Question

Figure shows the reading obtained while measuring the diameter of a wire with a screw gauge. The screw advances by 1 division on main scale when circular head is rotated once the diameter of the wire. Find the diameter of wire ?

Answer 1

Pitch is the linear distance traveled by one complete rotation of circular scale.

Since, 1 division travel in main scale so the pitch will be 1 mm.

Least count, $LC=p/n$

Here, pitch $p=1mm$ and total number of circular divisions $n=50$

So, $LC=1/50=0.02$ $mm$

Diameter of the wire, $d=$ main scale reading ($MSR$ ) $+[$ circular scale reading ($CSD$) $\times LC]=4+[47\times 0.02]=4.94$ mm