Distance travelled by linear scale of screw gauge during two full rotation of circular scale is 1mm and circular scale has 50 divisions. In an experiment to measure thickness of a plate, six divisions of main scale are clearly visible and `28^(th)` division of circular scale coincides with reference line. Moreover when studs touch each other, zero of circular scale lies 4 division below the reference line, thickness of the plate will be:

Options

A. 3.28 mm
B. 2.74 mm
C. 3.32 mm
D. 3.24 mm

Answer

D

Explanation

Pitch p = 0.5 mm
Device has +ve zero error
`R=6p+28(p)/(50)-4(p)/(50)=6p+(24p)/(50),3mm+(24)/(50)xx0.5=3.24mm`