How is the refractive index of a medium related to the speed of light? Obtain an expression for refractive index of a medium with respect to another in terms of speed of light in these two media?

Explanation

The refractive index of the medium `n_m` is given by
`n_m = ("Speed of light in air")/("Speed of light in medium") =c/v`
Let `v_1` be the speed of light in medium 1 and `v_2` be the speed of light in medium 2. The refractive index of medium 2 with respect to medium 1 is given by the ratio of the speed of light in medium 1 and the speed of light in medium 2. This is usually represented by the symbol `n_(21)`
`n_(21) =("Speed of light in medium 1")/("Speed of light in medium 2") =(v_1)/(v_2)`