Question

What is dimensionless quantity? Give examples.

Answer 1

A dimensionless quantity is a physical quantity which has no physical units.

Examples of dimensionless quantity are:-

Strain is the ratio of the change in length to original length.

Poisson's ratio is the ratio of lateral strain to longitudinal strain.

Angle in radians is dimensionless add it is the two of the length of the arc to the radius.

The index of refraction is unitlesssince it is the ratio of the speed of light in a vacuum to the speed of light in a medium such as glass or a gas or a fluid.