How is light produced in an LED?
Light emitting diodes produce light by the movement of electrons between the two terminals of diode, which occur by a process called electroluminescence. When a light emitting diode is electrically connected, electrons start moving at the junction of the N-type and P-type semiconductors within the diode. When there is a jump over of electrons at the p-n junction, the electron loses a portion of its energy. In regular diodes this energy loss is in the form of heat. However, in LEDs the specific type of N and P conductors produce photons (light) instead of heat. The amount of energy lost defines the color of light produced. Refer to the Philips Lighting Academy weblink as follows for a graphical representation of this process: http://www.lighting.philips.com/main/education/lighting-academy/lighting-academy-browser/led-certification-program.html