Course: Science Subtest I
Lesson: Optics and Waves
Topic: How We See      Page 11 of 27  

A common misconception is that we can see light. Actually, we only see things that send light into our eyes, not the light itself.

In a movie theater, we do not see light on its way from the projector at the back of the room, we only see it when it hits the screen — unless it is very dusty in the theater, in which case we see the reflection from dust particles.

The fact that we do not see light itself can be demonstrated in a darkened classroom with a laser and a water mister. A laser can shine across a table without being seen. When it strikes a wall or other hard surface, we see the laser's light. When a spray bottle is used to spray water in the path of the light, the water drops scatter the light in all directions, and some of the light enters our eyes.