UPSEE Solved Model Paper 1

When the gap is closed, without placing any object then, 10th division on circular scale coincided with reference line on main scale it means there is a zero error which is given by
Zero error = - (circular scale division X least count).
Zero error = – (10 × 0.005) = –0.05
Diameter of spherical ball
= Main scale reading + (least count × circular scale reading) + Zero error
= 8 + (0.005 × 30) + {–0.05}
= 8 + 0.15 – 0.05 = 8.10 mm
Radius of spherical ball = 8.10/2 = 4.05 mm