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?

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Answer 1 · 2018-03-26T17:14:35

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

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"#