NEET Units and Measurements PYQs & Practice Questions

10 free NEET Physics questions on Units and Measurements, starting with previous year questions (2016–2026). Tap “Show answer” to check each one. No login needed.

Topics: Dimensional Analysis · Vernier Callipers / Zero Error · Dimensions and Dimensional Analysis · Error Analysis / Percentage Error · Fundamental Forces · SI Units · Significant Figures · Errors in Measurement · Scope of Physics · Units and Measurement · Error Analysis · Measurement and Precision

Q1NEET 2026Vernier Calliper - Zero Error
One main scale division of a Vernier calliper is equal to 1 mm and the number of divisions on the Vernier scale is 10. When both the jaws touch each other, the Vernier scale shifts to the left of zero of the main scale in such a way that the 4th Vernier division coincides with a division of the main scale. If this Vernier calliper measures the length of a wire to be 1 cm, the actual length of the wire is:
- A. 0.96 cm
- B. 1.00 cm
- C. 1.04 cm
- D. 0.60 cm
Show answer
Answer: B — 1.00 cm
Least count = 1 MSD - 1 VSD = 1mm - 0.9mm = 0.1mm = 0.01cm. Since the vernier zero is shifted to the left of the main scale zero with the 4th division coinciding, this is a negative zero error of magnitude 4 x 0.01cm = 0.04cm. Actual length = Observed reading - (Zero error) = 1cm - (-0.04cm) = 1.04cm. Note: this question was officially marked as Bonus (full credit given to all candidates) likely due to ambiguity in the zero-error sign convention used.
Q2NEET 2026Dimensional Analysis of Physical Constants
Consider that sigma_s, k_B, b represent Stefan-Boltzmann constant, Boltzmann constant and Wien's displacement law constant, respectively. The dimension of sigma_s * k_B^-1 * b is:
- A. [L^-1 K^-2]
- B. [L^-1 T^-1 K^-3]
- C. [L^-1 T^-1 K^-4]
- D. [L^-1 T^-1 K^-2]
Show answer
Answer: C — [L^-1 T^-1 K^-4]
Stefan-Boltzmann constant sigma_s has dimension [M T^-3 K^-4]. Boltzmann constant k_B has dimension [M L^2 T^-2 K^-1]. Wien's constant b has dimension [L K]. So sigma_s/k_B = [M T^-3 K^-4]/[M L^2 T^-2 K^-1] = [L^-2 T^-1 K^-3]. Multiplying by b = [L K] gives [L^-1 T^-1 K^-2].
Q3NEET 2026Index Correction in Experimental Measurements
Which of the following measurements require 'index correction'?
- A. Measurement of gravitational acceleration using simple pendulum
- B. Measurement of focal length of lenses using optical bench
- C. Measurement of speed of sound using resonance tube
- D. Measurement of resistance of a wire using meter bridge
Show answer
Answer: A — Measurement of gravitational acceleration using simple pendulum
Index correction (also called the index error or bench error correction) is applied in optical bench experiments for determining the focal length of lenses/mirrors, because the index needles (pointers) used to locate positions on the bench do not exactly coincide with the optical centre of the lens, introducing a systematic offset that must be corrected for.
Q4NEET 2026Light speed in a new unit
The speed of light in vacuum is taken as unity. If light takes 6 min 40 s to reach the Earth from the Sun, the distance between the Sun and the Earth in this new unit is:
- A. 3×10⁸
- B. 500
- C. 3×10¹⁰
- D. 400
Show answer
Answer: C — 3×10¹⁰
Time=6×60+40=400 s. Distance=speed×time=1×400=400 (in the new unit where c=1).

Practise all 71 Units and Measurements questions with a timer

Timed chapter test
Score + weak topics
Full NEET mocks & rank

Start free for 30 days

No payment, no card. Register in 2 minutes.

Q5NEET 2026Vernier calliper least count
In a vernier calliper, 20 VSD coincide with 16 MSD (each division of length 1 mm). The least count of the vernier calliper is:
- A. 0.2 cm
- B. 0.1 cm
- C. 0.02 cm
- D. 0.01 cm
Show answer
Answer: B — 0.1 cm
1 VSD=16/20 MSD=0.8mm. Least count=1MSD-1VSD=1-0.8=0.2mm=0.02 cm.
Q6NEET 2026Significant figures in density
Each side of a metallic cube of mass 5.580 kg is measured to be 9.0 cm. Keeping the significant figures in view, the density of the material of the cube can be best expressed as X×10³ kg m⁻³, where the value of X is:
- A. 7.654
- B. 7.7
- C. 7.65
- D. 7.6
Show answer
Answer: C — 7.65
Density=mass/volume=5.580/(9.0)³ cm³ → sides have 2 sig figs, so result rounds to 2 sig figs: X≈7.6.
Q7NEET 2025Dimensional Analysis
A balloon is made of a material of surface tension S and its inflation outlet (from where gas is filled in it) has small area A. It is filled with a gas of density ρ and takes a spherical shape of radius R. When the gas is allowed to flow freely out of it, its radius r changes from R to 0(zero) in time T. If the speed v(r) of gas coming out of the balloon depends on r as rᵃ and T ∝ Sᵅ Aᵝ ργ Rᵟ then
- A. a=1/2, α=1/2, β=−1, γ=+1, δ=3/2
- B. a=−1/2, α=−1/2, β=−1, γ=−1/2, δ=5/2
- C. a=−1/2, α=−1/2, β=−1, γ=1/2, δ=7/2
- D. a=1/2, α=1/2, β=−1, γ=1/2, δ=7/2
Show answer
Answer: B — a=−1/2, α=−1/2, β=−1, γ=−1/2, δ=5/2
Using dimensional analysis on T ∝ SᵅAᵝργRᵟ: [M⁰L⁰T] = [MT⁻²]ᵅ[L²]ᵝ[ML⁻³]γ[L]ᵟ. Equating powers of M, L, T and solving gives option (3): a=−1/2, α=−1/2, β=−1, γ=1/2, δ=7/2.
Q8NEET 2025Vernier Callipers / Zero Error
Consider the diameter of a spherical object being measured with the help of a Vernier callipers. Suppose its 10 Vernier scale Divisions (V.S.D.) are equal to its 9 Main Scale Divisions (M.S.D.). The least division in the M.S. is 0.1 cm and the zero of V.S. is at x = 0.1 cm when the jaws of Vernier callipers are closed. If the main scale reading for the diameter is M = 5 cm and the number of coinciding vernier division is 8, the measured diameter after zero error correction, is -
- A. 5.18 cm
- B. 5.08 cm
- C. 4.98 cm
- D. 5.00 cm
Show answer
Answer: B — 5.08 cm
Least count = 1MSD−1VSD = 0.1−(9/10×0.1) = 0.01 cm. Zero error e = +0.1 cm (positive, since VS zero is at 0.1cm). Observed reading = 5 + 8×0.01 = 5.08 cm. Corrected reading = 5.08 − 0.1 = 4.98 cm.

Practise all 71 Units and Measurements questions with a timer

Timed chapter test
Score + weak topics
Full NEET mocks & rank

Start free for 30 days

No payment, no card. Register in 2 minutes.

Q9NEET 2025Error Analysis / Percentage Error
A physical quantity P is related to four observations a,b,c and d as follows: P = a³b²/(c√d). The percentage errors of measurement in a,b,c and d are 1%, 3%, 2% and 4% respectively. The percentage error in the quantity P is -
- A. 10%
- B. 2%
- C. 13%
- D. 15%
Show answer
Answer: B — 2%
ΔP/P×100 = 3(Δa/a)+2(Δb/b)+(Δc/c)+½(Δd/d), all as percentages = 3(1%)+2(3%)+2%+½(4%) = 3+6+2+2 = 13%.
Q10NEET 2024Dimensional Analysis - Solid Angle Comparison
The quantities which have the same dimensions as those of solid angle are:
- A. strain and arc
- B. angular speed and stress
- C. strain and angle
- D. stress and angle
Show answer
Answer: B — angular speed and stress
Solid angle is dimensionless. Strain = change in configuration/original configuration = dimensionless [M⁰L⁰T⁰]. Angle = arc/radius = L/L = dimensionless [M⁰L⁰T⁰]. So strain and angle both have the same (dimensionless) dimensions as solid angle.

Practise all 71 Units and Measurements questions with a timer

Timed chapter test
Score + weak topics
Full NEET mocks & rank

Start free for 30 days

No payment, no card. Register in 2 minutes.

More NEET Physics chapters

All NEET chapters →