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Electromagnetic Waves: A Confusing Abstraction

  1. Dec 23, 2008 #1
    I am having some trouble understanding the concept of electromagnetic waves, I suppose because I expect them to be analogous to physical waves you can see or touch (such as on a string). Yes, I know one can actually see them at visible wavelengths, but that doesn't help because I don't experience light as a wave.

    First of all, there's wavelength. This should be a physical distance, according to the units, but the question is: the distance from where in space to where?

    Someone tried explaining to me something to the effect that, if one of the fields is at its maximum strength at some point in space, the distance between that point and the next point in space at which that same maximum occurs (along the direction of propagation) determines the wavelength. Well, that raises the question of what exactly is "propagating." I'm sure my old professor would say that the fields are propagating, but that tells me nothing about the real world because the fields are just abstractions, not actual objects that can move. So, what precisely is moving along?

    Also, please help me out with the electric field of a moving charge. If we have a single charged particle just sitting somewhere, the electric field can be represented by field lines pointing outward radially. If the particle starts moving, I'm picturing those field lines picking up stakes and moving right along with it, so that, at any instant in time, the electric field is exactly the same as in the case of electrostatics. I'm guessing that's totally wrong, though.

    I think my biggest problem is my inability to tell the difference between what physics explanations are just part of an abstract model and what is actually, physically going on, or what could be detected. Of course, in a sense physics is all abstract models, but hopefully people understand what I mean when I assert that some of it is more "real" (things we can touch and see, like force or friction) than other parts of it (things that are totally made up, like fields).

    Last edited: Dec 23, 2008
  2. jcsd
  3. Dec 23, 2008 #2
    good question, I'm waiting for some answer too :biggrin:
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