Unitless Quantities | MCQs

Explanation

Refractive index is both unitless and dimensionless. 

Refractive index is defined as the ratio of the speed of light in a vacuum to the speed of light in a medium.

Since both speeds have the same units (meters per second),

The units cancel out, making refractive index a dimensionless quantity.

It's also unitless because it doesn't have any associated units