Question

Define the least count of a screw gauge.

Answer 1

1. For precise measurement of spherical or a cylindrical object, a screw gauge is the best instrument. An extremely fine-tuned screw gauge can be a bit difficult for untrained hands to use.
2. Least count: The least count of the screw is defined as the distance moved by the tip of the screw when turned through one division of the head scale.
   Least count (LC) of the screw gauge = $\frac{\left(pitch\right)}{(totalno.ofdivisionsonthecircularscale)}$
3. Micrometre screw gauge is defined as an instrument that is used for measuring the diameter of thin wires, the thickness of small sheets such as glass or plastics.
   Least count of micrometre =$\frac{\left(pitch\right)}{(totalno.ofdivisionsonthecircularscale)}$
   Least count of micrometre = $\frac{1mm}{100}$
   = $0.01mm.$
   Therefore, Least count of micrometre screw gauge = $0.01mm$.