The least count of the main scale of a vernier callipers is 1 mm. Its vernier scale is divided into 10 divisions and coincide with 9 divisions of the…

The least count of the main scale of a vernier callipers is $\displaystyle 1$ mm . Its vernier scale is divided into $\displaystyle 10$ divisions and coincide with $\displaystyle 9$ divisions of the main scale. When jaws are touching each other, the $\displaystyle 7^{\text {th }}$ division of vernier scale coincides with a division of main scale and the zero of vernier scale is lying right side of the zero of main scale. When this vernier is used to measure length of a cylinder the zero of the vernier scale between $\displaystyle 3.1$ cm and $\displaystyle 3.2$ cm and $\displaystyle 4^{\text {th }}$ VSD coincides with a main scale division. The length of the cylinder is : (VSD is vernier scale division)