Title: Venetian Radiometer, Hand-Blown Glass Weather Tool
Shipping: $29.00
Artist: N/A
Period: Unassigned
History: N/A
Origin: Southern Europe > Italy
Condition: Museum Quality
Item Date: N/A
Item ID: 903
Venetian Radiometer, Hand-Blown Glass Weather Tool. A radiometer demonstrates the energy carried by light, and how that energy can be converted into heat. Experience this sphere powered by the sun! The vanes in the radiometer are alternately dark and light in color. When the light strikes the lighter vanes it reflects the rays while the darker vanes absorb the rays. The stronger the light, the more energy there is causing the vanes to spin faster. The radiometer vanes turn toward the light side and away from the dark side because of heated air. (The heat is generated from the light energy absorbed by the dark side of the vane.) A fascinating and beautiful science experiment, a perfect gift for brainy-types.
Link: http://en.wikipedia.org/wiki/Crookes_radiometer
The radiometer is made from a glass bulb from which much of the air has been removed to form a partial vacuum. Inside the bulb, on a low friction spindle, is a rotor with several (usually four) vertical lightweight metal vanes spaced equally around the axis. The vanes are polished or white on one side, black on the other. When exposed to sunlight, artificial light, or infrared radiation (even the heat of a hand nearby can be enough), the vanes turn with no apparent motive power, the dark sides retreating from the radiation source and the light sides advancing. Cooling the radiometer causes rotation in the opposite direction.
