Q 11-01-036NEETJEE MainHard
A vernier callipers has a least count of $0.01\ \text{cm}$. When the jaws are closed, the zero of the vernier scale lies to the right of the zero of the main scale, and the 6th vernier division coincides with a main scale division. While measuring the diameter of a rod, the main scale reading is $2.3\ \text{cm}$ and the 4th vernier division coincides. The corrected diameter of the rod is
Answer: (C) $2.28\ \text{cm}$
Vernier zero to the right of main scale zero means a positive zero error:
$$\text{Zero error} = +6 \times 0.01 = +0.06\ \text{cm}$$
Observed reading $= 2.3 + 4\times 0.01 = 2.34\ \text{cm}$
A positive zero error is subtracted:
$$\text{Corrected reading} = 2.34 - 0.06 = 2.28\ \text{cm}$$
Solution by Sreeraj P, M.Sc Physics