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Light emitting diodes are designed to release energy
in the
form of photons (the most basic unit of light) in large
quantities and from only one side.
Electrical energy flowing into a light emitting diode
increases
the energy of many of the electrons in the diode momentarily.
When these electrons lose this energy, photons are
emitted.
The emitted photons bounce off the side of the plastic
case
and pass through the lens.
LEDs have no filament that needs to be heated to produce
light so they use less energy. LED lamps are also cool
and
they last a very long time.
Other sources of light (incandescent, fluorescent,
high-
pressure sodium and metal halide lamps) have filaments
that need to be heated for the lamp to start or operate.
LEDs can be made with different lenses to focus the
light in
either a narrow or a wide beam.
LED lights are especially advantageous where existing
light sources are:
High or not easily reached.
In locations where there are heavy
vibrations or
frequent impacts.
In cold temperature areas.
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