View LEDs.pptx from ELECTRICAL 007 at The University of Lahore - Defence Road Campus, Lahore. A light-emitting diode (LED) is a semiconductor device (p-n junction diode) that emits light when an electric current is passed through it. In the case of light-emitting diodes (LEDs) fixes the colour of the light emitted by the diodes. Illustration of A light emitting diode (LED) is a two lead semiconductor light source. Image 70458308. In the case of light-emitting diodes (LEDs) Eg xes the colour of the light emitted by the diodes. LEDs are preferred light sources for short distance (local area) optical fiber network because they: are inexpensive, robust and have long life (the long life of an LED is primarily due to its being a cold device, i.e. LED (LIGHT EMITTING DIODE) A light-emitting diode (LED) is a two-lead semiconductor light source that resembles a basic pnjunction diode, except that an LED also emits light. A heated semiconductor light-emitting diode at low forward bias voltage V