JEE Main · 2024 · 27 Jan 2024 · Shift 2 · Units & Measurement

WhatsApp Email
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:
  1. (A)Both (A) and (R) are correct and (R) is the correct explanation of (A)
  2. (B)Both (A) and (R) are correct but (R) is not the correct explanation of (A)✓ Correct
  3. (C)(A) is true but (R) is false
  4. (D)(A) is false but (R) is true

Answer: (B)

Solution

A positive zero error means the vernier scale reads a non-zero value with the jaws fully closed; this offset adds to every subsequent measurement, so the observed reading exceeds the true value — Assertion (A) is correct. Zero error itself arises from manufacturing tolerances or from wear and rough handling of the instrument — Reason (R) is also a true statement. But (R) explains where zero error comes from, not why a *positive* zero error specifically inflates readings (that follows from the correction rule, corrected reading = observed − zero error). So (R), though true, is not the correct explanation of (A).

JEE Main · 2024 · 27 Jan 2024 · Shift 2 · Single correct option

More JEE Main questions on Units & Measurement

  1. If ε, E and t represent the free space permittivity, electric field and time respectively, then the unit of will be :
    JEE Main 2026View solution →
  2. Keeping the significant figures in view, the sum of the physical quantities and 0.123 m is :
    JEE Main 2026View solution →
  3. A spherical body of radius and density falls freely through a viscous liquid having density and viscosity and attains a terminal velocity . Estimated maximum error in the quantity is : (Ignore errors associated with …
    JEE Main 2026View solution →
  4. Four persons measure the length of a rod as , , and . The relative error in the measurement of average length of the rod is:
    JEE Main 2026View solution →
  5. In a screw gauge, the zero of the circular scale lies 3 divisions above the horizontal pitch line when their metallic studs are brought in contact. Using this instrument thickness of a sheet is measured. If pitch scale reading is 1 mm and the circular scale reading is 51 then the …
    JEE Main 2026View solution →
  6. A ball of radius r and density dropped through a viscous liquid of density and viscosity attains its terminal velocity at time t, given by , where A is a constant and a, b, c and d are integers. The value of …
    JEE Main 2026View solution →