Question

Two full turns of the circular scale of a screw gauge cover a distance of 1 mm 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 -0.03 mm while measuring the diameter of a thin wire, a student notes the main scale reading of 3 mm and the number of circular scale divisions in line with the main scale as 35. The diameter of the wire is:

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

Answer 1

The correct option is D 3.38 mm

Diameter = M.S.R. + C.S.R x L.C + Z.E.
$=3+35\times \frac{0.5}{50}+0.03=3.38mm$