L.E.D. (Light Emitting Diode). These are forword biased p-n junction diobe which emit spontaneous radiations. When electrons fall from the higher to lower energy level containing holes, the energy is released in the form of light radiations.
Advantages of L.E.D. s are :
(i) Low operational voltage and less power.
(ii) Fast action and no warm up time required.
(iii) Long life.
