Interactions of Light Waves

Refraction

The bending of a wave as it passes at an angle from one substance, or material, to another is called refraction. Refraction of lught waves occurs becuase the speed of light differs depending on the material through which the waves travel through. Light travels slowly through matter. When a wave enters a new material at an angle, the part of the wave that enters first begins traveling at a different speed from that of the rest of the wave.

When light passes into a material where the speed of light is slower, the light bends away from the boundary between the materials.

When light passes into a material where the speed of light is faster, the light bends toward the boundary.

A prism is a piece of glass that separates white light into the colors of visible by refraction. 

If light passes through a prism it will be refracted twice - once when it enters and another when it exits.