How LED Lighting Works
LEDs differ from incandescent and fluorescent lighting in the way that they produce light. In an incandescent lamp, a filament is heated by electric current until it glows or emits light. In a fluorescent lamp, an electrical current excites free electrons, which emit ultraviolet (UV) light. The UV light is converted after striking the phosphor coating on the inside of glass tubes, and is emitted as light.
The LED, in contrast, is a semiconductor diode. It consists of a chip of semiconducting material treated to create a structure called a p-n (positive-negative) junction. When connected to a power source, current flows from the p-side or anode to the n-side, or cathode, but not in the reverse direction. When an electron meets a hole, it drops into a lower energy level, and releases energy in the form of a photon of light. The greater the “drop” due to the semi-conductor “gap”, the greater the energy and the photon frequency emitted. Because of the way they are constructed, LEDs produce a point source light.