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Why moving charges create tiny magnetic field?

  1. Jul 3, 2007 #1
    Dear users/moderators/administrators,

    I have been doing research about this question's answer. The magnets have magnetic property because of moving electrons which are acting like tiny magnets, and that tiny magnets are put in order so they act like one magnet. Why it is like that?

    Thank you.

    Best regards,
  2. jcsd
  3. Jul 3, 2007 #2


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    Gold Member

  4. Jul 4, 2007 #3
    No, the second not, only the first. But maybe I have one more question. How does the magnetic field "forces" the electrons to move in coil with closed circular loop (electromagnetism) and produce current?
  5. Jul 4, 2007 #4


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    Staff: Mentor

    You could very well ask the same questions about the electric field: why do charges have an electric field associated with them, and how does the electric field force another charge to move?

    In classical electrodynamics, we describe the "production" of electric and magnetic fields by charges and currents, using Maxell's Equations. We describe the electric and magnetic forces exerted by the fields, using the Lorentz force law. At the classical level, we don't have a deeper "explanation" for Maxwell's Equations and the Lorentz force law, as far as I know. We simply postulate them.

    In quantum electrodynamics (QED), we describe the interaction between charged particles by using a quantized field, whose quanta we call "photons." In principle at least, for large classical-type systems, this description should reduce to classical electrodynamics. The QED interaction is the way it is, apparently because the universe has a local U(1) gauge symmetry.

    As far as I know, that's where the chain of explanations ends at the moment. I don't think there's any generally agreed-on answer to "why does the universe have a local U(1) gauge symmetry?" Maybe string theory or some other theory at that level will give us an answer someday.
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