The angle with which the light falls on the mirror (angle of incidence) is equal to the angle of reflection.

When light passes from air into glass (of the prism) the light bends away from the direction that the light entered the prism. When the light moves from the glass to air, the light bends again. This is called refraction.

If the angle at which the light enters the prism is larger than the critical angle then the light ray bends so much it reflects off the face of the prism. This is called Total Internal Reflection.

A diffraction grating is made up of many small grooves. When light enters the diffraction grating at an angle, the white light is diffracted into the light spectrum which is made up of the seven colours of the rainbow.