Reflexion and Diffusion

When light hits a surface, e.g. a mirror, it is reflected. This process is called "reflexion". The angle between the incoming ray of light and the normal (in the image: a) as well as the angle between the outgoing ray of light and the normal (in the image: ß) are equal. (The normal is a line perpendicular to the surface that runs through the point where the reflexion happens.)

The Law of reflexion says: α = β

The incoming light ray, the normal and the reflected light ray are on the same level.