Key ideas1 of 3
A ray can change direction
Refraction can happen when an electromagnetic wave passes from one material into another. In this example, a light ray enters glass from air at an angle. It bends towards the normal. The normal is an imaginary line drawn at right angles to the boundary, exactly where the ray crosses. The incident ray arrives at the boundary; the refracted ray continues into the second material. Arrowheads show the direction of travel. Use the controls to build the ray diagram one part at a time, then compare the two angles to the normal.
