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Expelling an electric field?

  1. Apr 5, 2007 #1
    A superconductor repels a magnetic field by the Meissner effect. Is there a similar effect for an electric field? Note this is something different than just an insulator not allowing a current to flow.
    By the Meissner effect, if you have a hollow sphere that is superconducting and you have a permanent magnet inside it, then the magnetic field still exists inside the sphere: iron fillings on the inside would be attracted to it, etc. However, no magnetic field would be detected *outside* the superconductor from this magnet inside. And the same would hold in reverse with the permanent magnet outside the superconductor.
    Note that Gauss's law also would not allow you to accomplish this for the electric field by using a hollow perfectly conducting sphere. The effect of a charge inside a closed, hollow perfect conductor is that the charge is redistributed to the surface of the conductor. But then the electric field lines will still extend outside the perfect conductor due to this charge on the surface.
    What I'm looking for is for the electric field lines to be prevented from entering or leaving the body.


    Bob Clark
     
  2. jcsd
  3. Apr 5, 2007 #2
    This is not possible for electric lines of force.
    It is possible for magnetic ones because they are always closed lines.
    Imagine a positive charge. All lines come out of the charge to finish in a negative charge or at infinity. If you had a material with the properties you described, you could put a box of this material around the charge and forbade le lines of field to finish somewhere.
    Then this substance do not exist.
     
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