how to use vernier caliper?

Vernier Scale is used to measure the length of an object or the outer diameter of a cylindrical object.

It has a main scale and a smaller scale called the Vernier scale that slides over the main scale. This instrument has two pairs of jaws that are used to hold objects to be measured.

The object to be measured is fixed between the two jaws, lengthwise for length measurement. If measuring diameter, the cylindrical side of the object should be fixed between the two jaws. To measure the inner diameter of a cylindrical object, that object should be fixed over the smaller upper jaws, with the jaws touching the inside walls of the object.

To obtain the correct measurement with a Vernier caliper we have to first find the least count of the instrument.

You also have to determine the zero error of the instrument.

The observed reading will be the main scale reading added to the product of the Vernier scale reading and the least count.

The true measurement will then have to account for the zero error. So, the final measurement will be the observed reading ± the zero correction.