The Law of Reflection

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 line drawn to the surface of the mirror. The angle of incidence is the angle between this normal line and the incident ray; the angle of reflection is the angle between this normal line and the reflected ray. According to the law of reflection, the angle of incidence equals the angle of reflection. These concepts are illustrated in the animation below.

For more information on the ray nature of light, visit The Physics Classroom Tutorial. Detailed information is available there on the following topics:

The Role of Light to Sight

The Line of Sight

The Law of Reflection

Why is an Image Formed?

Image Characteristics for Plane Mirrors

Ray Diagrams for Plane Mirrors