Light rays

Learning objectives

To illustrate that light is invisible! The ray model of light is just a very useful physical model
To illustrate that we often consider just a few significant rays among the infinite number of them.

Since light moves in straight lines, and because it is not visible, we can draw a line with an arrowhead to represent how the light behaves. Doing so illustrates the ray model of light. The “rays” are represented as line segments leaving primary or secondary sources, and travelling without interruption until they encounter an obstacle. Because it is not possible to draw an infinite number of lines, we sometime draw a beam of light.