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Which part of the light wave do we take? (quick question)

  1. Sep 23, 2009 #1
    Hello,

    Quick question. This is a light wave

    ems.gif

    This is another light wave

    http://www.chem.yale.edu/~chem125/125/xray/DiffractionMasks/sinpositiont1.JPG [Broken]

    Why doesn't this graph have another perpendicular graph. Are they talking about the particles in the magnetic field or electric field here or both.

    Simply how do they make one wave out of a light wave that has two waves.
     

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    Last edited by a moderator: May 4, 2017
  2. jcsd
  3. Sep 23, 2009 #2

    Doc Al

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    Staff: Mentor

    While your first diagram seems like the usual depiction of an EM wave (which is what light is, classically), it's not clear what that second diagram is supposed to show. (It looks like it's meant to depict the force on some charged particle.)
    A light wave has both electric and magnetic fields, which are at right angles to each other. But that doesn't mean you always have to show both in a diagram.
     
  4. Sep 23, 2009 #3
    Thanks Doc Al!! :smile: So most of the time I think they show the electric field. When light has a particular freuqency would both electric and magnetic waves travel at that frequency. I think they do because one is created from the other.
     
  5. Sep 23, 2009 #4

    Doc Al

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    Staff: Mentor

    Yes.
     
  6. Sep 23, 2009 #5
    Thanks Doc Al :smile: Topic closed unless someone wants to start the topic if light is a wave or particle :smile:
     
  7. Sep 25, 2009 #6
    Wrong. Electric and Magnetic fields in EM waves DO NOT "create each other". Sorry Wikipedia is wrong on that. (and they won't correct it, because they are determined to keep it wrong) Electric and Magnetic fields of waves are both created by the source of the waves (moving charges) not each other.
     
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