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Movement and Properties of Light

  1. Nov 15, 2014 #1
    How exactly does light move through space in terms of EM radiation and photons. What I'm confused about is the electromagnetic field. How does it oscillate, and in which directions? Also do photons have Electromagnetic fields associated with them?
     
  2. jcsd
  3. Nov 15, 2014 #2

    Evo

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    Have you done any online research to try to answer this? Sometimes posting what you know and asking more specfic questions will help you to get answer quicker. :)
     
  4. Nov 16, 2014 #3
    Charges cause electromagnetic field to propagate outwards from them in all directions at the speed of light. If the charge changes its position, the electromagnetic field is now propagating from the new position, but the electromagnetic field from the previous position is still traveling through space.

    http://www.cabrillo.edu/~jmccullough/Applets/Flash/Electricity and Magnetism/EFieldOscillatingCharge.swf
    No. Electromagnetic fields are caused by charge. Photons do not have charge themselves.
     
  5. Nov 18, 2014 #4
    What do you mean by "the electromagnetic field from the previous position is still traveling through space"?
     
  6. Nov 18, 2014 #5

    davenn

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    you obviously didn't look at the link that was provided ;)
     
  7. Nov 18, 2014 #6

    davenn

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    So you can see that as radiating charge moves, the new radiating field moves with it, but the field that is still moving
    from the original position keeps on going

    think of this example ....

    on a simple level ( without getting into relativity) someone with a flashlight shining it at you from in front of you
    turns it off or moves it, you see it happening virtually instantly because of the high speed of the EM field ( the light) and your close proximity to its source

    now lets move further away ... say the Sun
    if it was suddenly turned off like a light globe ( your flashlight), You wouldn't know about it for 8 and a bit minutes
    The EM field ( wave) takes time to travel from the Sun to the Earth over that ~140 million kilometres. The light travelling immediately prior to the blinking out of the Sun, is still travelling across that distance

    how's that do for you ? :)
     
  8. Nov 19, 2014 #7
    That helps thanks, and sorry for not clicking the link, it wouldn't open on my phone.
     
  9. Nov 19, 2014 #8

    davenn

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    no probs :) its a good little animation

    D
     
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