The Crooke's Radiometer demonstrates that light has energy, and will turn its vanes even when illuminated by a torch. Despite many people thinking that the motion is caused by the impact of photons on the vanes, the Radiometer in fact operates as a heat engine, driven by the different temperatures of the black and silver vanes.

Features:

 - One piece glass body with metal vanes

 - Use as simple desk ornament

 - Great for physics demonstrations