The refractive index of second medium with respect to the first medium is given by which formula?

Correct option is D

· The refractive index of the second medium with respect to the first medium, denoted as n21, is given by the ratio of the speed of light in the first medium (v1) to the speed of light in the second medium (v2​).
Formula:
n21 = v1/v2​​
Explanation:
· The refractive index n21​ is a measure of how much the light bends when it passes from the first medium into the second medium.
· It is defined as the ratio of the speed of light in the first medium (v1​) to the speed of light in the second medium (v2​​​).