Question

A screw gauge gives the following reading for measuring the diameter of a wire.
Main scale reading : $0\text{mm}$
Circular scale reading : $60$ divisions
Given, that $1\text{mm}$ on main scale corresponds to $100$ divisions on circular scale. The diameter of wire is,

• A. $0.050\text{cm}$
• B. $0.054\text{cm}$
• C. $0.060\text{cm}$
• D. $0.062\text{cm}$

Answer 1

The correct option is C $0.060\text{cm}$

Main scale reading $\left(MSR\right)$ = $0\text{mm}$
Circular scale reading $\left(CSR\right)$ = $60$ divison
Least count $\left(LC\right)$ of the screw gauge
$LC=\frac{\text{Value of 1 main scale division}}{\text{Total circular scale division}}$
$\Rightarrow LC=\frac{1}{100}=0.01\text{mm}$
Diameter $\left(D\right)$ of wire is,
$D=MSR+(CSR\times LC)$
$\Rightarrow D=0+(60\times 0.01)$
$=0.60\text{mm}=0.060\text{cm}$
Hence, option $\left(c\right)$ is the correct answer.