LIGHT EMITTING DIODES Commanly called LED’s are real unsung heroes in the electronic world. They do dozens of different jobs and are found in all kinds of devices. Among other they form the numbers on digital clocks, transmit information from remote controls, light up mutches, and tell you when your appliances on.

Basically, LED’s are just tiny light bulbs that ft easity in to on electrical circuit. But unlike ordinary indescent bulbs. They don’t have a filament that will burn out, and they don’t get especiallty hot. They are illuminated solely by the movement of the electrons in a semiconductor materials and they lost as long as a standart transistor

WHAT CAUSES THE LED TO EMIT LIGHT AND WHAT DETERMINES THE COLOR FLIGHT

When sufficent voltage is applied to the chip across the leads of the LED, electrons can move easily in only one direction across the function between the P and N regions. When a voltage is applied and the current starts to flow, electrons in the N region have sufficient energy to move across the junction in to P region, in the P region the electrons are immediately attracted to the positive charges due to the mutual coulomb forces of attraction between opposite electric charges.

When an electron moves sufficiently close to a positive charge in the P region, the two charges “recombine”

Each time an electron recombines with a positive charge Electric potential energy is converted into electromagnetic energy. For each combination of negative and a positive charge a quantum of electro magnetic energy is emitted in the form of photon of light with a frequency characteristic of the semiconductor material. Only photons in a very narrow frequency range can be emitted by any material LED that emit different colors are made of different semi-conductor materials and require different energies to light them.