In the ray traced image to the left several polished chrome spheres reflect light from varied positions within a checkerboard tiled room.
At first we will look at a simple reflection, one that happens on a flat surface. To the left is a picture of such a situation. Here a single ray of light strikes a surface and is reflected from it.
Here are descriptions for the terms in this diagram:
Notice that the angle of incidence is equal to the angle of reflection.
The reflection of light is often discussed using phrases such as "a ray of light bounces off of a mirror." This is because when a light ray reflects at the surface of a mirror it follows a path similar in behavior to a pool ball bouncing off of a cushion on a pool table. However unusual it may sound at first, it is not really the best idea to describe the reflection of a light ray using words like bounce. Light rays, at least at first study, are best not quickly described in terms of particles, say, like pool balls. They have a wave nature. Waves are often described as turning back, not bouncing, when they reflect.
Below, in an animated diagram, a light beam reflects at the surface of a flat mirror. This diagram demonstrates the reflective behavior of any single ray of light.
Click on the picture to change the origin of the light ray. Drag slowly.
In the above diagram the reflecting surface is drawn in green, the normal is drawn in blue.
Originally this page hosted a Java applet that ran much like the above animation. You can still see that Java applet if you follow the following link: