The erros that always occur in the measurement with screw gauge is

Define least count of a screw gauge.

How can we increase the relative accuracy of measurement by a screw gauge ?

Find the ratio of the smallest measurements possible on a screw gauge to verneir calipers.

Diagrams show readings of a screw gauge. Figure (i) shows the zero error reading when the screw gauge is closed, figure (ii) the reading when the screw gauge is being used to measure the diameter of a ball-bearing. What is the diameter of the ball-earing ? There are 50 divisions on circular scale.

Name the principle on which screw gauge works.