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JEE • PHYSICS • UNITS & MEASUREMENTS

Units & measurements practice · Mixed difficulty

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These sets use single-correct-answer MCQs. They do not cover every JEE Main or JEE Advanced question format and are not full-length mock papers.

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Showing 391-420 of 616 questions

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391 Easy
391 of 616
Understanding +4 | -1
The dimensions of (μ0ε0)−1/2\left(\mu_0 \varepsilon_0\right)^{-1 / 2} are
View answer and explanation
Correct option: B
[LT−1]\left[\mathrm{LT}^{-1}\right]
Option B ([LT−1\mathrm{LT}^{-1}]) is correct because (μ0ε0)−1/2(\mu_0 \varepsilon_0)^{-1 / 2} represents the speed of light, which has dimensions of length per time.
392 Medium
392 of 616
Understanding +4 | -1
The maximum static friction on a body is F=μNF = \mathrm{\mu }N. Here, N= normal reaction force on the body μ=\mathrm{\mu } = coefficient of static friction. The dimensions of μ are
View answer and explanation
Correct option: C
Dimensionless
The correct answer is C (Dimensionless) because the coefficient of friction is a ratio of two forces, making it dimensionless.
393 Medium
393 of 616
Analyzing +4 | -1
The physical quantities not having same dimensions are
View answer and explanation
Correct option: B
Momentum and Planck’s constant
Option B (Momentum and Planck’s constant) is correct because momentum has dimensions of [MLT⁻¹] while Planck's constant has dimensions of [ML²T⁻¹], which are different.
394 Easy
394 of 616
Understanding +4 | -1
Statement-I: The size (u) of the unit of physical quantity and its numerical magnitude (n) are related to each other by the relation nu=\mathrm{nu}= constant
Statement-II: Numerical value is inversely proportional to the size of the unit chosen.
View answer and explanation
Correct option: A
Statement-I is true and statement-II is true
Statement-I is true and statement-II is true. The relationship between the numerical value and the unit size is inversely proportional, making both statements correct.
395 Medium
395 of 616
Understanding +4 | -1
Assertion : When we change the unit of measurement of a
quantity, its numerical value changes.
Reason : Smaller the unit of measurement smaller is its
numerical value.
View answer and explanation
Correct option: C
Assertion is correct, reason is incorrect
Assertion is correct because changing units changes the numerical value. Reason is incorrect because smaller units have larger numerical values.
396 Medium
396 of 616
Understanding +4 | -1
A suitable unit for gravitational constant is
View answer and explanation
Correct option: C
N  m2  kg−2N\;{m^2}\;k{g^{ - 2}}
Option C is correct because the gravitational constant G has units of Nm2kg−2N m^2 kg^{-2}, derived from the gravitational force equation.
397 Medium
397 of 616
Application +4 | -1
A screw gauge has least count of 0.01mm\mathrm{0}\mathrm{.01 mm} and there are 50\mathrm{50} divisions in its circular scale. The pitch of the screw gauge is :
View answer and explanation
Correct option: C
0.5  mm\mathrm{0}\mathrm{.5}\,\,\mathrm{mm}
Option C (0.5 mm) is correct because the pitch is calculated by multiplying the least count by the number of divisions on the circular scale.
398 Medium
398 of 616
Application +4 | -1
Wavelength of ray of light is 0.00006 m. It is equal to
View answer and explanation
Correct option: B
60 micron
Option B (60 micron) is correct because 0.00006 m is equal to 60 micrometers.
399 Easy
399 of 616
Understanding +4 | -1
Statement-I: Two quantities which are to be added must have the same dimensions
Statement-II: Two quantities which are to be multiplied may have the same dimensions.
View answer and explanation
Correct option: A
Statement-I is true and statement-II is true
Statement-I is true because quantities can only be added if they have the same dimensions, and Statement-II is true because quantities can be multiplied regardless of their dimensions.
400 Hard
400 of 616
Analyzing +4 | -1
Given a charge q,q, current II and permeability of vacuum μ0.\mu_0. Which of the following quantity has the dimension of momentum?
View answer and explanation
Correct option: B
qμ0Iq \mu_0 I
Option B (qμ0Iq \mu_0 I) is correct because the dimensional analysis confirms that the product of charge, permeability of vacuum, and current has the dimensions of momentum.
401 Medium
401 of 616
Analyzing +4 | -1
Assertion : Rate of flow of a liquid represents velocity of flow.

Reason : The dimensions of rate of flow are [MLT][M L T].
View answer and explanation
Correct option: D
If the assertion and reason both are false.
Option D (If the assertion and reason both are false) is correct because rate of flow is volume per unit time, not velocity, and its dimensions are [L³T⁻¹], not [MLT].
402 Easy
402 of 616
Understanding +4 | -1
Given below are two statements: one is labelled as Assertion (A) and the other is labelled as Reason (R).

Assertion (A) : In Vernier calliper if positive zero error exists, then while taking measurements, the reading taken will be more than the actual reading.

Reason (R) : The zero error in Vernier Calliper might have happened due to manufacturing defect or due to rough handling.
In the light of the above statements, choose the
correct answer from the options given below:
View answer and explanation
Correct option: C
Both (A) and (R) are correct and (R) is the
correct explanation of (A)
Option C is correct because a positive zero error in a Vernier calliper leads to readings greater than the actual value, and this error can arise from manufacturing defects or rough handling.
403 Medium
403 of 616
Analyzing +4 | -1
A thin 1 m1 \mathrm{~m} long rod has a radius of 5 mm5 \mathrm{~mm}. A force of 50π kN50 \pi \, \mathrm{kN} is applied at one end to determine its Young's modulus. Assume that the force is exactly known. If the least count in the measurement of all lengths is 0.01 mm0.01 \mathrm{~mm}, which of the following statements is false?
View answer and explanation
Correct option: A
The maximum value of YY that can be determined is 1014 N/m210^{14} \mathrm{~N} / \mathrm{m}^2
Option A (The maximum value of YY that can be determined is 1014 N/m210^{14} \mathrm{~N} / \mathrm{m}^2) is false because the calculated Young's modulus is significantly lower than this value, given the provided parameters and uncertainties.
404 Medium
404 of 616
Remembering +4 | -1
Which of the following is the smallest unit
View answer and explanation
Correct option: C
Fermi
Option C (Fermi) is correct because 1 Fermi is equal to 10-15 meters, which is the smallest unit among the given options.
405 Medium
405 of 616
Understanding +4 | -1
1kWh  =1kWh\; =
View answer and explanation
Correct option: B
36×105J36 \times {10^5}J
Option B (36×105J36 \times {10^5}J) is correct because 1 kWh is equal to 1000 watts multiplied by 3600 seconds, which results in 36×10536 \times {10^5} Joules.
406 Medium
406 of 616
Understanding +4 | -1
Velocity of sound in a gas is given by v=γpρv=\sqrt{\frac{\gamma p}{\rho}}. Dimensional formula for γ\gamma is
View answer and explanation
Correct option: B
[M0 L0 T0]\left[\mathrm{M}^0 \mathrm{~L}^0 \mathrm{~T}^0\right]
Option B ([M⁰ L⁰ T⁰]) is correct because γ is a dimensionless quantity, being the ratio of two specific heats.
407 Medium
407 of 616
Application +4 | -1
A public park, in the form of a square, has an area of (100±0.2)m2\left( {100 \pm 0.2} \right){\mathrm{m}^2} . The side of park is
View answer and explanation
Correct option: A
(10±0.01)m\left( {10 \pm 0.01} \right)m
Option A ((10±0.01)m\left( {10 \pm 0.01} \right)m) is correct because it accurately calculates the side length and its associated uncertainty using error propagation.
408 Easy
408 of 616
Remembering +4 | -1
The value of Planck's constant in SI unit is
View answer and explanation
Correct option: D
6.63×10−34 J−s6.63 \times 10^{-34} \mathrm{~J}-\mathrm{s}
Option D (6.63×10−34 J−s6.63 \times 10^{-34} \mathrm{~J}-\mathrm{s}) is correct because it represents the value of Planck's constant in SI units.
409 Easy
409 of 616
Understanding +4 | -1
Statement-1: Two or more than two physical quantities may have same dimension.

Statement-2: A physical quantity may have several units.
View answer and explanation
Correct option: B
Statement-1 is true, statement-2 is true and statement- 2 is NOT the correct explanation for statement-1
Option B (Statement-1 is true, statement-2 is true and statement- 2 is NOT the correct explanation for statement-1) is correct because both statements are true, but the fact that a quantity can have multiple units doesn't explain why different quantities can have the same dimensions.
410 Medium
410 of 616
Application +4 | -1
The velocity of water waves (v) may depend on their
wavelength l, the density of water r and the acceleration
due to gravity, g. The method of dimensions gives the
relation between these quantities is
View answer and explanation
Correct option: B
V2∝gλ{V^2} \propto g\lambda
Option B (V2∝gλ{V^2} \propto g\lambda) is correct because dimensional analysis shows that the velocity of water waves is proportional to the square root of the product of gravity and wavelength.
411 Easy
411 of 616
Analyzing +4 | -1
Statement-I: Surface tension and spring constant have the same dimensions.
Statement-II: Both are equivalent to force per unit length
View answer and explanation
Correct option: A
Statement-I is true and statement-II is true
Option A is correct because both statements are true: surface tension and spring constant have the same dimensions, and both are equivalent to force per unit length.
412 Easy
412 of 616
Analyzing +4 | -1
The dimensional formula for (Capacitance)(Electrostatic Potential)2(Permitivity)(Electric field)2\frac{(\text {Capacitance})(\text {Electrostatic Potential})^2}{(\text {Permitivity})(\text {Electric field})^2} is same as that of:
View answer and explanation
Correct option: C
 Mass  Density \frac{\text { Mass }}{\text { Density }}
Option C is correct because the given expression simplifies to volume, which has the same dimensions as mass/density.
413 Medium
413 of 616
Analyzing +4 | -1
The units of length, velocity and force are doubled. Which of the following is the correct change in the other units?
View answer and explanation
Correct option: C
Unit of momentum is doubled
Option C (Unit of momentum is doubled) is correct because momentum is mass times velocity, and only velocity is doubled while mass remains unchanged.
414 Medium
414 of 616
Analyzing +4 | -1
Out of the following which pair of quantities do not have same dimensions
View answer and explanation
Correct option: D
Torque and moment of inertia
Option D (Torque and moment of inertia) is correct because torque has dimensions of [ML2T−2][ML^2T^{-2}] while moment of inertia has dimensions of [ML2][ML^2].
415 Medium
415 of 616
Understanding +4 | -1
Assertion: The measure of a physical quantity is independent of the system of units.

Reason: The smaller is unit, bigger is the measure of the physical quantity and vice-versa.
View answer and explanation
Correct option: A
If both assertion and reason are true and reason is the correct explanation of the assertion.
Option A (If both assertion and reason are true and reason is the correct explanation of the assertion) is correct because the measure of a physical quantity is indeed independent of the system of units, and the reason correctly explains why.
416 Medium
416 of 616
Understanding +4 | -1
Linear momentum and angular momentum have the same dimensions in
View answer and explanation
Correct option: C
Mass and time
Option D (Mass, length and time) is correct because linear momentum has dimensions of [MLT⁻¹] and angular momentum has dimensions of [ML²T⁻¹], so they share dimensions in mass, length, and time.
417 Easy
417 of 616
Application +4 | -1
Error in measurement of radius of sphere is 4% then maximum % error in volume is
View answer and explanation
Correct option: D
0.12
Option D (12%) is correct because the percentage error in volume is three times the percentage error in the radius.
418 Medium
418 of 616
Analyzing +4 | -1
The thrust developed by a rocket-motor is given by F=mv+A(p1−p2)F = mv + A\left( {{p_1} - {p_2}} \right), where m is the mass of the gas ejected per unit time, vv is velocity of the gas, A is area of cross-section of the nozzle, p1.p2{p_1}.{p_2} are the pressures of the exhaust gas and surrounding atmosphere. The formula is dimensionally
View answer and explanation
Correct option: A
Correct
Option A (Correct) is correct because each term in the equation has the dimensions of force (MLT-2), making the equation dimensionally consistent.
419 Medium
419 of 616
Application +4 | -1
A bee of mass 0.000087 kg0.000087 \mathrm{~kg} sits on a flower of mass 0.0123 kg0.0123 \mathrm{~kg}. What is the total mass supported by the stem of the flower up to appropriate significant figures?
View answer and explanation
Correct option: D
0.012 kg0.012 \mathrm{~kg}
Option D (0.012 kg0.012 \mathrm{~kg}) is correct because the sum of the masses must be rounded to the least number of significant figures, which is three in this case, based on the flower's mass.
420 Medium
420 of 616
Remembering +4 | -1
Coefficient of thermal conductivity has the dimensions
View answer and explanation
Correct option: A
[MLT−3K−1]\left[ {\mathrm{ML}{\mathrm{T}^{ - 3}}{\mathrm{K}^{ - 1}}} \right]
Option A ([MLT−3K−1]\left[ {\mathrm{ML}{\mathrm{T}^{ - 3}}{\mathrm{K}^{ - 1}}} \right]) is correct because it represents the correct dimensions for the coefficient of thermal conductivity.
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