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Flourecent lights question

  1. Jul 20, 2007 #1
    sorry if this is the wrong section...i really don't know where to put it. well the other night i was trying to fall asleep in my room, and it was completely dark, or close to it. and i saw this wierd glow, so i grabbed out, and pulled my flouescent lightbulb near me. I would touch it and it would glow, like very, very faintly, but it lit up whenever i touched it. Is this possible? or was it just my brain or something? is it possible that the energy from my figertips was enough to light it up?
    thanks in advance.
     
  2. jcsd
  3. Jul 20, 2007 #2

    ranger

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    It sure does happen; thanks to static electricity. It has to do with the gas in fluorescent bulbs because they are easily excited by electricity.
     
  4. Jul 20, 2007 #3

    Danger

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    Fluorescent lamps work by having a phosphor coating that converts the original UV light produced by the plasma to a visible range. Those phosphors also react to other energy input such as static electricity or even cosmic rays. Try looking at your turned-off TV in the dark, and you'll likely see the screen glowing very faintly.
    A neat thing to try is to take a piece of plastic such as a sandwich bag and rub a fluorescent tube with it. You can get a pretty decent amount of light.
     
  5. Jul 20, 2007 #4
    huh, i never knew that, thats cool. thanks for the quick replies
     
  6. Jul 20, 2007 #5

    dlgoff

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    The phosphor also has a persistency in emitting the visible light. You can see the tube glowing for a time after turning of the power.
     
  7. Jul 21, 2007 #6

    Danger

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    Good point, Digoff. I never thought of it before, but I wonder if it might be a matter of the output of one phosphor inciting a neighbour to re-emit. There could be a cascade effect.
     
  8. Jul 21, 2007 #7

    dlgoff

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    Here's what an old Modern Physics text by Robert L. Sproull says about the subject:

    He later explains how excited electrons can get trapped ("...shallow wells adjacent to the luminesecent center...") until they can get enough energy to surmount the energy barrier. This trapping/storage of energy is what is responsible for the persistence of light emitted by phosphors.

    Regards
     
    Last edited: Jul 21, 2007
  9. Jul 22, 2007 #8

    Danger

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    Cool. Thanks.
     
  10. Aug 27, 2007 #9
    o.0 nice...now i understand
     
  11. Sep 5, 2007 #10
    sounds like a good basis for low energy lazer....could be workable...??
    just a thought.
    j (compentium0)
     
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