Question

why does a Ray of light travelling from one medium to another change it path?​

Answer 1

Answer: The bending of light as it passes from one medium to another is called refraction. The angle and wavelength at which the light enters a substance and the density of that substance determine how much the light is refracted.

Answer 2

A ray of light travelling from one medium to another change its path because of 'refraction' of light. If it passes from a rarer medium to denser medium then the path of light bends towards the normal. And if the light is passing through a denser medium to a rarer one then the path of light bends away from the normal.