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White light to different colors

  1. Feb 1, 2013 #1

    I have a question, when shining a flash light (white light) we are getting all the visible spectrum of light correct; the wavelengths are under 400 to above 700 nm ? now if we put a red or blue plastic sheet on top of the flash light we see the color of that plastic sheet.

    What is happening to the light? say we put a clear red plastic sheet on the flash light, so the light that is coming out of the other side has a wavelength of 700 - 750 nm ?
  2. jcsd
  3. Feb 1, 2013 #2

    I like Serena

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    Hi fouad89! :smile:

    I'm afraid a flash light doesn't give all of the visible spectrum of light.
    It only stimulates the 3 types of cones in your eyes to create the illusion of white light.

    If you put a red plastic sheet over the flash light, that plastic sheet will absorb (or reflect) the visible light that is not red, and allow red through (which is 620 nm and up).
    Whether it lets non-visible light through is not known.
    You'd need more information on the plastic to be able to tell.
  4. Feb 1, 2013 #3
    ok thanks
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