NEETPhysicsExperimental Physics
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 ( 1 main scale division = 1 mm, 10 Vernier scale divisions = 9 main scale divisions), if the zero of the Vernier scale lies to the left of the main scale zero and the 4^ th Vernier division coincides with a main scale division, the zero error is -0.6 mm. Reason (R):
Options
- ABoth (A) and (R) are correct and (R) is the correct explanation of (A)
- BBoth (A) and (R) are correct but (R) is not the correct explanation of (A)
- C(A) is correct but (R) is not correct
- 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 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 , where N is the total number of Vernier divisions and n is the coinciding division. Zero error = -(10 - 4) 0.1 mm = -6 0.1 mm = -0.6 mm Thus, Assertion (A) is correct. Reason (R) states that the magnitude is calculated as (n LC ) , which