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 main scale. When jaws are touching
each other, the 7th 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 3.1 cm and 3.2 cm and
4th VSD coincides with a main scale division.
The length of the cylinder is : (VSD is vernier
scale division)