses a light rectangular coil suspended in a strong radial magnetic field between concave pole pieces and a soft iron core. Magnetic torque is NBIA and restoring torque is kθ. At equilibrium, NBIA = kθ, so I = kθ/NBA. This proves deflection is proportional to current. For conversion, use shunt S = IgG/(I − Ig) for ammeter and series resistance R = V/Ig − G for voltmeter.
ICSE Question 2Why are concave pole pieces used in a moving coil galvanometer?
Answer: A moving coil galvanometer uses a light rectangular coil suspended in a strong radial magnetic field between concave pole pieces and a soft iron core. Magnetic torque is NBIA and restoring torque is kθ. At equilibrium, NBIA = kθ, so I = kθ/NBA. This proves deflection is proportional to current. For conversion, use shunt S = IgG/(I − Ig) for ammeter and series resistance R = V/Ig − G for voltmeter.
ICSE Question 3Why is soft iron core used?
Answer: A moving coil galvanometer uses a light rectangular coil suspended in a strong radial magnetic field between concave pole pieces and a soft iron core. Magnetic torque is NBIA and restoring torque is kθ. At equilibrium, NBIA = kθ, so I = kθ/NBA. This proves deflection is proportional to current. For conversion, use shunt S = IgG/(I − Ig) for ammeter and series resistance R = V/Ig − G for voltmeter.
ICSE Question 4Derive I = kθ/NBA for a moving coil galvanometer.
Answer: A moving coil galvanometer uses a light rectangular coil suspended in a strong radial magnetic field between concave pole pieces and a soft iron core. Magnetic torque is NBIA and restoring torque is kθ. At equilibrium, NBIA = kθ, so I = kθ/NBA. This proves deflection is proportional to current. For conversion, use shunt S = IgG/(I − Ig) for ammeter and series resistance R = V/Ig − G for voltmeter.
ICSE Question 5Define current sensitivity and derive its expression.
Answer: A moving coil galvanometer uses a light rectangular coil suspended in a strong radial magnetic field between concave pole pieces and a soft iron core. Magnetic torque is NBIA and restoring torque is kθ. At equilibrium, NBIA = kθ, so I = kθ/NBA. This proves deflection is proportional to current. For conversion, use shunt S = IgG/(I − Ig) for ammeter and series resistance R = V/Ig − G for voltmeter.
ICSE Question 6Define voltage sensitivity and derive its expression.
Answer: A moving coil galvanometer uses a light rectangular coil suspended in a strong radial magnetic field between concave pole pieces and a soft iron core. Magnetic torque is NBIA and restoring torque is kθ. At equilibrium, NBIA = kθ, so I = kθ/NBA. This proves deflection is proportional to current. For conversion, use shunt S = IgG/(I − Ig) for ammeter and series resistance R = V/Ig − G for voltmeter.
ICSE Question 7Define figure of merit and explain its significance.
Answer: A moving coil galvanometer uses a light rectangular coil suspended in a strong radial magnetic field between concave pole pieces and a soft iron core. Magnetic torque is NBIA and restoring torque is kθ. At equilibrium, NBIA = kθ, so I = kθ/NBA. This proves deflection is proportional to current. For conversion, use shunt S = IgG/(I − Ig) for ammeter and series resistance R = V/Ig − G for voltmeter.
ICSE Question 8How is a galvanometer converted into an ammeter?
Answer: A moving coil galvanometer uses a light rectangular coil suspended in a strong radial magnetic field between concave pole pieces and a soft iron core. Magnetic torque is NBIA and restoring torque is kθ. At equilibrium, NBIA = kθ, so I = kθ/NBA. This proves deflection is proportional to current. For conversion, use shunt S = IgG/(I − Ig) for ammeter and series resistance R = V/Ig − G for voltmeter.
ICSE Question 9How is a galvanometer converted into a voltmeter?
Answer: A moving coil galvanometer uses a light rectangular coil suspended in a strong radial magnetic field between concave pole pieces and a soft iron core. Magnetic torque is NBIA and restoring torque is kθ. At equilibrium, NBIA = kθ, so I = kθ/NBA. This proves deflection is proportional to current. For conversion, use shunt S = IgG/(I − Ig) for ammeter and series resistance R = V/Ig − G for voltmeter.
ICSE Question 10Why is moving coil galvanometer mainly suitable for DC?
Answer: A moving coil galvanometer uses a light rectangular coil suspended in a strong radial magnetic field between concave pole pieces and a soft iron core. Magnetic torque is NBIA and restoring torque is kθ. At equilibrium, NBIA = kθ, so I = kθ/NBA. This proves deflection is proportional to current. For conversion, use shunt S = IgG/(I − Ig) for ammeter and series resistance R = V/Ig − G for voltmeter.
ICSE Question 11Explain construction of moving coil galvanometer.
Answer: A moving coil galvanometer uses a light rectangular coil suspended in a strong radial magnetic field between concave pole pieces and a soft iron core. Magnetic torque is NBIA and restoring torque is kθ. At equilibrium, NBIA = kθ, so I = kθ/NBA. This proves deflection is proportional to current. For conversion, use shunt S = IgG/(I − Ig) for ammeter and series resistance R = V/Ig − G for voltmeter.
ICSE Question 12Why are concave pole pieces used in a moving coil galvanometer?
Answer: A moving coil galvanometer uses a light rectangular coil suspended in a strong radial magnetic field between concave pole pieces and a soft iron core. Magnetic torque is NBIA and restoring torque is kθ. At equilibrium, NBIA = kθ, so I = kθ/NBA. This proves deflection is proportional to current. For conversion, use shunt S = IgG/(I − Ig) for ammeter and series resistance R = V/Ig − G for voltmeter.
ICSE Question 13Why is soft iron core used?
Answer: A moving coil galvanometer uses a light rectangular coil suspended in a strong radial magnetic field between concave pole pieces and a soft iron core. Magnetic torque is NBIA and restoring torque is kθ. At equilibrium, NBIA = kθ, so I = kθ/NBA. This proves deflection is proportional to current. For conversion, use shunt S = IgG/(I − Ig) for ammeter and series resistance R = V/Ig − G for voltmeter.
ICSE Question 14Derive I = kθ/NBA for a moving coil galvanometer.
Answer: A moving coil galvanometer uses a light rectangular coil suspended in a strong radial magnetic field between concave pole pieces and a soft iron core. Magnetic torque is NBIA and restoring torque is kθ. At equilibrium, NBIA = kθ, so I = kθ/NBA. This proves deflection is proportional to current. For conversion, use shunt S = IgG/(I − Ig) for ammeter and series resistance R = V/Ig − G for voltmeter.
ICSE Question 15Define current sensitivity and derive its expression.
Answer: A moving coil galvanometer uses a light rectangular coil suspended in a strong radial magnetic field between concave pole pieces and a soft iron core. Magnetic torque is NBIA and restoring torque is kθ. At equilibrium, NBIA = kθ, so I = kθ/NBA. This proves deflection is proportional to current. For conversion, use shunt S = IgG/(I − Ig) for ammeter and series resistance R = V/Ig − G for voltmeter.
ICSE Question 16Define voltage sensitivity and derive its expression.
Answer: A moving coil galvanometer uses a light rectangular coil suspended in a strong radial magnetic field between concave pole pieces and a soft iron core. Magnetic torque is NBIA and restoring torque is kθ. At equilibrium, NBIA = kθ, so I = kθ/NBA. This proves deflection is proportional to current. For conversion, use shunt S = IgG/(I − Ig) for ammeter and series resistance R = V/Ig − G for voltmeter.
ICSE Question 17Define figure of merit and explain its significance.
Answer: A moving coil galvanometer uses a light rectangular coil suspended in a strong radial magnetic field between concave pole pieces and a soft iron core. Magnetic torque is NBIA and restoring torque is kθ. At equilibrium, NBIA = kθ, so I = kθ/NBA. This proves deflection is proportional to current. For conversion, use shunt S = IgG/(I − Ig) for ammeter and series resistance R = V/Ig − G for voltmeter.
ICSE Question 18How is a galvanometer converted into an ammeter?
Answer: A moving coil galvanometer uses a light rectangular coil suspended in a strong radial magnetic field between concave pole pieces and a soft iron core. Magnetic torque is NBIA and restoring torque is kθ. At equilibrium, NBIA = kθ, so I = kθ/NBA. This proves deflection is proportional to current. For conversion, use shunt S = IgG/(I − Ig) for ammeter and series resistance R = V/Ig − G for voltmeter.
ICSE Question 19How is a galvanometer converted into a voltmeter?
Answer: A moving coil galvanometer uses a light rectangular coil suspended in a strong radial magnetic field between concave pole pieces and a soft iron core. Magnetic torque is NBIA and restoring torque is kθ. At equilibrium, NBIA = kθ, so I = kθ/NBA. This proves deflection is proportional to current. For conversion, use shunt S = IgG/(I − Ig) for ammeter and series resistance R = V/Ig − G for voltmeter.
ICSE Question 20Why is moving coil galvanometer mainly suitable for DC?
Answer: A moving coil galvanometer uses a light rectangular coil suspended in a strong radial magnetic field between concave pole pieces and a soft iron core. Magnetic torque is NBIA and restoring torque is kθ. At equilibrium, NBIA = kθ, so I = kθ/NBA. This proves deflection is proportional to current. For conversion, use shunt S = IgG/(I − Ig) for ammeter and series resistance R = V/Ig − G for voltmeter.
ICSE Question 21Explain construction of moving coil galvanometer.
Answer: A moving coil galvanometer uses a light rectangular coil suspended in a strong radial magnetic field between concave pole pieces and a soft iron core. Magnetic torque is NBIA and restoring torque is kθ. At equilibrium, NBIA = kθ, so I = kθ/NBA. This proves deflection is proportional to current. For conversion, use shunt S = IgG/(I − Ig) for ammeter and series resistance R = V/Ig − G for voltmeter.
ICSE Question 22Why are concave pole pieces used in a moving coil galvanometer?
Answer: A moving coil galvanometer uses a light rectangular coil suspended in a strong radial magnetic field between concave pole pieces and a soft iron core. Magnetic torque is NBIA and restoring torque is kθ. At equilibrium, NBIA = kθ, so I = kθ/NBA. This proves deflection is proportional to current. For conversion, use shunt S = IgG/(I − Ig) for ammeter and series resistance R = V/Ig − G for voltmeter.
ICSE Question 23Why is soft iron core used?
Answer: A moving coil galvanometer uses a light rectangular coil suspended in a strong radial magnetic field between concave pole pieces and a soft iron core. Magnetic torque is NBIA and restoring torque is kθ. At equilibrium, NBIA = kθ, so I = kθ/NBA. This proves deflection is proportional to current. For conversion, use shunt S = IgG/(I − Ig) for ammeter and series resistance R = V/Ig − G for voltmeter.
ICSE Question 24Derive I = kθ/NBA for a moving coil galvanometer.
Answer: A moving coil galvanometer uses a light rectangular coil suspended in a strong radial magnetic field between concave pole pieces and a soft iron core. Magnetic torque is NBIA and restoring torque is kθ. At equilibrium, NBIA = kθ, so I = kθ/NBA. This proves deflection is proportional to current. For conversion, use shunt S = IgG/(I − Ig) for ammeter and series resistance R = V/Ig − G for voltmeter.
ICSE Question 25Define current sensitivity and derive its expression.
Answer: A moving coil galvanometer uses a light rectangular coil suspended in a strong radial magnetic field between concave pole pieces and a soft iron core. Magnetic torque is NBIA and restoring torque is kθ. At equilibrium, NBIA = kθ, so I = kθ/NBA. This proves deflection is proportional to current. For conversion, use shunt S = IgG/(I − Ig) for ammeter and series resistance R = V/Ig − G for voltmeter.

G. IGCSE Physics Questions

IGCSE Question 1Explain construction of moving coil galvanometer.
Answer: A moving coil galvanometer uses a light rectangular coil suspended in a strong radial magnetic field between concave pole pieces and a soft iron core. Magnetic torque is NBIA and restoring torque is kθ. At equilibrium, NBIA = kθ, so I = kθ/NBA. This proves deflection is proportional to current. For conversion, use shunt S = IgG/(I − Ig) for ammeter and series resistance R = V/Ig − G for voltmeter.
IGCSE Question 2Why are concave pole pieces used in a moving coil galvanometer?
Answer: A moving coil galvanometer uses a light rectangular coil suspended in a strong radial magnetic field between concave pole pieces and a soft iron core. Magnetic torque is NBIA and restoring torque is kθ. At equilibrium, NBIA = kθ, so I = kθ/NBA. This proves deflection is proportional to current. For conversion, use shunt S = IgG/(I − Ig) for ammeter and series resistance R = V/Ig − G for voltmeter.
IGCSE Question 3Why is soft iron core used?
Answer: A moving coil galvanometer uses a light rectangular coil suspended in a strong radial magnetic field between concave pole pieces and a soft iron core. Magnetic torque is NBIA and restoring torque is kθ. At equilibrium, NBIA = kθ, so I = kθ/NBA. This proves deflection is proportional to current. For conversion, use shunt S = IgG/(I − Ig) for ammeter and series resistance R = V/Ig − G for voltmeter.
IGCSE Question 4Derive I = kθ/NBA for a moving coil galvanometer.
Answer: A moving coil galvanometer uses a light rectangular coil suspended in a strong radial magnetic field between concave pole pieces and a soft iron core. Magnetic torque is NBIA and restoring torque is kθ. At equilibrium, NBIA = kθ, so I = kθ/NBA. This proves deflection is proportional to current. For conversion, use shunt S = IgG/(I − Ig) for ammeter and series resistance R = V/Ig − G for voltmeter.
IGCSE Question 5Define current sensitivity and derive its expression.
Answer: A moving coil galvanometer uses a light rectangular coil suspended in a strong radial magnetic field between concave pole pieces and a soft iron core. Magnetic torque is NBIA and restoring torque is kθ. At equilibrium, NBIA = kθ, so I = kθ/NBA. This proves deflection is proportional to current. For conversion, use shunt S = IgG/(I − Ig) for ammeter and series resistance R = V/Ig − G for voltmeter.
IGCSE Question 6Define voltage sensitivity and derive its expression.
Answer: A moving coil galvanometer uses a light rectangular coil suspended in a strong radial magnetic field between concave pole pieces and a soft iron core. Magnetic torque is NBIA and restoring torque is kθ. At equilibrium, NBIA = kθ, so I = kθ/NBA. This proves deflection is proportional to current. For conversion, use shunt S = IgG/(I − Ig) for ammeter and series resistance R = V/Ig − G for voltmeter.
IGCSE Question 7Define figure of merit and explain its significance.
Answer: A moving coil galvanometer uses a light rectangular coil suspended in a strong radial magnetic field between concave pole pieces and a soft iron core. Magnetic torque is NBIA and restoring torque is kθ. At equilibrium, NBIA = kθ, so I = kθ/NBA. This proves deflection is proportional to current. For conversion, use shunt S = IgG/(I − Ig) for ammeter and series resistance R = V/Ig − G for voltmeter.
IGCSE Question 8How is a galvanometer converted into an ammeter?
Answer: A moving coil galvanometer uses a light rectangular coil suspended in a strong radial magnetic field between concave pole pieces and a soft iron core. Magnetic torque is NBIA and restoring torque is kθ. At equilibrium, NBIA = kθ, so I = kθ/NBA. This proves deflection is proportional to current. For conversion, use shunt S = IgG/(I − Ig) for ammeter and series resistance R = V/Ig − G for voltmeter.
IGCSE Question 9How is a galvanometer converted into a voltmeter?
Answer: A moving coil galvanometer uses a light rectangular coil suspended in a strong radial magnetic field between concave pole pieces and a soft iron core. Magnetic torque is NBIA and restoring torque is kθ. At equilibrium, NBIA = kθ, so I = kθ/NBA. This proves deflection is proportional to current. For conversion, use shunt S = IgG/(I − Ig) for ammeter and series resistance R = V/Ig − G for voltmeter.
IGCSE Question 10Why is moving coil galvanometer mainly suitable for DC?
Answer: A moving coil galvanometer uses a light rectangular coil suspended in a strong radial magnetic field between concave pole pieces and a soft iron core. Magnetic torque is NBIA and restoring torque is kθ. At equilibrium, NBIA = kθ, so I = kθ/NBA. This proves deflection is proportional to current. For conversion, use shunt S = IgG/(I − Ig) for ammeter and series resistance R = V/Ig − G for voltmeter.
IGCSE Question 11Explain construction of moving coil galvanometer.
Answer: A moving coil galvanometer uses a light rectangular coil suspended in a strong radial magnetic field between concave pole pieces and a soft iron core. Magnetic torque is NBIA and restoring torque is kθ. At equilibrium, NBIA = kθ, so I = kθ/NBA. This proves deflection is proportional to current. For conversion, use shunt S = IgG/(I − Ig) for ammeter and series resistance R = V/Ig − G for voltmeter.
IGCSE Question 12Why are concave pole pieces used in a moving coil galvanometer?
Answer: A moving coil galvanometer uses a light rectangular coil suspended in a strong radial magnetic field between concave pole pieces and a soft iron core. Magnetic torque is NBIA and restoring torque is kθ. At equilibrium, NBIA = kθ, so I = kθ/NBA. This proves deflection is proportional to current. For conversion, use shunt S = IgG/(I − Ig) for ammeter and series resistance R = V/Ig − G for voltmeter.
IGCSE Question 13Why is soft iron core used?
Answer: A moving coil galvanometer uses a light rectangular coil suspended in a strong radial magnetic field between concave pole pieces and a soft iron core. Magnetic torque is NBIA and restoring torque is kθ. At equilibrium, NBIA = kθ, so I = kθ/NBA. This proves deflection is proportional to current. For conversion, use shunt S = IgG/(I − Ig) for ammeter and series resistance R = V/Ig − G for voltmeter.
IGCSE Question 14Derive I = kθ/NBA for a moving coil galvanometer.
Answer: A moving coil galvanometer uses a light rectangular coil suspended in a strong radial magnetic field between concave pole pieces and a soft iron core. Magnetic torque is NBIA and restoring torque is kθ. At equilibrium, NBIA = kθ, so I = kθ/NBA. This proves deflection is proportional to current. For conversion, use shunt S = IgG/(I − Ig) for ammeter and series resistance R = V/Ig − G for voltmeter.
IGCSE Question 15Define current sensitivity and derive its expression.
Answer: A moving coil galvanometer uses a light rectangular coil suspended in a strong radial magnetic field between concave pole pieces and a soft iron core. Magnetic torque is NBIA and restoring torque is kθ. At equilibrium, NBIA = kθ, so I = kθ/NBA. This proves deflection is proportional to current. For conversion, use shunt S = IgG/(I − Ig) for ammeter and series resistance R = V/Ig − G for voltmeter.
IGCSE Question 16Define voltage sensitivity and derive its expression.
Answer: A moving coil galvanometer uses a light rectangular coil suspended in a strong radial magnetic field between concave pole pieces and a soft iron core. Magnetic torque is NBIA and restoring torque is kθ. At equilibrium, NBIA = kθ, so I = kθ/NBA. This proves deflection is proportional to current. For conversion, use shunt S = IgG/(I − Ig) for ammeter and series resistance R = V/Ig − G for voltmeter.
IGCSE Question 17Define figure of merit and explain its significance.
Answer: A moving coil galvanometer uses a light rectangular coil suspended in a strong radial magnetic field between concave pole pieces and a soft iron core. Magnetic torque is NBIA and restoring torque is kθ. At equilibrium, NBIA = kθ, so I = kθ/NBA. This proves deflection is proportional to current. For conversion, use shunt S = IgG/(I − Ig) for ammeter and series resistance R = V/Ig − G for voltmeter.
IGCSE Question 18How is a galvanometer converted into an ammeter?
Answer: A moving coil galvanometer uses a light rectangular coil suspended in a strong radial magnetic field between concave pole pieces and a soft iron core. Magnetic torque is NBIA and restoring torque is kθ. At equilibrium, NBIA = kθ, so I = kθ/NBA. This proves deflection is proportional to current. For conversion, use shunt S = IgG/(I − Ig) for ammeter and series resistance R = V/Ig − G for voltmeter.
IGCSE Question 19How is a galvanometer converted into a voltmeter?
Answer: A moving coil galvanometer uses a light rectangular coil suspended in a strong radial magnetic field between concave pole pieces and a soft iron core. Magnetic torque is NBIA and restoring torque is kθ. At equilibrium, NBIA = kθ, so I = kθ/NBA. This proves deflection is proportional to current. For conversion, use shunt S = IgG/(I − Ig) for ammeter and series resistance R = V/Ig − G for voltmeter.
IGCSE Question 20Why is moving coil galvanometer mainly suitable for DC?
Answer: A moving coil galvanometer uses a light rectangular coil suspended in a strong radial magnetic field between concave pole pieces and a soft iron core. Magnetic torque is NBIA and restoring torque is kθ. At equilibrium, NBIA = kθ, so I = kθ/NBA. This proves deflection is proportional to current. For conversion, use shunt S = IgG/(I − Ig) for ammeter and series resistance R = V/Ig − G for voltmeter.
IGCSE Question 21Explain construction of moving coil galvanometer.
Answer: A moving coil galvanometer uses a light rectangular coil suspended in a strong radial magnetic field between concave pole pieces and a soft iron core. Magnetic torque is NBIA and restoring torque is kθ. At equilibrium, NBIA = kθ, so I = kθ/NBA. This proves deflection is proportional to current. For conversion, use shunt S = IgG/(I − Ig) for ammeter and series resistance R = V/Ig − G for voltmeter.
IGCSE Question 22Why are concave pole pieces used in a moving coil galvanometer?
Answer: A moving coil galvanometer uses a light rectangular coil suspended in a strong radial magnetic field between concave pole pieces and a soft iron core. Magnetic torque is NBIA and restoring torque is kθ. At equilibrium, NBIA = kθ, so I = kθ/NBA. This proves deflection is proportional to current. For conversion, use shunt S = IgG/(I − Ig) for ammeter and series resistance R = V/Ig − G for voltmeter.
IGCSE Question 23Why is soft iron core used?
Answer: A moving coil galvanometer uses a light rectangular coil suspended in a strong radial magnetic field between concave pole pieces and a soft iron core. Magnetic torque is NBIA and restoring torque is kθ. At equilibrium, NBIA = kθ, so I = kθ/NBA. This proves deflection is proportional to current. For conversion, use shunt S = IgG/(I − Ig) for ammeter and series resistance R = V/Ig − G for voltmeter.
IGCSE Question 24Derive I = kθ/NBA for a moving coil galvanometer.
Answer: A moving coil galvanometer uses a light rectangular coil suspended in a strong radial magnetic field between concave pole pieces and a soft iron core. Magnetic torque is NBIA and restoring torque is kθ. At equilibrium, NBIA = kθ, so I = kθ/NBA. This proves deflection is proportional to current. For conversion, use shunt S = IgG/(I − Ig) for ammeter and series resistance R = V/Ig − G for voltmeter.
IGCSE Question 25Define current sensitivity and derive its expression.
Answer: A moving coil galvanometer uses a light rectangular coil suspended in a strong radial magnetic field between concave pole pieces and a soft iron core. Magnetic torque is NBIA and restoring torque is kθ. At equilibrium, NBIA = kθ, so I = kθ/NBA. This proves deflection is proportional to current. For conversion, use shunt S = IgG/(I − Ig) for ammeter and series resistance R = V/Ig − G for voltmeter.

H. British Curriculum / A-Level Physics

A-Level Question 1Explain construction of moving coil galvanometer.
Answer: A moving coil galvanometer uses a light rectangular coil suspended in a strong radial magnetic field between concave pole pieces and a soft iron core. Magnetic torque is NBIA and restoring torque is kθ. At equilibrium, NBIA = kθ, so I = kθ/NBA. This proves deflection is proportional to current. For conversion, use shunt S = IgG/(I − Ig) for ammeter and series resistance R = V/Ig − G for voltmeter.
A-Level Question 2Why are concave pole pieces used in a moving coil galvanometer?
Answer: A moving coil galvanometer uses a light rectangular coil suspended in a strong radial magnetic field between concave pole pieces and a soft iron core. Magnetic torque is NBIA and restoring torque is kθ. At equilibrium, NBIA = kθ, so I = kθ/NBA. This proves deflection is proportional to current. For conversion, use shunt S = IgG/(I − Ig) for ammeter and series resistance R = V/Ig − G for voltmeter.
A-Level Question 3Why is soft iron core used?
Answer: A moving coil galvanometer uses a light rectangular coil suspended in a strong radial magnetic field between concave pole pieces and a soft iron core. Magnetic torque is NBIA and restoring torque is kθ. At equilibrium, NBIA = kθ, so I = kθ/NBA. This proves deflection is proportional to current. For conversion, use shunt S = IgG/(I − Ig) for ammeter and series resistance R = V/Ig − G for voltmeter.
A-Level Question 4Derive I = kθ/NBA for a moving coil galvanometer.
Answer: A moving coil galvanometer uses a light rectangular coil suspended in a strong radial magnetic field between concave pole pieces and a soft iron core. Magnetic torque is NBIA and restoring torque is kθ. At equilibrium, NBIA = kθ, so I = kθ/NBA. This proves deflection is proportional to current. For conversion, use shunt S = IgG/(I − Ig) for ammeter and series resistance R = V/Ig − G for voltmeter.
A-Level Question 5Define current sensitivity and derive its expression.
Answer: A moving coil galvanometer uses a light rectangular coil suspended in a strong radial magnetic field between concave pole pieces and a soft iron core. Magnetic torque is NBIA and restoring torque is kθ. At equilibrium, NBIA = kθ, so I = kθ/NBA. This proves deflection is proportional to current. For conversion, use shunt S = IgG/(I − Ig) for ammeter and series resistance R = V/Ig − G for voltmeter.
A-Level Question 6Define voltage sensitivity and derive its expression.
Answer: A moving coil galvanometer uses a light rectangular coil suspended in a strong radial magnetic field between concave pole pieces and a soft iron core. Magnetic torque is NBIA and restoring torque is kθ. At equilibrium, NBIA = kθ, so I = kθ/NBA. This proves deflection is proportional to current. For conversion, use shunt S = IgG/(I − Ig) for ammeter and series resistance R = V/Ig − G for voltmeter.
A-Level Question 7Define figure of merit and explain its significance.
Answer: A moving coil galvanometer uses a light rectangular coil suspended in a strong radial magnetic field between concave pole pieces and a soft iron core. Magnetic torque is NBIA and restoring torque is kθ. At equilibrium, NBIA = kθ, so I = kθ/NBA. This proves deflection is proportional to current. For conversion, use shunt S = IgG/(I − Ig) for ammeter and series resistance R = V/Ig − G for voltmeter.
A-Level Question 8How is a galvanometer converted into an ammeter?
Answer: A moving coil galvanometer uses a light rectangular coil suspended in a strong radial magnetic field between concave pole pieces and a soft iron core. Magnetic torque is NBIA and restoring torque is kθ. At equilibrium, NBIA = kθ, so I = kθ/NBA. This proves deflection is proportional to current. For conversion, use shunt S = IgG/(I − Ig) for ammeter and series resistance R = V/Ig − G for voltmeter.
A-Level Question 9How is a galvanometer converted into a voltmeter?
Answer: A moving coil galvanometer uses a light rectangular coil suspended in a strong radial magnetic field between concave pole pieces and a soft iron core. Magnetic torque is NBIA and restoring torque is kθ. At equilibrium, NBIA = kθ, so I = kθ/NBA. This proves deflection is proportional to current. For conversion, use shunt S = IgG/(I − Ig) for ammeter and series resistance R = V/Ig − G for voltmeter.
A-Level Question 10Why is moving coil galvanometer mainly suitable for DC?
Answer: A moving coil galvanometer uses a light rectangular coil suspended in a strong radial magnetic field between concave pole pieces and a soft iron core. Magnetic torque is NBIA and restoring torque is kθ. At equilibrium, NBIA = kθ, so I = kθ/NBA. This proves deflection is proportional to current. For conversion, use shunt S = IgG/(I − Ig) for ammeter and series resistance R = V/Ig − G for voltmeter.
A-Level Question 11Explain construction of moving coil galvanometer.
Answer: A moving coil galvanometer uses a light rectangular coil suspended in a strong radial magnetic field between concave pole pieces and a soft iron core. Magnetic torque is NBIA and restoring torque is kθ. At equilibrium, NBIA = kθ, so I = kθ/NBA. This proves deflection is proportional to current. For conversion, use shunt S = IgG/(I − Ig) for ammeter and series resistance R = V/Ig − G for voltmeter.
A-Level Question 12Why are concave pole pieces used in a moving coil galvanometer?
Answer: A moving coil galvanometer uses a light rectangular coil suspended in a strong radial magnetic field between concave pole pieces and a soft iron core. Magnetic torque is NBIA and restoring torque is kθ. At equilibrium, NBIA = kθ, so I = kθ/NBA. This proves deflection is proportional to current. For conversion, use shunt S = IgG/(I − Ig) for ammeter and series resistance R = V/Ig − G for voltmeter.
A-Level Question 13Why is soft iron core used?
Answer: A moving coil galvanometer uses a light rectangular coil suspended in a strong radial magnetic field between concave pole pieces and a soft iron core. Magnetic torque is NBIA and restoring torque is kθ. At equilibrium, NBIA = kθ, so I = kθ/NBA. This proves deflection is proportional to current. For conversion, use shunt S = IgG/(I − Ig) for ammeter and series resistance R = V/Ig − G for voltmeter.
A-Level Question 14Derive I = kθ/NBA for a moving coil galvanometer.
Answer: A moving coil galvanometer uses a light rectangular coil suspended in a strong radial magnetic field between concave pole pieces and a soft iron core. Magnetic torque is NBIA and restoring torque is kθ. At equilibrium, NBIA = kθ, so I = kθ/NBA. This proves deflection is proportional to current. For conversion, use shunt S = IgG/(I − Ig) for ammeter and series resistance R = V/Ig − G for voltmeter.
A-Level Question 15Define current sensitivity and derive its expression.
Answer: A moving coil galvanometer uses a light rectangular coil suspended in a strong radial magnetic field between concave pole pieces and a soft iron core. Magnetic torque is NBIA and restoring torque is kθ. At equilibrium, NBIA = kθ, so I = kθ/NBA. This proves deflection is proportional to current. For conversion, use shunt S = IgG/(I − Ig) for ammeter and series resistance R = V/Ig − G for voltmeter.
A-Level Question 16Define voltage sensitivity and derive its expression.
Answer: A moving coil galvanometer uses a light rectangular coil suspended in a strong radial magnetic field between concave pole pieces and a soft iron core. Magnetic torque is NBIA and restoring torque is kθ. At equilibrium, NBIA = kθ, so I = kθ/NBA. This proves deflection is proportional to current. For conversion, use shunt S = IgG/(I − Ig) for ammeter and series resistance R = V/Ig − G for voltmeter.
A-Level Question 17Define figure of merit and explain its significance.
Answer: A moving coil galvanometer uses a light rectangular coil suspended in a strong radial magnetic field between concave pole pieces and a soft iron core. Magnetic torque is NBIA and restoring torque is kθ. At equilibrium, NBIA = kθ, so I = kθ/NBA. This proves deflection is proportional to current. For conversion, use shunt S = IgG/(I − Ig) for ammeter and series resistance R = V/Ig − G for voltmeter.
A-Level Question 18How is a galvanometer converted into an ammeter?
Answer: A moving coil galvanometer uses a light rectangular coil suspended in a strong radial magnetic field between concave pole pieces and a soft iron core. Magnetic torque is NBIA and restoring torque is kθ. At equilibrium, NBIA = kθ, so I = kθ/NBA. This proves deflection is proportional to current. For conversion, use shunt S = IgG/(I − Ig) for ammeter and series resistance R = V/Ig − G for voltmeter.
A-Level Question 19How is a galvanometer converted into a voltmeter?
Answer: A moving coil galvanometer uses a light rectangular coil suspended in a strong radial magnetic field between concave pole pieces and a soft iron core. Magnetic torque is NBIA and restoring torque is kθ. At equilibrium, NBIA = kθ, so I = kθ/NBA. This proves deflection is proportional to current. For conversion, use shunt S = IgG/(I − Ig) for ammeter and series resistance R = V/Ig − G for voltmeter.
A-Level Question 20Why is moving coil galvanometer mainly suitable for DC?
Answer: A moving coil galvanometer uses a light rectangular coil suspended in a strong radial magnetic field between concave pole pieces and a soft iron core. Magnetic torque is NBIA and restoring torque is kθ. At equilibrium, NBIA = kθ, so I = kθ/NBA. This proves deflection is proportional to current. For conversion, use shunt S = IgG/(I − Ig) for ammeter and series resistance R = V/Ig − G for voltmeter.
A-Level Question 21Explain construction of moving coil galvanometer.
Answer: A moving coil galvanometer uses a light rectangular coil suspended in a strong radial magnetic field between concave pole pieces and a soft iron core. Magnetic torque is NBIA and restoring torque is kθ. At equilibrium, NBIA = kθ, so I = kθ/NBA. This proves deflection is proportional to current. For conversion, use shunt S = IgG/(I − Ig) for ammeter and series resistance R = V/Ig − G for voltmeter.
A-Level Question 22Why are concave pole pieces used in a moving coil galvanometer?
Answer: A moving coil galvanometer uses a light rectangular coil suspended in a strong radial magnetic field between concave pole pieces and a soft iron core. Magnetic torque is NBIA and restoring torque is kθ. At equilibrium, NBIA = kθ, so I = kθ/NBA. This proves deflection is proportional to current. For conversion, use shunt S = IgG/(I − Ig) for ammeter and series resistance R = V/Ig − G for voltmeter.
A-Level Question 23Why is soft iron core used?
Answer: A moving coil galvanometer uses a light rectangular coil suspended in a strong radial magnetic field between concave pole pieces and a soft iron core. Magnetic torque is NBIA and restoring torque is kθ. At equilibrium, NBIA = kθ, so I = kθ/NBA. This proves deflection is proportional to current. For conversion, use shunt S = IgG/(I − Ig) for ammeter and series resistance R = V/Ig − G for voltmeter.
A-Level Question 24Derive I = kθ/NBA for a moving coil galvanometer.
Answer: A moving coil galvanometer uses a light rectangular coil suspended in a strong radial magnetic field between concave pole pieces and a soft iron core. Magnetic torque is NBIA and restoring torque is kθ. At equilibrium, NBIA = kθ, so I = kθ/NBA. This proves deflection is proportional to current. For conversion, use shunt S = IgG/(I − Ig) for ammeter and series resistance R = V/Ig − G for voltmeter.
A-Level Question 25Define current sensitivity and derive its expression.
Answer: A moving coil galvanometer uses a light rectangular coil suspended in a strong radial magnetic field between concave pole pieces and a soft iron core. Magnetic torque is NBIA and restoring torque is kθ. At equilibrium, NBIA = kθ, so I = kθ/NBA. This proves deflection is proportional to current. For conversion, use shunt S = IgG/(I − Ig) for ammeter and series resistance R = V/Ig − G for voltmeter.

16. Case Study Section

Case Study 1construction and labels
Scenario: A moving coil galvanometer has N turns, coil area A, magnetic field B, galvanometer resistance G and torsional constant k. A current produces angular deflection θ.
Questions: find current, sensitivity, figure of merit or required shunt/series resistance.
Solution: Use NBIA = kθ, I = kθ/NBA, Sᵢ = NBA/k, Sᵥ = NBA/kG, k_g = k/NBA, S = IgG/(I − Ig), and R = V/Ig − G.
Case Study 2radial magnetic field
Scenario: A moving coil galvanometer has N turns, coil area A, magnetic field B, galvanometer resistance G and torsional constant k. A current produces angular deflection θ.
Questions: find current, sensitivity, figure of merit or required shunt/series resistance.
Solution: Use NBIA = kθ, I = kθ/NBA, Sᵢ = NBA/k, Sᵥ = NBA/kG, k_g = k/NBA, S = IgG/(I − Ig), and R = V/Ig − G.
Case Study 3current sensitivity
Scenario: A moving coil galvanometer has N turns, coil area A, magnetic field B, galvanometer resistance G and torsional constant k. A current produces angular deflection θ.
Questions: find current, sensitivity, figure of merit or required shunt/series resistance.
Solution: Use NBIA = kθ, I = kθ/NBA, Sᵢ = NBA/k, Sᵥ = NBA/kG, k_g = k/NBA, S = IgG/(I − Ig), and R = V/Ig − G.
Case Study 4voltage sensitivity
Scenario: A moving coil galvanometer has N turns, coil area A, magnetic field B, galvanometer resistance G and torsional constant k. A current produces angular deflection θ.
Questions: find current, sensitivity, figure of merit or required shunt/series resistance.
Solution: Use NBIA = kθ, I = kθ/NBA, Sᵢ = NBA/k, Sᵥ = NBA/kG, k_g = k/NBA, S = IgG/(I − Ig), and R = V/Ig − G.
Case Study 5figure of merit
Scenario: A moving coil galvanometer has N turns, coil area A, magnetic field B, galvanometer resistance G and torsional constant k. A current produces angular deflection θ.
Questions: find current, sensitivity, figure of merit or required shunt/series resistance.
Solution: Use NBIA = kθ, I = kθ/NBA, Sᵢ = NBA/k, Sᵥ = NBA/kG, k_g = k/NBA, S = IgG/(I − Ig), and R = V/Ig − G.
Case Study 6ammeter conversion
Scenario: A moving coil galvanometer has N turns, coil area A, magnetic field B, galvanometer resistance G and torsional constant k. A current produces angular deflection θ.
Questions: find current, sensitivity, figure of merit or required shunt/series resistance.
Solution: Use NBIA = kθ, I = kθ/NBA, Sᵢ = NBA/k, Sᵥ = NBA/kG, k_g = k/NBA, S = IgG/(I − Ig), and R = V/Ig − G.
Case Study 7voltmeter conversion
Scenario: A moving coil galvanometer has N turns, coil area A, magnetic field B, galvanometer resistance G and torsional constant k. A current produces angular deflection θ.
Questions: find current, sensitivity, figure of merit or required shunt/series resistance.
Solution: Use NBIA = kθ, I = kθ/NBA, Sᵢ = NBA/k, Sᵥ = NBA/kG, k_g = k/NBA, S = IgG/(I − Ig), and R = V/Ig − G.
Case Study 8torque balance
Scenario: A moving coil galvanometer has N turns, coil area A, magnetic field B, galvanometer resistance G and torsional constant k. A current produces angular deflection θ.
Questions: find current, sensitivity, figure of merit or required shunt/series resistance.
Solution: Use NBIA = kθ, I = kθ/NBA, Sᵢ = NBA/k, Sᵥ = NBA/kG, k_g = k/NBA, S = IgG/(I − Ig), and R = V/Ig − G.
Case Study 9instrument damage
Scenario: A moving coil galvanometer has N turns, coil area A, magnetic field B, galvanometer resistance G and torsional constant k. A current produces angular deflection θ.
Questions: find current, sensitivity, figure of merit or required shunt/series resistance.
Solution: Use NBIA = kθ, I = kθ/NBA, Sᵢ = NBA/k, Sᵥ = NBA/kG, k_g = k/NBA, S = IgG/(I − Ig), and R = V/Ig − G.
Case Study 10experimental current measurement
Scenario: A moving coil galvanometer has N turns, coil area A, magnetic field B, galvanometer resistance G and torsional constant k. A current produces angular deflection θ.
Questions: find current, sensitivity, figure of merit or required shunt/series resistance.
Solution: Use NBIA = kθ, I = kθ/NBA, Sᵢ = NBA/k, Sᵥ = NBA/kG, k_g = k/NBA, S = IgG/(I − Ig), and R = V/Ig − G.
Case Study 11construction and labels
Scenario: A moving coil galvanometer has N turns, coil area A, magnetic field B, galvanometer resistance G and torsional constant k. A current produces angular deflection θ.
Questions: find current, sensitivity, figure of merit or required shunt/series resistance.
Solution: Use NBIA = kθ, I = kθ/NBA, Sᵢ = NBA/k, Sᵥ = NBA/kG, k_g = k/NBA, S = IgG/(I − Ig), and R = V/Ig − G.
Case Study 12radial magnetic field
Scenario: A moving coil galvanometer has N turns, coil area A, magnetic field B, galvanometer resistance G and torsional constant k. A current produces angular deflection θ.
Questions: find current, sensitivity, figure of merit or required shunt/series resistance.
Solution: Use NBIA = kθ, I = kθ/NBA, Sᵢ = NBA/k, Sᵥ = NBA/kG, k_g = k/NBA, S = IgG/(I − Ig), and R = V/Ig − G.
Case Study 13current sensitivity
Scenario: A moving coil galvanometer has N turns, coil area A, magnetic field B, galvanometer resistance G and torsional constant k. A current produces angular deflection θ.
Questions: find current, sensitivity, figure of merit or required shunt/series resistance.
Solution: Use NBIA = kθ, I = kθ/NBA, Sᵢ = NBA/k, Sᵥ = NBA/kG, k_g = k/NBA, S = IgG/(I − Ig), and R = V/Ig − G.
Case Study 14voltage sensitivity
Scenario: A moving coil galvanometer has N turns, coil area A, magnetic field B, galvanometer resistance G and torsional constant k. A current produces angular deflection θ.
Questions: find current, sensitivity, figure of merit or required shunt/series resistance.
Solution: Use NBIA = kθ, I = kθ/NBA, Sᵢ = NBA/k, Sᵥ = NBA/kG, k_g = k/NBA, S = IgG/(I − Ig), and R = V/Ig − G.
Case Study 15figure of merit
Scenario: A moving coil galvanometer has N turns, coil area A, magnetic field B, galvanometer resistance G and torsional constant k. A current produces angular deflection θ.
Questions: find current, sensitivity, figure of merit or required shunt/series resistance.
Solution: Use NBIA = kθ, I = kθ/NBA, Sᵢ = NBA/k, Sᵥ = NBA/kG, k_g = k/NBA, S = IgG/(I − Ig), and R = V/Ig − G.
Case Study 16ammeter conversion
Scenario: A moving coil galvanometer has N turns, coil area A, magnetic field B, galvanometer resistance G and torsional constant k. A current produces angular deflection θ.
Questions: find current, sensitivity, figure of merit or required shunt/series resistance.
Solution: Use NBIA = kθ, I = kθ/NBA, Sᵢ = NBA/k, Sᵥ = NBA/kG, k_g = k/NBA, S = IgG/(I − Ig), and R = V/Ig − G.
Case Study 17voltmeter conversion
Scenario: A moving coil galvanometer has N turns, coil area A, magnetic field B, galvanometer resistance G and torsional constant k. A current produces angular deflection θ.
Questions: find current, sensitivity, figure of merit or required shunt/series resistance.
Solution: Use NBIA = kθ, I = kθ/NBA, Sᵢ = NBA/k, Sᵥ = NBA/kG, k_g = k/NBA, S = IgG/(I − Ig), and R = V/Ig − G.
Case Study 18torque balance
Scenario: A moving coil galvanometer has N turns, coil area A, magnetic field B, galvanometer resistance G and torsional constant k. A current produces angular deflection θ.
Questions: find current, sensitivity, figure of merit or required shunt/series resistance.
Solution: Use NBIA = kθ, I = kθ/NBA, Sᵢ = NBA/k, Sᵥ = NBA/kG, k_g = k/NBA, S = IgG/(I − Ig), and R = V/Ig − G.
Case Study 19instrument damage
Scenario: A moving coil galvanometer has N turns, coil area A, magnetic field B, galvanometer resistance G and torsional constant k. A current produces angular deflection θ.
Questions: find current, sensitivity, figure of merit or required shunt/series resistance.
Solution: Use NBIA = kθ, I = kθ/NBA, Sᵢ = NBA/k, Sᵥ = NBA/kG, k_g = k/NBA, S = IgG/(I − Ig), and R = V/Ig − G.
Case Study 20experimental current measurement
Scenario: A moving coil galvanometer has N turns, coil area A, magnetic field B, galvanometer resistance G and torsional constant k. A current produces angular deflection θ.
Questions: find current, sensitivity, figure of merit or required shunt/series resistance.
Solution: Use NBIA = kθ, I = kθ/NBA, Sᵢ = NBA/k, Sᵥ = NBA/kG, k_g = k/NBA, S = IgG/(I − Ig), and R = V/Ig − G.

17. Graphs and Flowcharts

Graphs and concept flowcharts
Linear scale and sensitivity flowcharts θI θ = (NBA/k) I, straight line through origin Current sensitivity Sᵢ Sᵢ = θ/I = NBA/k Increase N, B, A; decrease k Sᵥ = θ/V = NBA/kG
Reference: NCERT Class 12 Physics, Moving Charges and Magnetism. Diagram redrawn as an original educational SVG for classroom notes.

The θ-I graph is a straight line through the origin because θ = (NBA/k)I. The flowcharts summarize current sensitivity, voltage sensitivity and conversion logic.

18. Final Revision Sheet

Deflecting torqueτ_m = NBIA
Restoring torqueτ_r = kθ
EquilibriumNBIA = kθ
CurrentI = kθ/NBA
Current sensitivitySᵢ = NBA/k
Voltage sensitivitySᵥ = NBA/kG
Figure of meritk_g = k/NBA
Ammeter shuntS = IgG/(I - Ig)
Voltmeter resistanceR = V/Ig - G

CBSE derivation: NBIA = kθ. NEET trap: radial field makes sinα = 1. JEE trap: increasing N may increase G, so voltage sensitivity may not increase.

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