If a ray of light passes from medium I to medium II without any change of direction, what can be said about the refractive indices of these media.

55 What is meant by refraction? 56 Express the refractive index of the medium. 58 Mention two properties of a wave: one property which varies and the other which remains constant when the wave passes from one medium to another. 59 Name one factor on which the direction of bending of a ray of light depends.