Vernier caliper

 Vernier caliper 

A meter stick is graduate in millimeters hence it can measure a distance up to 1mm. to measure distance smaller than this other instruments are used vernier caliper is one of such instruments that can be used to measure a distance upto 0.05mm.

A vernier caliper consists off a rectangular steel bar whose one side is graduated in millimeters. This scale is known as main scale (MS). A small scale usually consisting of 10 division which slides over the main scale is known as vernier scale (VS).

This instrument has tow jaws called calipers which shown enables it to measure the internal as well as as the external diameter of a cylindrical project. A relatively this flat rod is attached to the sliding scale on back which enable it to measure the inner depth of the hollow cylinder.