Question

A micrometer screw gauge with pitch of 0.5 mm and 50 divisions on circular scale is
used to measure the diameter of a thin wire. Initially when the gap is closed the line
of fourth division coincides with the reference line. Three readings show 46th, 48th
and 44th division coinciding with the reference line which is beyond 0.5 mm of the
main scale. The (best) measured value is​

Answer 1

LC=circular scale divisionspitch=500.5mm=0.01mm

Negative zero error =  −5×(0.01)mm=−0.05mm

Measured value = 0.5mm+25×0.01–(–0.05)mm=0.8mm