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The Epic Interactive Encyclopedia 1998
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Epic Interactive Encyclopedia, The - 1998 Edition (1998)(Epic Marketing).iso
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Lamp,_electric
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1992-09-03
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872b
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22 lines
device designed to convert electrical energy
into light energy.
In a filament lamp such as a light bulb an
electric current causes heating of a long
thin coil of fine high-resistance wire
enclosed at low pressure inside a glass bulb.
In order to give out a good light the wire
must glow white-hot and therefore must be
made of a metal, such as tungsten, that has a
high melting point. The efficiency of
filament lamps is low because most of the
electrical energy is converted to heat.
A fluorescent light uses an electrical
discharge or spark inside a gas-filled tube
to produce light. The inner surface of the
tube is coated with a fluorescent material
that converts the ultraviolet light generated
by the discharge into visible light. Although
a high voltage is needed to start the
discharge, these lamps are far more efficient
than filament lamps at producing light.