Physics Dept. Demonstration Manual

DHT15 - Crooke's Radiometer

Objective: To illustrate different absorption and reflection of radiation by different surfaces.

 

Apparatus:  
  • Crooke's radiometer
  • Filament heater

Method:

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.