Eye Chart in a Plane Mirror

Brief Description

This is a simple demonstration of the distance of an image in a plane mirror. By asking a couple students to read an eye chart, first normally, then through a plane mirror, you can show that the distance between an object and its image is twice the distance between the object and the mirror.

Materials

Eye Chart and Plane Mirror.

Performing the Demo

To perform this demonstration you’ll need to ask for a volunteer. For the first part, ask the student to stand at a given point in the front of the class. Then, walk some ways away from them and hold the eye chart at your chest. Ask them to read a given line. Move closer until they can read that line. 

Next, have the student hold the eye chart, and you’ll hold a large plane mirror. Repeat the process and you should find that you are twice as close to the student as without the mirror. This is because the distance between the eye chart’s image and the student is twice the distance from them to the mirror.