Question

cause of refraction​

Answer 1

This change of direction is caused by a change in speed. For example, when light travels from air into water, it slows down, causing it to continue to travel at a different angle or direction. ... Change in speed – if a substancecauses the light to speed up or slow down more, it will refract (bend) more.

Answer 2

When a ray of light passes from one medium to another medium,its direction  or path changes because of the change in speed of light from one medium to another medium.