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ELECTRIC field due to a solenoid, or a current-carrying wire, or

  1. Nov 14, 2009 #1
    We always talk about the magnetic field produced by solenoids, straight wires of current, and rings of current, etc., but why do we never talk about the ELECTRIC fields produced by these geometries? I mean, there are CHARGES, right? So there must be electric fields present, right? Or am I wrong?

    I know a CHANGING magnetic field produces an electric field, but why don't STEADY currents produce electric fields?
     
  2. jcsd
  3. Nov 14, 2009 #2

    Dale

    Staff: Mentor

    This just follows directly from Maxwell's equations. With no changing B field the E field has no curl (Faraday's law), and with no net charge the E field has no divergence (Gauss' law). A field with no curl and no divergence is identically 0.
     
  4. Nov 14, 2009 #3

    jtbell

    User Avatar

    Staff: Mentor

    Current-carrying wires contain equal amounts of positive and negative charge, and are electrically neutral.
     
  5. Oct 11, 2010 #4
    well, it may be constant in general. in case of wire with conductivity sigma, there is electric field inside the wire( given by ohm's law).. although if the current is steady and the conductivity uniform the divergence of the electric field becomes ZERO.
    is the curl of electric field in this case also zero? i guess it should be because charge density in this case is constant with time everywhere.
     
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