Two full turns of the circular scale of a screw gauge cover a distance of `1mm` on its main scale. The total number of divisions on the circular scale is `50`. Further, it is found that the screw gauge has a zero error of `- 0.03mm`. While main scale reading of `3mm` and the number of circular scale divisions in line with the main scale as `35`. the dimeter of the wire is

Options

A. 3.32 mm
B. 3.73mm
C. 3.67mm
D. 3.38mm

Answer

(d)

Explanation

Pitch of screw gauge `=(1)/(2) mm = 0.5 mm`
Least count of screw gauge
`=(0.5)/(50) mm = 0.01mm`
Zero error = - 0.03 m
Zero correction = + 0.0 mm
Observed diameter of wire
= 3mm + 35 xx(0.01) mm = 3.35 mm
Corrected diameter of wire = (3.35 + 0.03)mm
=3.38 mm