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Self-propagating wave question

  1. Jun 3, 2007 #1
    I'm currently reading about EM waves in my physics course, but there is something that is not clear to me.

    I know, from Maxwell's equations, that a changing electric field produces a magnetic field and a changing magnetic field likewise produces an electric field. However, it seemed from my reading that the strengths of these fields were constant.

    Now, my book is talking about the self-propagation of EM waves, and from the sound of it; it would seem as if a changing electric field produces a changing magnetic field, which in turn produces a changing electric field, and so on; propagating forever.

    So, there are two things I can think of: either I am misunderstanding Maxwell's equations; or there is some other factor I am missing here in understanding what is going on. Does a changing E-field produce a changing B-field or one with a constant strength?
  2. jcsd
  3. Jun 3, 2007 #2

    Chris Hillman

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    Science Advisor

    The former, of course. There is an excellent discussion in Feynman's Lectures on Physics which should be perfect for you.
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