Question

A screw gauge gives the following readings when used to measure the diameter of a wire.
Main scale reading $:0\text{mm}$
Circular scale reading $:52$ divisions

Given that $1\text{mm}$ on main scale corresponds to $100$ divisions on the circular scale. The diameter of the wire from the above data is

• A. $0.052\text{cm}$
• B. $0.52\text{cm}$
• C. $0.026\text{cm}$
• D. $0.26\text{cm}$

Answer 1

The correct option is A $0.052\text{cm}$

Here, pitch of the screw gauge, $P=1\text{mm}$
Number of circular division, $n=100$

So, the least count, $LC=\frac{P}{n}=\frac{1}{100}=0.01\text{mm}=0.001\text{cm}$

So, diameter of the wire will be,

$d=MSR+(CSR\times LC)$

$MSR\to$Main scale reading
$CSR\to$Circular scale reading

$\therefore d=0+(52\times 0.001)=0.052\text{cm}$

Hence, option $\left(\text{A}\right)$ is correct.