LED's

An LED is a layered semiconducting device. Electrons crossing the p-n junction barrier potential give up some or all of their energy - not as thermal energy (heat) but as a light photon. LED's are infrared, red, green or blue depending on the band (energy) gap.

The white LED's shown actual size are blue LED's with a phosphor that emits white light when excited. They are 98% efficient, have a life of 50 years and will eventually replace old style light bulbs. 

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