- To illustrate different absorption and reflection of radiation by different surfaces.
Rapid rotation is produced by heat radiation of a filament heater. (Rotation is produced by a temperature differential between the silvered and blackened surfaces, resulting in a slight gas pressure difference between the two faces). The bulb has been evacuated down to a pressure of about 1 mmHg.
Crooke's Radiometer video demonstration on Youtube
- Bill Nye the Science Guy explains the science of a radiometer