Light Emitting Diode

A semiconductor device that emits incoherent narrow-spectrum light when electrically biased in the forward direction. This effect is a form of electroluminescence. The color of the emitted light depends on the composition and condition of the semiconducting material used, and can be infrared, visible or near-ultraviolet.

There are many advantages of using LEDs.

LEDs produce somewhat more light per Watt than do incandescent bulbs; this is useful in battery powered devices.

LEDs can emit light of an intended color without the use of color filters that traditional lighting methods require. This is more efficient and can lower initial costs.

The solid package of an LED can be designed to focus its light. Incandescent and fluorescent sources often require an external reflector to collect light and direct it in a usable manner.

When used in applications where dimming is required, LEDs do not change their colour tint as the current passing through them is lowered, unlike incandescent lamps, which yellow.

LEDs are built inside solid cases that protect them, unlike incandescent and discharge sources, making them extremely durable.

LEDs have an extremely long life span: upwards of 100,000 hours, twice as long as the best fluorescent bulbs and twenty times longer than the best incandescent bulbs. (Incandescent bulbs can also be made to last an extremely long time by running at lower than normal voltage, but only at a huge cost in efficiency; LEDs have a long life when operated at their rated power.)

LEDs mostly fail by dimming over time, rather than the abrupt burn-out of incandescent bulbs.

LEDs light up very quickly. A typical red indicator LED will achieve full brightness in microseconds; LEDs used in communications devices can have even faster response times.

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