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Leds colors, just wondering...

Discussion in 'Electronic Basics' started by John Popelish, Dec 20, 2004.

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  1. It has to do with the energy per photon. Electrons gain energy by
    falling through the voltage across the junction, and give that energy
    up into a photon (if you are lucky). Blue photons have about twice as
    much energy, each, as red ones do. The junction has to be designed to
    produce the needed drop and also to be transparent to the photons
    produced. Each color requires a different kind of junction material
    and structure.
     
  2. Of course, no simplified explanation is correct. But you might search
    Google for more details, like:
    http://www.physics.gatech.edu/advancedlab/labs/photoelectric/photoelectric-3.html
     
  3. martin

    martin Guest

    Hey Ive always wondered about the voltage as related to the colors of LED's.

    Depending on the color of the Led you use a different Voltage.

    But what I don't understand is why? Aren't all leds the same with just a
    different resin or what ever plastic surrounding it to make the color. eg
    RED, or GREEN resin. I don't understand why different colors require
    different voltages.

    Can anyone answer my question ??

    Thanks.
     
  4. martin

    martin Guest

    Thanks John,

    But if I may, so your saying that the color of the LED is not caused by the
    plastic surounding the little diode device? Do they put it in a RED medium
    to enhance the color.
    What would happen if you put a Red "photon" inside a clear LED or can you
    have a clear bright photon inside a red plastic LED.

    Thanks.
     
  5. Ah. The infamous clear bright photon. I cannot wait for your explanation of
    those, John. ;)

    Jon
     
  6. The colored plastic makes it easy to tell what color light the LEDs
    will produce when they are off, and increases the on to off contrast
    in many applications. The dye darkens the appearance when no light is
    coming out.
    You get red light when it is on, and a but not internally illuminated
    object when it is off. If you are not interested in looking at the
    LED, directly, but shining a beam of red light on something else, the
    clear lenses are usually used.
     
  7. martin

    martin Guest

    Thanks John.

    Mystery solved.
     
  8. The red encased red LED should have been described as, "You get red
    glowing object when it is on, and a dark red, but not internally
    illuminated
    object, when it is off.

    I appologize for getting in a hurry. But you appear to have figured
    out where I was going.
     
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