6A20.30: Light Bulb Illusion
Description: A concave mirror is used to project a real image of a light bulb onto an empty socket.
Empty glass frames can be setup to help students position their heads. Just have them look though the glasses.
- Light bulb illusion apparatus
- Light bulb
- Black cloth.
- There are many different ways of going about this demo. Listed here are the two most common.
- Turn on the light. Position it so the mirros is not facing the class.
- Ask students if they can see the light bulb in the empty socket.
- They can't because there is no light bulb in the socket.
- Turn off the room lights.
- Now turn it so the mirror faces the class. You may have to move it slowly around the room so everyone can see it.
- The students now see the image of a light bulb in the light socket.
Note: If necessary, adjust mirror angle and bulb location to get the real image to sit in the empty socket.
- With the light bulb in the light socket, turn on the apparatus.
- Cover the mirro with the black cloth, but leave it so the light bulb on top stay illuminated.
- Show students that the top light bulb is lit.
- Take out the light, making sure to cover it with either your hand or body (so they don't see it never went off).
- You can say something cleaver here.
- Wet your finger and stick it in the top light socket.
- You can make a scream or something to give the kids a scare.
- When finished, show the students the apparatus and the image of the light bulb in the empty socket.