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Does a straight non-time-dependent E field create a circular B field?

  1. Sep 20, 2011 #1
    I was under the impression that it does, you know from Ampere's law. But today, my professor told me that Electric and Magnetic fields are very similar (although I can't imagine they are exactly the same, since there are no magnetic monopoles), THAT a non-time dependent E field does not create a circular B field. Does this mean that a current in a wire is actually a time-dependent E field?


    PS. the course that this was from was Relativistic Electrodynamics.
  2. jcsd
  3. Sep 20, 2011 #2


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    No, in this example there is no E field. It's the current in the wire that creates the B field.
  4. Sep 21, 2011 #3


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    Nevertheless, relativity tells us that there is not a seperated E and B field, but only one electromagnetic field. If you have in one frame of reference a pure electrostatic E field in another frame of reference, moving relative to the first, you have both an E and a B field. Both fields together make up the electromagnetic field. (E,B) are the components of an antisymmetric 2nd-rank tensor in Minkowski space.
  5. Sep 21, 2011 #4


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    That's quite true, but has nothing to do with the present thread. The question was, "is the current in a wire actually a time-dependent E field?" and the answer is no.
  6. Sep 22, 2011 #5
    Actually, there was at some moment an E field (for the current to be there in the first place) but no longer there is, whether one decides to attribute the B field to this E field change or to the actual current it makes no difference at all.
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