He-1 Crookes Radiometer


To demonstrate a sensitive detector of thermal radiation.


  • Crookes radiometer
  • Desklamp

Crooke's Radiometer 1

Crookes Radiometer.


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.


Safety Notes

Crooke's Radiation SOP-13