The Radiometer is a fascinating device that uses light to power a small light-mill. Within the glass casing of the Radiometer there is a spindle with 4 vanes, black on one side, silver on the other. The vanes will rotate when exposed to a light source and can spin continuously up to 3,000 rotations per minute.

Explaining how it works has been a matter of controversy for long. Some call it thermal transpiration. The blades of the Radiometer light-mill are encased in a clear glass bulb having a partial vacuum. When exposed to sunlight or artificial light, the vanes of the light-mill begin turning almost as if it were magic, the dark sides retreating from the radiation source and the light sides advancing. Cooling the Radiometer causes rotation in the opposite direction.

Details:

• 3" in diameter, 4 3/4" tall
• Included science experiments for a greater understanding of the principles of energy conversion
• No battery required
• Suitable for ages 8 and up!