A screw gauge gives the following reading when used to measure the diameter of a wire. Main scale reading=6mm. Circular scale reading=64 divisions. Given that 1 mm on main scale corresponds to 100 divisions of circular scale.What is the diameter of wire?

1 Answer
Mar 26, 2018

The diameter of the wire = "6.64 mm" = "0.664 cm".

Explanation:

The screw gauge has the main scale in "mm", so one rotation opens up "1 mm". But

"one rotation = 100 divisions on the cap = 1mm"

Therefore, the least count of the screw gauge = the distance moved by rotation of one div on the cap.

= (1/100) \ "mm" = "0.01 mm"

The reading of the diameter is

D = "main scale (in mm)" + "cap scale reading" xx "least count"

D = "6 mm" + (64xx 0.01 ) \ "mm"

D = "6.64 mm"