Reflection of Light

Reflection of light is the return of light into the same medium after it strikes a surface. When a ray of light reaches a mirror, part of the light can be reflected back. The incoming ray is called the incident ray, and the returning ray is called the reflected ray.

A **normal** is an imaginary line drawn perpendicular to the reflecting surface at the point where the incident ray strikes it. Angles in reflection are measured from the normal, not from the mirror surface.

The angle between the incident ray and the normal is called the **angle of incidence, represented by i**.

The angle between the reflected ray and the normal is called the **angle of reflection**, represented by **r**.

The first law states: Angle of incidence = Angle of reflection **i = r** The second law states that the incident ray, reflected ray, and normal all lie in the same plane.

A smooth surface such as a plane mirror reflects parallel incident rays in an orderly way. This is called **regular or specular reflection**. It can produce a clear image.

A rough surface reflects incoming light in many different directions because different parts of the surface have different orientations. This is called **diffuse reflection**. The law of reflection still applies at each small part of the surface.

A plane mirror produces an image that is: * virtual; * upright; * approximately the same size as the object; * laterally inverted; * as far behind the mirror as the object is in front.