Question 1
Easy Questions for NEETShow Answer
Correct Answer: (3)
Solution:
There are seven base quantities, (i) Mass (ii) Length (iii) Time (iv) Current (v) Amount of substance (vi) Luminous intensity (vii) Temperature
Practice Units and Measurements questions first, followed by Physical World questions, with answers hidden for self-testing.
Best of Best Questions to Crack NEET Physics
Quickly revise important Units and Measurements facts before attempting the MCQs.
[L^2]
SI Unit: m^2
[L^3]
SI Unit: m^3
[M L^-3]
SI Unit: kg m^-3
[L T^-1]
SI Unit: m s^-1
[L T^-2]
SI Unit: m s^-2
[M L T^-1]
SI Unit: kg m s^-1
[M L T^-2]
SI Unit: N
[M L^2 T^-2]
SI Unit: J
[M L^2 T^-2]
SI Unit: J
[M L^2 T^-3]
SI Unit: W
[M L^-1 T^-2]
SI Unit: Pa or N m^-2
[M L^2 T^-2]
SI Unit: N m
[M^-1 L^3 T^-2]
SI Unit: N m^2 kg^-2
[M L T^-1]
SI Unit: N s
[M L^-1 T^-2]
SI Unit: N m^-2
[M^0 L^0 T^0]
SI Unit: No unit
[M L^-1 T^-2]
SI Unit: N m^-2
[M T^-2]
SI Unit: N m^-1
[M T^-2]
SI Unit: J m^-2
[M L^-1 T^-1]
SI Unit: N m^-2 s or Pa s
[M^0 L^0 T^0]
SI Unit: rad
[T^-1]
SI Unit: rad s^-1
[T^-2]
SI Unit: rad s^-2
[M L^2]
SI Unit: kg m^2
[L]
SI Unit: m
[M L^2 T^-1]
SI Unit: kg m^2 s^-1
[T]
SI Unit: s
[T^-1]
SI Unit: s^-1 or Hz
[M L^2 T^-1]
SI Unit: J s
[M^0 L^0 T^0]
SI Unit: No unit
[T^-1]
SI Unit: s^-1
[M L^-2 T^-2]
SI Unit: Pa m^-1
[M T^-2]
SI Unit: N m^-1
[M L^2 T^-2]
SI Unit: J
[L^2 T^-2 K^-1]
SI Unit: J kg^-1 K^-1
[L^2 T^-2]
SI Unit: J kg^-1
[M L T^-3 K^-1]
SI Unit: J s^-1 m^-1 K^-1
[M L^2 T^-2 K^-1]
SI Unit: J K^-1
[M L^2 T^-2 K^-1 mol^-1]
SI Unit: J mol^-1 K^-1
[M L^2 T^-2 K^-1]
SI Unit: J K^-1
[M T^-3 K^-4]
SI Unit: J s^-1 m^-2 K^-4
[M T^-3]
SI Unit: J s^-1 m^-2
[A T]
SI Unit: C
[M L^2 T^-3 A^-1]
SI Unit: V
[M L^2 T^-3 A^-2]
SI Unit: Ω
[M^-1 L^-2 T^4 A^2]
SI Unit: F
[M L^2 T^-2 A^-2]
SI Unit: H
[M^-1 L^-3 T^4 A^2]
SI Unit: A^2 s^4 N^-1 m^-2
[M^0 L^0 T^0]
SI Unit: No unit
[M L T^-3 A^-1]
SI Unit: N C^-1 or V m^-1
[M^-1 L^-2 T^3 A^2]
SI Unit: Ω^-1 or mho
[M L^3 T^-3 A^-2]
SI Unit: Ω m
[M^-1 L^-3 T^3 A^2]
SI Unit: Ω^-1 m^-1
[L A T]
SI Unit: C m
[M T^-2 A^-1]
SI Unit: T
[M L^2 T^-2 A^-1]
SI Unit: Wb
[M L T^-2 A^-2]
SI Unit: Wb A^-1 m^-1
[L^2 A]
SI Unit: A m^2
[L A]
SI Unit: A m
https://physicstutor.kumarphysicsclasses.com/physics-notes-units-and-measurements/
Correct Answer: (3)
Solution:
There are seven base quantities, (i) Mass (ii) Length (iii) Time (iv) Current (v) Amount of substance (vi) Luminous intensity (vii) Temperature
Correct Answer: (4)
Solution:
Light year is the unit of distance 1 light year = 9.46 × 1015 m
Correct Answer: (2)
Solution:
One astronomical unit is the average distance between earth and sun 1 astronomical unit (AU) = 1.496 × 1011 m
Correct Answer: (2)
Solution:
q Current I = ⇒ q = It t q = Ampere second So, ampere second is the unit of charge.
Correct Answer: (2)
Solution:
Nm → Unit of torque mN → Milli newton ⇒ 10−3 N nm → Nano metre Ns → Unit of momentum
Correct Answer: (2)
Solution:
180º = π radian π rad 1º = π × 60 rad 60º = π 60º = rad
Correct Answer: (2)
Solution:
The total plane angle is 360º or 2π rad.
Correct Answer: (3)
Solution:
1 amu = 1.66 × 10 −27 kg (Measurement of Length, Mass and Time, Accuracy, Precision)
Correct Answer: (3)
Solution:
θ = Arc length θ Radius D D d θ = D ⇒ d = Dθ d
Correct Answer: (1)
Solution:
Time span of human life = 109 s Age of universe = 1017 s So, Age of universe = 10 = 10 8 Time of human 10 9 If, Age of universe = 10 8 ⇒ Age of universe = 10 10 s
Correct Answer: (2)
Solution:
Speed of light ⇒ 3 × 108 m s−1 Order of magnitude = 8
Correct Answer: (3)
Solution:
A measurement having more number of decimal places is the one with the most precision. So, 20.01 g is most precise.
Correct Answer: (2)
Solution:
Most accurate reading is the one having minimum error. So, 16 − 6.281 = 0.28 cm 16.5 − 6.281 = 0.22 cm 15.99 − 6.281 = 0.29 cm 16.0 − 6.281 = 0.28 cm So, second reading is most accurate.
Correct Answer: (4)
Solution:
3 × 10−3 3.0 × 10−3 3.0 × 10−3 3.00 × 10−3 So, fourth measurement is most precise.
Correct Answer: (1)
Solution:
The quantity having smallest magnitude should be measured very precisely as it is likely to contribute the maximum relative error. (Errors)
Correct Answer: (1)
Solution:
ΔL 0.001 The percentage error is × 100% = × 100% = 0.1246% (cid:2) 0.125% L 0.802
Correct Answer: (4)
Solution:
V V = IR ⇒ R = I ⎛ ΔR ⎞ ⎛ ΔV ΔI ⎞ ⇒ ⎜ ⎟ × 100% = ⎜ + ⎟ × 100% ⎝ R ⎠ ⎝ V I ⎠ ΔR ⇒ × 100% = 3% + 2% = 5% R
Correct Answer: (3)
Solution:
Volume of cube, V = side3 ΔV 3 Δside = V side ΔV ΔV = 3 × 0.027 ⇒ = 0.081 V V
Correct Answer: (1)
Solution:
Zero error is a part of systematic error.
Correct Answer: (2)
Solution:
m = 20.23 g ± 0.01 g m = (5.75 ± 0.01) g m − m = [(20.23 − 5.75) ± 0.02] g 1 2 Δm = (14.48 ± 0.02) g
Correct Answer: (2)
Solution:
r = (2.6 ± 0.1) cm V = πr 3 ΔV 3Δr × 100% = × 100% V r ΔV 3 × 0.1 × 100% = × 100% V 2.6
Correct Answer: (1)
Solution:
The only method of reducing random errors is by taking more and more number of observations. (Significant figures)
Correct Answer: (2)
Solution:
The volume of cube is l3 v = (1.2 cm)3 = 1.728 × 106 cm3 v (cid:2) 1.7 × 106 cm3 Answer should be reported in minimum number of significant figures.
Correct Answer: (4)
Solution:
A pure number has infinite number of significant figures.
Correct Answer: (2)
Solution:
m = 1.6 g m = 7.32 g m = 4.238 g m + m + m = 13.158 g 1 2 3 but answer should be reported in one decimal place only. ∴ m = 13.2 g
Correct Answer: (3)
Solution:
l = 10.2 cm w = 6.8 cm Area = lw = 10.2 × 6.8 = 69.36 ⇒ Area = 69 cm2
Correct Answer: (4)
Solution:
41.68 cm The rightmost digit is most insignificant and leftmost is most significant. So, 8 → most insignificant 4 → most significant
Correct Answer: (2)
Solution:
The non-zero digits after the decimal places are significant.
Correct Answer: (2)
Solution:
The trailing zeros are not significant. So, only two digits are significant.
Correct Answer: (4)
Solution:
Zeores appearing between and after non-zero numbers are significant. 0.020040
Correct Answer: (4)
Solution:
4.700 ⇒ Four significant figures. Also, 470.0 m ⇒ Four significant figures.
Correct Answer: (3)
Solution:
2.7465 g ⇒ Last two digits are most insignificant.
Correct Answer: (1)
Solution:
m = 4.237 g V = 1.72 cm3 Mass 4.237 g = Density = Volume 1.72 cm 3 ⇒ d = 2.46 gcm −3
Correct Answer: (2)
Solution:
2.845 ⇒ 2.84
Correct Answer: (1)
Solution:
5.997 ⇒ 6.00 m (Dimensions of Physical Quantities, Formulae and Equations)
Correct Answer: (2)
Solution:
The dimensions of change in velocity is same as that of velocity [M0LT−1].
Correct Answer: (2)
Solution:
The dimensional formula is [ML2T−2]
Correct Answer: (3)
Solution:
Wavelength and focal length both are have units of length.
Correct Answer: (2)
Solution:
Refractive index is a pure number, hence dimensionless.
Correct Answer: (3)
Solution:
The dimensional formula for pressure Force MLT−2 P = = ⇒ [ML−1T−2 ] Area L2
Correct Answer: (2)
Solution:
W ML2T−2 Dimensional formula of power = = = [ML2T−3] t T Current → [A] W ML2T−2 V = = = [ML2T−3A−1] q AT E = [ML2T−2 ] E ML2T−2 So, R = = ⇒ [ML2T−3A−2] I2t A2T ML2T−3A−1 and V = IR ⇒ R = ⇒ [ML2T−3A−2] A So, (2) is the correct formula.
Correct Answer: (4)
Solution:
W = [ML2A−1T−3 ] Dimension of q which is different from dimension of force [MLT−2]
Correct Answer: (3)
Solution:
Focal length ⇒ f = [L]
Correct Answer: (3)
Solution:
Gravitational constant is a dimensional constant. [G] = [M−1L3T−2]
Correct Answer: (4)
Solution:
Energy ML2T−2 Solar constant [S] = = ⇒ [MT−3] Area × Time L2T (Application of Dimensions)
Correct Answer: (1)
Solution:
F ∝ V aρb g c F = [L3 ]a [ML−3 ]b [LT−2 ]c [MLT−2 ] = F = [MbL3a−3b+cT−2c ] On comparing, b = 1 , −2c = − 2 ⇒ c = 1 3a − 3b + c = 1 ⇒ 3a − 3 + 1 = 1 ⇒ 3a − 2 = 1 ⇒ 3a = 3 ⇒ a = 1 So, on putting all these values, F = V ρg A x
Correct Answer: (1)
Solution:
A x u = x + B By the principle of homogeneity, x = B (dimensionally) ⇒ B = [L] AL1/2 and [ML2T−2 ] = L [ML2T−2 ] =AL−1/2 A = [ML3/2T−2 ] ( )
Correct Answer: (4)
Solution:
P = P e−αt2 The power of exponent is dimensionless, αt 2 = [M0L0T0 ] α = [T−2 ]
Correct Answer: (2)
Solution:
The dimensional formula of energy E = [ML2T−2 ] So, dimensions of i) Mass → 1 ii) Length → 2 iii) Time → −2
Correct Answer: (2)
Solution:
Q = ma sb θc [ML2T−2] = [Ma][L2bT−2bK−b][Kc] ⇒ a = 1 , 2b = 2 ⇒ b = 1 − b + c = 0 ⇒ b = c ⇒ c = 1 Q = msΔT Q ⇒ s = mΔT Objective Type Questions (System of Units)
Correct Answer: (4)
Solution:
1 light year = 9.46 × 1015 m
Correct Answer: (3)
Solution:
p = F × t p′ = 2F × t p′ = 2p
Correct Answer: (1)
Solution:
Impulse MLT−1 = ⇒ [ML−1T−1] Area L2 Coefficient of viscosity ⇒ η = [ML−1T−1] Impulse = coefficient of viscosity So, Area
Correct Answer: (3)
Solution:
Work → [ML2T−2] n v = n v 1 1 2 2 (8)M L2 T−2 1 1 1 = n M L2 T−2 2 2 2 2 ⎡ M ⎤ ⎡ L ⎤ 2 ⎡ T ⎤ −2 ⇒ 8 1 1 1 = n ⎢ ⎣M ⎥ ⎦ ⎢ ⎣L ⎥ ⎦ ⎢ ⎣ T ⎥ ⎦ 2 2 2 2 ⎡ M ⎤ ⎡L ⎤ 2 ⎡ 2T ⎤ −2 ⇒ 8 1 1 1 = n ⎢ ⎣ 2M ⎥ ⎦ ⎢ ⎣L ⎥ ⎦ ⎢ ⎣ T ⎥ ⎦ 2 1 1 1 1 1 ⇒ 8 × × = n 2 4 2 ⇒ n = 1 So, unit of 8 joule = 1× new units ⎛ 2πct ⎞ ⎛ 2πx ⎞
Correct Answer: (4)
Solution:
⎛ 2πct ⎞ ⎛ 2πx ⎞ y = 2A sin⎜ ⎟cos⎜ ⎟ ⎝ λ ⎠ ⎝ λ ⎠ ct = dimensionless ⇒ ct = λ λ x = dimensionless ⇒ x = λ λ (Errors)
Correct Answer: (3)
Solution:
πR3 Volume of sphere = ΔV ΔR ⇒ × 100% = 3 × × 100% = 3 × 2% V R ΔV ⇒ × 100% = 6% V
Correct Answer: (1)
Solution:
Random errors can be reduced by taking a large number of observations.
Correct Answer: (4)
Solution:
Force Pressure = Area ΔP ΔF 2ΔL × 100% × 100% + × 100% = = 4% + 2 × 2% P F L ΔP × 100% = 8% P
Correct Answer: (2)
Solution:
r = (5.3 ± 0.1) cm V = πr 3 ΔV 3Δr × 100% = × 100% V r ΔV 3 × 0.1 × 100% = × 100 V 5.3
Correct Answer: (4)
Solution:
Momentum p2 KE = = Mass 2m ΔK ⎛ 2Δp ⎞ ⎛ Δm ⎞ K × 100% = ⎜ ⎝ p × 100 ⎟ ⎠ % + ⎜ ⎝ m × 100⎟ ⎠ % = 2 × 2% + 3% ΔK × 100% ⇒ 7% K
Correct Answer: (4)
Solution:
L T = 2π g ⇒ T 2 = 4π2 L g Δg ΔL 2ΔT × 100% = × 100% + × 100% g L T Δg × 100% = (α + 2β) × 100 g
Correct Answer: (1)
Solution:
A = (100 ± 0.2) m2 100 = l 2 ⇒ l = 10 m ΔA 2Δl = A l 0.2 Δl = 2 × 100 10 ⇒ Δl = 0.01 m So, length = (10 ± 0.01) m
Correct Answer: (2)
Solution:
X = [MaLbT−c] ΔX aΔM bΔL cΔT × 100% = × 100% + × 100% + × 100% X M L T ΔX ⇒ × 100% = (aα + bβ + cγ )% X
Correct Answer: (2)
Solution:
Least count = ΔT = s = 0.2 s T = 25 s ΔT 0.2 × 100% × 100% Percentage error = = = 0.8% T 25
Correct Answer: (2)
Solution:
g = LT−2 Δg ΔL 2ΔT Δg = = ⇒ = e 1 + 2e 2 g L T g (Dimensions of Physical Quantities, Formulae and Equations)
Correct Answer: (1)
Solution:
On checking the dimensionality the correct relation is πPr 4 V = 8ηl
Correct Answer: (1)
Solution:
EJ2 ML2T−2 ⋅ (ML2T−1)2 ML2T−2M2L4T−2 ⇒ m5G2 M5 ⋅ (M−1L3T−2 )2 = M5M−2L6T−4 ⇒ [M0L0T0] = Angle (Dimensionless) d 2y
Correct Answer: (3)
Solution:
d 2y y will have dimensions of dx2 x2 y → pressure, x → velocity gradient V LT−1 x → ⇒ ⇒ T−1 L L y ML−1T−2 = ⇒ [ML−1] x2 T−2 (Application of Dimensions) α α − t 2
Correct Answer: (3)
Solution:
α − t 2 F = βv 2 Dimensionally, α = [T2] [T2 ] [MLT−2] = β[L2T−2 ] T2 β = [MLT−2 ⋅ L2T−2 ] ⇒ β = [M−1L−3T6] α T2 Dimensions of = = [ML3T−4] β M−1L−3T6
Correct Answer: (3)
Solution:
This statement is completely correct. If a quantity depends upon two other quantities which are dimensionally same then formula's validity can be checked but it can't be derived by the method of dimensions.
Correct Answer: (2)
Solution:
G = [Ea db Pc] E = [ML2T−2] d = [ML−3] P = [ML2T−3] G = [M−1L3T−2] [M−1L3T−2] = [ML2T−2]a [ML−3]b [ML2T−3]c a + b + c = −1 2a − 3b + 2c = 3 −2a − 3c = −2 ⇒ 2a + 3c = 2 On solving, a = −2 b = −1 c = 2 So, G = [E −2d −1P2 βγ
Correct Answer: (1)
Solution:
⎛ βγ ⎞ y = x2 cos2 2π ⎜ ⎟ ⎝ α ⎠ The argument of a trigonometric ratio is always dimensionless. βγ T−1 = [M0L0T0 ] or βγ = α ⇒ γ = ⇒ [LT−2] α L−1T and y = x2 ⇒ [L2] α = s−1 ⇒ [T−1], β = [LT−1]−1 ⇒ [L−1T] y = m2 γ = m s−2
Correct Answer: (3)
Solution:
P xI yc z P → Pressure → [ML−1T−2] E ML2T−2 I → Intensity → ⇒ ⇒ [MT−3] AT L2T c → Speed of light = [LT−1] [M0L0T0] = [ML−1T−2]x [MT−3]y [LT−1]z x = −y ⇒ x + y = 0, − x + z = 0 ⇒ x = z x = z = −y
Correct Answer: (3)
Solution:
(N − N ) N = −D 2 1 (Z − Z ) 2 1 Dimensionally, N(Z − Z ) D = 2 1 (N − N ) 2 1 Given, N , N → Number of particles per unit volume. 2 1 N N , N → ⇒ [L−3 ] 2 1 V Z − Z → [L] 2 1 Number of particles N → Area ⋅ (T) N → [L−2T−1] L−2T−1 × L So, D = ⇒ [L2T−1] L−3
Correct Answer: (4)
Solution:
f → Frequency → [T−1] m → Mass → [M] c → Constant f MLT −2 K = = ⇒ [MT−2] x L [M0L0T−1] = c[Mx My T−2y] x + y = 0, −2y = − 1 −1 1 ⇒ x = ⇒ y = 2 2
Correct Answer: (1)
Solution:
Force MLT−2 Surface tension = = ⇒ [MT−2] Length L Surface tension = [MT−2] E → [ML2T−2] V → [LT−1] T → [T] Surface tension = [Ea Vb Tc] [MT−2] = [ML2T−2]a [LT−1]b [T]c On comparing, a = 1 , 2a + b = 0 ⇒ 2 + b = 0 ⇒ b = −2 −2a − b + c = −2 ⇒ −2 + 2 + c = −2 ⇒ c = −2 Surface tension = [EV−2T−2]
Correct Answer: (4)
Solution:
Stress Young's modulus = = [ML−1T−2] Strain F → [MLT−2] A → [L2] D → [ML−3] [ML−1T−2] = [MLT−2]a [L2]b [ML−3]c a + c = 1, a + 2b − 3c = −1 ⇒ a = 1− c ⇒ −2 = −2a − 3c ⇒ 2 = 2a + 3c ⇒ 2 = 2 − 2c + 3c ⇒ 0 = +c ⇒ c = 0 ∴ a = 1 1 + 2b = − 1 2b = −2 ⇒ b = −1 Young's modulus = [FA−1D0] Previous Years Questions e2

Correct Answer: (1)
Solution:
e2 Let = A = ML3T−2 4πε l = CxGy(A)z L = [LT−1]x [M−1L3T−2]y [ML3T−2]z −y + z = 0 ⇒ y = z ...(i) x + 3y + 3z = 1 ...(ii) −x − 4z = 0 ...(iii) From (i), (ii) & (iii) , z = y = x = −2

Correct Answer: (1)
Solution:
L ∝ hacbGc [L]1 = [M1L2T−1]a [LT−1]b [M−1L3T−2]c 1 1 3 a = , c = , b = − Solving, 2 2 2 hG ⇒ L = c3/2
Correct Answer: (2)
Solution:
Rη Equation of critical velocity, v = c ρD v ∝ η1ρ−1D−1 c ∴ x = 1, y = − 1, z = − 1
Correct Answer: (4)
Correct Answer: (4)
Solution:
M = F x V y T z M = (MLT−2)x (LT−1)y (T)z M = M x Lx+y T−2x−y+z Equating powers of M, L and T both sides x = 1, x + y = 0, −2x −y + z = 0 Solving equations x = 1, y = −1, z = 1 M = F V−1 T
Correct Answer: (4)
Solution:
a3b2 P = cd ΔP ⎛ 3Δa 2Δb Δc Δd ⎞ P × 100% = ⎜ ⎝ a + b + c + d ⎟ ⎠ × 100% = 14%
Correct Answer: (1)
Solution:
F kgms −2 F ∝ v ⇒ F = bv ⇒ b = = = kgs−1 v −1 ms
Correct Answer: (4)
Solution:
Speed of light c = ⇒ c = (με )−1/2 με 0 0 0 0 So, dimensional formula of (με )−1/2 0 0
Correct Answer: (4)
Solution:
4 g 100 g Density, n 1 u 1 = n 2 u 2 ⇒ cm 3 = n 2 × 10 3 cm 3 ⇒ n 2 = 40
Correct Answer: (2)
Correct Answer: (2)
Solution:
E 1 ML2T−2 1 Energy density = V = 2 ε 0 E2 ⇒ L3 ⇒ [ML−1T−2 ] = 2 ε 0 E2
Correct Answer: (4)
Solution:
Pressure = [ML−1T−2]
Correct Answer: (4)
Solution:
Refractive index and dielectric constant are dimensional constant ML2T−2 = [ML−1T−2 ] Energy density = L3 MLT−2 = [ML−1T−2 ] Young's modulus = L2 So, (d) & (a)
Correct Answer: (3)
Solution:
πR3 Volume of sphere = ΔV ΔR ⇒ × 100% = 3 × × 100% V R = 3 × 2% ΔV ⇒ × 100% = 6% V
Correct Answer: (1)
Solution:
V W ML2T−2 V = IR ⇒ R = = = ⇒ R = [ML2T−3A−2 ] I qI AT ⋅ A b
Correct Answer: (1)
Solution:
b v = at + t + c By the principle of homogeneity, c = t = [T] at = v ⇒ a = [LT−2] b = LT−1 ⇒ b = [L] T
Correct Answer: (1)
Solution:
h ML2T−1 = ⇒ [T−1] → Frequency I ML2
Correct Answer: (4)
Solution:
Work = Force × Displacement W = [ML2T−2 Torque = Perpendicular distance × Force = [ML2T−2]
Correct Answer: (4)
Solution:
μ 1 ε = LT−1 ⇒ μ 1 ε = L2T−2 ⇒ μ 0 = L2T 1 −2ε ⇒ μ 0 = L2T 1 −2 [ML3T−4A−2 ] ⇒ μ 0 = [MLT−2A−2 0 0 0 0 0
Correct Answer: (3, 4)
Solution:
F MLT−2 Surface tension = = = [MT−2] L L
Correct Answer: (2)
Solution:
Force MLT−2 Pressure = = ⇒ [ML−1T−2] Area L2 P = [ML−1T−2
Correct Answer: (1)
Solution:
1 ΔK ΔM 2ΔV ΔK KE = MV 2 ⇒ × 100% = × 100% + × 100% = 2% + 2 × 3% ⇒ × 100% = 8% 2 K M V K
Correct Answer: (2)
Solution:
Dimensional constant [G] = [M−1L3T−2]
Correct Answer: (3)
Solution:
RC = Time
Correct Answer: (2)
Solution:
Impulse = Δp ⇒ [MLT−1]
Correct Answer: (4)
Solution:
Mass Density = Volume Δd Δm 3Δl × 100% × 100% + × 100% = = 3% + 3 × 2% d m l Δd × 100% = 9% d ⎛ a ⎞ θ
Correct Answer: (3)
Solution:
⎛ a ⎞ θ ⎜P + ⎟ = b ⎝ V 2 ⎠ V a Dimensionally, P = V 2 ML−1T−2 × L6 = a ⇒ a = [ML5T−2 ]
Correct Answer: (1)
Solution:
L = Time R
Correct Answer: (3)
Solution:
F φ = BA = × A [F = qvB] qv MLT−2 × L2 = AT ⋅ LT−2 = [ML2T−2A−1]
Correct Answer: (2)
Solution:
Force = [MLT−2] Impulse = Force × Time ⇒ [MLT−1]
Correct Answer: (3)
Solution:
E = hν ML2T−2 = h T−1 ⇒ h = [ML2T−1] Angular momentum = mvr = MLT−1L L = [ML2T−1]
Correct Answer: (1)
Solution:
Gravitational constant = [M−1L3T−2] Assertion-Reason Type Questions
Correct Answer: (4)
Solution:
Shake → Unit of time Light year → Unit of length
Correct Answer: (3)
Solution:
Displacement Displacement gradient = ⇒ Dimensionless Length But displacement is not dimensionless.
Correct Answer: (4)
Solution:
Absolute error is always positive as it is true value − measured value
Correct Answer: (2)
Solution:
If a quantity doesnot have units so definitely it will be dimensionless but reverse is not true. Pure number → also dimensionless.
Correct Answer: (4)
Solution:
Absolute error is not dimensionless rather it will having dimensions of the measured quantity.
Correct Answer: (2)
Solution:
Higher accuracy means higher precisions. So, error will be very smaller. Low least count means low error and hence high accuracy.
Correct Answer: (3)
Solution:
The assertion is true as least count is the maximum possible error in the measurement. But the error can be greater than least count it will depend upon power of quantity.
Correct Answer: (1)
Solution:
The precisions is decided by the more number of decimal places so, 20.0004 is more precise.
Correct Answer: (1)
Solution:
Out of 20.00 and 20.000 The second measurement is more precise and more accurate also. The percentage error in second reading is less. 0.01 1 × 100 ⇒ = 0.05% 20.00 20 0.001 × 100 ⇒ 0.0005% 20.000
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Solution:
Numerical value × Unit = constant
Correct Answer: (3)
Solution:
If an equation is physically correct it has to be dimensionally correct also. But the reverse is not true.
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Those equations carrying multiplication and divisions of physical quantities can be derived but not valid for addition or subtraction.
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Assertion and reason is correct and correctly explains assertion.
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An exact number contains infinite number of significant figures.
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Solution:
Dimensionless quantity may have unit. for example, angle. Also two quantities having same dimensions may have different units. Work → ML2T−2 → Joule Torque → ML2T−2 → Nm
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(Fundamental Forces in Nature)
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(Discoveries and Nature of Physical Laws)
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Objective Type Questions (Fundamental Forces in Nature, Nature of Physical Laws)
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Weak interaction takes place through the exchange of BOSONS → W and Z bosons
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Maxwell unified electromagnetism with optics.
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Electrostatic force between proton-proton is a fundamental force.
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Leptons does not experience strong nuclear force. Assertion - Reason Type Questions
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