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Understanding LEDs

Ah, LEDs. To me, they are to electronics what fire was to the early man.

Such a simple thing. Take any coin cell battery – making sure the plus side of the battery goes with the longer leg of the LED – slide the legs of the LED over the battery and you have LIGHT!

Here’s a simple explanation on how LEDs work from reddit user speedstix:

LED’s are semiconductor technologies that are really good at converting electricity to light. There are two types of semiconductors. N-type silicon and P-type silicon. N-type silicon has excess electrons in it. P-type silicon has extra holes that electrons are drawn to. This is important to remember. Now if you sandwich N-type silicon and P-type silicon together you get something called a diode. Hence the name Light Emitting Diode (LED). Now when these two materials are sandwiched together where they meet the holes from the P-type silicon attract the electrons from the N-type silicon. (think of north and south poles of magnets and how opposites attract) This attraction creates a barrier. Now if you connect a positive DC voltage to the P-type side and the negative part of this voltage to the N-type side this barrier gets smaller and smaller and eventually electrons will jump from the P-type side to the N-type side. Remember from before these jumping electrons are what creates light. Depending on how big or small this barrier is you will get different coloured light. Also if you reverse this voltage you make the barrier bigger and bigger and no electrons will pass. This is exactly what a diode is intended to do. Only allow current to flow in one direction.

For a more detailed explanation you can go here: HowStuffWorks.com

A nice macro image of an LED via wikipedia:

(Side Note: Remember that electrons flow Cathode (-) to Anode (+), and conventional electric current flows positive to negative.)

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