He-1 Crookes Radiometer

Aim

To demonstrate a sensitive detector of thermal radiation.

Apparatus

  • Crookes radiometer
  • Desklamp

Crooke's Radiometer 1

Crookes Radiometer.

Description

The radiometer consists of four light mica vanes blackened on one side and silvered on the other and arranged on a common pivot so that they may rotate freely in a horizontal plane. The glass container is evacuated to a pressure of approximately 10 mm of mercury. At this pressure there are still many gas molecules to interact with the vanes and the mean free path is large.

Video