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photocell

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photocell

Device for measuring or detecting light or other electromagnetic radiation, since its electrical state is altered by the effect of light. In a photoemissive cell, the radiation causes electrons to be emitted and a current to flow (photoelectric effect); a photovoltaic cell causes an electromotive force to be generated in the presence of light across the boundary of two substances. A photoconductive cell, which contains a semiconductor, increases its conductivity when exposed to electromagnetic radiation.

Photocells are used for photographers' exposure meters, burglar and fire alarms, automatic doors, and in solar energy arrays.
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Photocell panels on the roof detect levels of natural light and automatically dim the lights inside to compensate, thereby using the minimum energy possible and sensors inside detect movement so that lights only go on when someone is present.
Less energy for a sweet Christmas by Birmingham Mail (England)
Hinkley Lighting also equips many of these fixtures with a photocell which detects daylight and prevents the fixture from illuminating during such daylight hours.
Hinkley Eco-Friendly Indoor Lighting by Eric Marty / Home based business community
An integrated photocell activates light emitting diodes (LEDs) for even illumination up to 50 metres and for switching of the IR filter.
Vista releases bullet-proof 24-hour camera by TradeArabia (Manama, Bahrain)
 
 
 
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