6B40.10: Light on a Variac (Black body radiation)
Description: Use to show that radiated color changes with temperature.
- Overhead projector light
- Variac to banana plug cable
- Table clamp
- S clamp
- Medium length rod
- Mount the light on a pole and attach to a table.
- Connect the light to the variac.
- Test to make sure it works.
- Turn off most (or all) of the room lights.
- Turn on the projector light.
- Slowly increase the voltage and note the change in color of the bulb.
It will start off as a dark orange, and progress its way to a bright white.
- Do not leave the light on for very long since it gets very hot and can break. When finished, turn the light off.