Question

If the 47^th division of the circular scale coincides with the zero of the main scale of a screw gauge of least count 0.01 mm and having 50 circular divisions, what is it's zero error?

Answer 1

In this case, the zero error is negative
Least count of screw gauge = 0.01 mm
Thus, zero error = (50-47) X L.C.
= 3 X 0.01
= 0.03 mm