Grades K–2 · Machines
How can a periscope show what is above a wall?
An object can be hidden by a wall while a periscope still shows it. A simple periscope has a long body with an opening near each end. Inside are two slanted mirrors.
In the diagramTwo mirrors give light a different routeWallObjectEyeUpper mirrorLower mirrorLight follows both reflections to the eye
Light from the object enters the upper opening. The top mirror sends that light down toward the lower mirror. The lower mirror sends it toward the eye.
The mirrors change the route of the light. They do not move the object or make a new one. Light still has to reach the opening for the object to be seen.
About this explanation
Starting knowledge: Recognize a mirror and follow a path between familiar objects.
Sources
- Science World — Periscopes