How a Light Emitting Diode Works

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    Part of the video series: How to Build Electronic Circuits

    From Quick Guide: All About LED Lights

    Summary: Learn how a light emitting diode (LED) works in this free home maintenance video.

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    By Ross Safronoff
    eHow Presenter

    Ross has worked for several years in information technology, helping to maintain the servers and customer accounts that allow access to shared information. He also provided answers on...read more

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    bdlang said

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    on 12/14/2008 Nice tutorial, especially detailing the anode / cathode and explaining which direction current flows. I suggest considering adding an additional detail as to why a resistor is required when using an LED (since it's plain to see you have one inline on your breadboard).

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    Video Transcript

    " Hello! This is Ross on behalf of expertvillage.com. What is a diode? This is a light emitting diode called an LED still its like a regular diode and in sense that this is its schematic symbol except that we are going to shoot the couple of light beams out here… here. It is giving off light. Current only flows through one way. This is the cathode here and this is the anode side. When this side is more positive, when the anode side is more positive than the cathode side the current will flow through. So it allows current only flow in one direction like a valve. Here I have a circuit setup, I am going to add the light emitting diode. We not going to see any light, but I have power to it so what's going on. On the LED, there is a flat side here that flat side is the cathode, which needs to be more negative, but my circuit up here is the positive and this is the negative, so current does not flow and I am going to pull it out. I am going to turn it around to 80 degrees now the cathode will be on the negative and there we go it lights up. So now current is flowing through it, but since this is an LED it gives off light when current flows through it and that’s a diode."

    eHow Article: How a Light Emitting Diode Works

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