Question

any 3 point if diff b/w absolute and relative refractive index

Answer 1

The absolute refractive index (μ) of a medium is the ratio of the speed of light in vacuum (c) to the speed of light in that medium (v), i.e. μ = c/v.

The refractive index of medium 2 with respect to medium 1 is the ratio of the speed of light in medium 1 to that in medium 2.  i.e., μ21 = v1/v2.