What is a LED?
LED or light-emitting diode is a semiconductor light source. LEDs can be used as indicator lights in many electronic devices, and are increasingly being used for lighting. Introduced in 1962, early LEDs emitted low-intensity red light, but modern versions are available across the visible, ultraviolet and infrared wavelengths, with very high brightness.
When a light-emitting diode is turned on, electrons recombine with electron holes within the diode, releasing energy in the form of light. This is called electroluminescence and the color of the light is determined by the energy gap of the semiconductor. A LED is often small, and optical components may be used to shape its radiation pattern. LEDs have many advantages over incandescent light sources including lower energy consumption, longer lifetime, improved robustness, smaller size, faster switching, and greater durability and reliability. The initial cost of LEDs powerful enough for room lighting are relatively expensive, but are often less expensive in the long run when energy and replacement costs of other lighting technologies are factored in.
Light-emitting diodes are used in aviation lighting, automotive lighting (particularly brake lamps, turn signals and indicators) as well as in traffic signals. The compact size, the possibility of narrow bandwidth, switching speed, and extreme reliability of LEDs has allowed new text and video displays and sensors to be developed, while their high switching rates are also useful in advanced communications technology. Infrared LEDs are also used in the remote control units of many commercial products including televisions, DVD players, and other domestic appliances.