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Units and Measurements

17 NEET questions on Units and Measurements. A sample is shown below with full explanations; the rest are available free after signing up.

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Units and Measurements2025medium

Q1.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

  • A5.18 cm
  • B5.08 cm
  • C4.98 cmAnswer
  • D5.00 cm

Explanation

The least count is 1 MSD − 1 VSD = 0.1 x (1 − 9/10) = 0.01 cm, so the observed reading is 5 + 8 x 0.01 = 5.08 cm. The jaws read +0.1 cm when closed, a positive zero error that must be subtracted, leaving 4.98 cm.

Source: NEET 2025 (4 May), Code 45, Q25

Units and Measurements2025easy

Q2.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

  • A10%
  • B2%
  • C13%Answer
  • D15%

Explanation

Relative errors add, each weighted by the magnitude of its exponent — the sign of the exponent is ignored because this is the maximum possible error. So the error in P is 3(1%) + 2(3%) + 1(2%) + (1/2)(4%) = 3 + 6 + 2 + 2 = 13%.

Source: NEET 2025 (4 May), Code 45, Q42

Units and Measurements2026medium

Q3.Which of the following measurements require 'index correction'?

  • AMeasurement of resistance of a wire using meter bridge
  • BMeasurement of gravitational acceleration using simple pendulum
  • CMeasurement of focal length of lenses using optical benchAnswer
  • DMeasurement of speed of sound using resonance tube

Explanation

Index correction allows for the gap between the index mark on an optical-bench carriage and the actual position of the lens, object or screen it carries — the scale reading and the optical position are not the same point. That offset is peculiar to optical-bench work; the other three experiments have no equivalent.

Source: NEET 2026 re-exam (21 June), Code 50, Q20

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Questions are reformatted from NEET previous year papers with original explanations and topic tagging. NEET Prep is not affiliated with the NEET examining body.