Q 11-01-101JEE MainJEE Main 2024 (6 Apr, Shift 1)Easy
While measuring the diameter of a wire using a screw gauge, the following readings were noted. The main scale reading is $1\ \text{mm}$ and the circular scale reading is equal to 42 divisions. The pitch of the screw gauge is $1\ \text{mm}$ and it has 100 divisions on the circular scale. The diameter of the wire is $\dfrac{x}{50}\ \text{mm}$. The value of $x$ is
Answer: (C) $71$
Least count $= \dfrac{1}{100} = 0.01\ \text{mm}$.
$$d = 1 + 42\times0.01 = 1.42\ \text{mm} = \frac{71}{50}\ \text{mm} \Rightarrow x = 71$$
Solution by Sreeraj P, M.Sc Physics