In a vernier calliper, the main scale reads in millimetres with a least count of 0.1 mm. Ten divisions on the vernier correspond to nine divisions of the main scale. Determine the least count of the calliper.

Explanation

Explanation: The Vernier principle states that two different scales are constructed on a single known length of line and the difference between them is taken for fine measurements. Determining the least count of Vernier callipers: In the Vernier calliper shown in Fig the main scale divisions (9 mm) are divided into 10 equal parts in the Vernier scale. i.e. One main scale division (MSD) = 1 mm One Vernier scale division (VSD) = 9/10 mm Least count = 1 MSD - 1 VSD = 1 mm - 9/10 mm = 0.1 mm The difference between one MSD and one VSD = 0.1 mm