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Layman explanation of some simple EM equations

  1. Nov 20, 2015 #1
    So its been a while since I studied maxwells equations, anyway:
    So From my ignorant perspective, trying to derive conceptual meaning from these, I can see that the time dependant study there is some conductivity x the partial differential of the magnetic vector potential plus the cross product of mu*B which is H minus SOMETHING? equals the electron current density.

    I don't really remember what the magnetic vector potential is (well, that is to say, I remember not really understanding it when I tried learning about it in the first place), or the last term....or what the cross product of H is.
    I'm at a similar loss regarding the Frequeny Domain study.

    To be honest all I really remember about the cross product is that it is perpendicular to the two vectors being multiplied.

    If any one can offer a more indepth explanation of these formulas in English, I mean some maths is fine, but for a layman, that'd be great.

  2. jcsd
  3. Nov 21, 2015 #2
    These might help

  4. Nov 22, 2015 #3
    Thanks for the reply, the second vid was a good refresher about curl (and to a lesser extent divergence), The first one didn't tell me anything I didn't already remember, but it made me try and wonder how Faraday's law might fit into those equations? (given that it has a current and cross product of B in it too).
    But I'm still none the wiser about what the 'v' is in that equation (velocity?) or what the curl of H, cross product of Bxv and partial derivetive of A have to do with current density??

  5. Nov 24, 2015 #4
    So am I to assume that these equations aren't a modification/application of one specific Maxwell equation??
  6. Nov 24, 2015 #5


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    Staff: Mentor

    What is the context of those equations? Where did you see them?

    They seem to have something to do with electric and magnetic fields and electric currents in conductors. σ is the usual symbol for electrical conductivity, which is the reciprocal of resistivity: σ = 1/ρ.
  7. Nov 24, 2015 #6
    Yeah, they're from Comsol Multiphysics, depending on if you're simulating something that varies over time etc.
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