Question

define refractive index of air? why the refractive index of other medium is taken with respect to air?

Answer 1

Answer:

Refractive index of air is the ratio of speed of light in other medium to the speed of light in air.

Refractive index of other medium is taken with respect to air because the refractive index of air is almost negligible

Answer 2

Answer: The refractive index    is the factor by which the speed of light slows down relative to the speed of light in vacuum .          

The refractive index of a vacuum is 1.0. The refractive index of air is very close to that of a vacuum, but not quite. hence the refractive index of other medium is taken with respect to air