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Behaviours of charges inside a conductor(slightly complex scenario?)

  1. May 1, 2014 #1
    A SPHERICAL conductor in electrostatic equilibrium has no further motion of charges within it. From this, it must imply that there is no net electric field in a conductor and this must necesssarily imply that qenclosed is zero.
    This is fairly easy to see from Gauss's law:
    (closed)∫E.dA = qenclosed0
    If E = 0, then ε0 = 0
    Assuming inside the conductor is a negative point charge, then eventual distribution will result in negative charges on the inner surface of the conductor and positive charges on the outer surface of the conductor.


    1) It is hard for me to see this visually in a more complex case such as a coaxial cable.
    2) Why is the electric field outside the SPHERICAL conductor ≠ 0 for a point outside of the conductor? If 2 oppiste charge cancels themselve at the boundary of the surface, why does there exists electric field outside the conductor?
    3) Why must excess charge reside on the surface of a conductor? What if, in the case of a coaxial cable, there are multiple layers of conductor?
    Last edited: May 1, 2014
  2. jcsd
  3. May 1, 2014 #2
    3) if there were any regions in the conductor with excess charges, a Gaussian surface around that region would have non-vanishing electric field creating an electric current contradicting the electrostatic equilibrium hypothesis
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