The radiometer is made from a glass bulb from which much of the air has been removed to form a partial vacuum. Inside the … See more

When a radiant energy source is directed at a Crookes radiometer, the radiometer becomes a heat engine. The operation of a heat engine is based on a difference in temperature that is converted to a mechanica… See more

Over the years, there have been many attempts to explain how a Crookes radiometer works:
Crookes incorrectly suggested that the force was due to the pressure of light. This theory was … See more

To rotate, a light mill does not have to be coated with different colors across each vane. In 2009, researchers at the University of Texas, Austin created a monocolored light mill which has four curved vanes; each vane forms … See more

The thermal creep from the hot side of a vane to the cold side has been demonstrated in a mill with horizontal vanes that have a two-tone surface with a black half and a white half. This design is called a Hettner rad… See more