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NEET
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NEET
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Physics
Chapter
Experimental Physics

NEET · Physics · Experimental Physics

Given below are two statements: one is labelled as Assertion (A)...

Given below are two statements: one is labelled as Assertion (A) and the other is labelled as Reason (R).

Assertion (A): For a standard Vernier calliper (11 main scale division =1= 1 mm, 1010 Vernier scale divisions =9= 9 main scale divisions), if the zero of the Vernier scale lies to the left of the main scale zero and the 4th4^{\text{th}} Vernier division coincides with a main scale division, the zero error is −0.6-0.6 mm.

Reason (R): For a negative zero error, the magnitude of the error is calculated as (n×LC)(n \times \text{LC}), where nn is the number of the coinciding Vernier division and LC\text{LC} is the least count.

In the light of the above statements, choose the most appropriate answer from the options given below:

Options

  1. ABoth (A) and (R) are correct and (R) is the correct explanation of (A)
  2. BBoth (A) and (R) are correct but (R) is not the correct explanation of (A)
  3. C(A) is correct but (R) is not correct
  4. D(A) is not correct but (R) is correct

Correct answer

C. (A) is correct but (R) is not correct

Step-by-step solution

For a standard Vernier calliper, the least count (LC) is:

LC=1 MSD−1 VSD=1 mm−0.9 mm=0.1 mm\text{LC} = 1 \text{ MSD} - 1 \text{ VSD} = 1 \text{ mm} - 0.9 \text{ mm} = 0.1 \text{ mm}

When the zero of the Vernier scale lies to the left of the main scale zero, the instrument has a negative zero error. The magnitude of a negative zero error is given by (N−n)×LC(N - n) \times \text{LC}, where NN is the total number of Vernier divisions and nn is the coinciding division.

Zero error=−(10−4)×0.1 mm=−6×0.1 mm=−0.6 mm\text{Zero error} = -(10 - 4) \times 0.1 \text{ mm} = -6 \times 0.1 \text{ mm} = -0.6 \text{ mm}

Thus, Assertion (A) is correct.

Reason (R) states that the magnitude is calculated as (n×LC)(n \times \text{LC}), which is the formula for a positive zero error, not a negative zero error. Therefore, Reason (R) is incorrect.

Hence, (A) is correct but (R) is not correct.

Answer: (A) is correct but (R) is not correct
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