When a ray of light strikes a plane mirror, the light ray reflects off the mirror.
Reflection involves a change in direction of the light ray.
The convention used to express the direction of a light ray is to indicate the angle which the light ray makes with a normal drawn to the surface of the mirror. According to the law of reflection, the angle of incidence equals the angle of reflection. These concepts are illustrated in the animation at the right. For more information on the ray nature of light, visit The Physics Classroom . Other animations can be seen at the Multimedia Physics Studios .