Refraction (अपवर्तन) is the change in direction of a propagating wave as they pass from one medium to another, due to a change in their speed. The phenomenon is most commonly associated with light, sound and even water waves.
Snell’s Law predicts how the ray will change direction as it passes from one medium into another. The amount of bending, or angle of refraction, of the light wave depends on how much the material slows down the light.
Note: Light moves at about 124,000,000 meters per second (less than half the speed in a vacuum) in a diamond. Diamonds have a higher index of refraction than water or air.
The most common example used when discussing refraction is a straw in water. When a straw is placed in a glass of water and viewed from the side, it appears to be broken or bent. This is due to the difference in the refractive indices of air and water.
Interesting Refraction Phenomena
Dispersion of Light by Prisms