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Finding a light source that produces an absorption spectrum?

  1. Nov 23, 2012 #1
    This is an observational exercise where I have to find several different light sources and observe their spectra through a diffraction grating, then record my observations. I need two sources of each (i.e. continuous, emission, absorption).

    Continuous and emission are fairly easy, but for the life of me I can't think what I could observe that would produce an absorption spectrum. I know that absorption spectra come about when there is an absorbing material like cool gas in front of a black body but I don't really know how I could find something like that. I thought maybe if I looked at a light source from far away in cold weather that might do it, but I still didn't see an absorption spectrum. Any help or hints would be much appreciated!
     
    Last edited: Nov 23, 2012
  2. jcsd
  3. Nov 24, 2012 #2

    ehild

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    The sun itself produces absorption spectrum of its outer atmosphere: http://en.wikipedia.org/wiki/Fraunhofer_lines.

    You can make a "light source" showing absorption spectrum by placing a coloured liquid (solution of some dye, or solution of KMnO4...) in front of a simple tungsten lamp.

    ehild
     
  4. Nov 24, 2012 #3
    Brilliant, thanks! I hadn't thought of that. I feel a bit stupid now.
     
  5. Nov 24, 2012 #4

    ehild

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    Or it can be a colour filter glass or a simple coloured glass in front of the tungsten lamp... :smile:


    ehild
     
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