A licht-emitting diode (LED) is a semiconductor licht soorce. LEDs are uised as indicator lamps in mony devices an are increasingly uised for general lichtin. Appearin as practical electronic components in 1962, early LEDs emittit law-intensity reid licht, but modren versions are available athort the veesible, ultraviolet, an infrared wavelengths, wi very heich brichtness.
When a licht-emittin diode is switched on, electrons are able tae recombine wi holes within the device, releasin energy in the furm o photons. This effect is cried electroluminescence, an the colour o the licht (correspondin tae the energy o the photon) is determined bi the energy band gap o the semiconductor. An LED is eften smaa in aurie (less nor 1 mm2), an integratit optical components mey be uised tae shape its radiation pattern. LEDs hae mony advantages ower incandescent licht soorces includin lawer energy consumption, langer lifetime, improved pheesical robustness, smawer size, an faster switchin. However, LEDs pouerfu enough for room lichtin are relatively expensive, an require mair precise current an heat management nor compact fluorescent lamp soorces o comparable ootput.
Licht-emittin diodes are uised in applications as diverse as aviation lichtin, automotive lichtin, advertisin, general lightin an traffic signals. LEDs hae allaed new text, video displays, an sensors tae be developed, while thair heich switchin rates are an aa uisefu in advanced communications technology. Infrared LEDs are an aa uised in the remote control units o mony commercial products includin televisions, DVD players an ither domestic appliances. LEDs are uised tae create a new furm o wireless internet access cried Li-Fi, or licht fidelity. LEDs are an aa uised in seven-segment display.