Question

what is the principle of vernier callipers

Answer 1

The vernier calliper is based on the principle of using alignment of line segments displaced by a small amount to make fine measurements.

Answer 2

The principal used is that using two scales whose divisions differ by a small amount,we can measure this small amount.Thus,the least count is the difference between one main scale division and the Vernier scale division.Suppose that in a main scale each division is 1 mm.