Question

Define refractive index with reference to the law of reflection​

Answer 1

Refractive index, also called index of refraction, measure of the bending of a ray of light when passing from one medium into another. ... Refractive index is also equal to the velocity of light c of a given wavelength in empty space divided by its velocity v in a substance, or n = c/v

Answer 2

The ratio of the velocity of light in a vacuum to its velocity in a specified medium.

Law of reflection:-

also known as Snell's law defines the refractive index of a medium with respect to the other medium. First law of refraction states that, the ratio of the sine of the angle of incidence to the sine of the angle of refraction is constant.