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A question about Volume charge density and electrostatic equilibrium

  1. Jul 9, 2011 #1
    The concept of volume charge density is an even distribution of charge over a three dimensional area. C/m^3. However, the concept of electrostatic equilibrium says that all of a conductors charge lies on the surface of the conductor.

    The existence of one seems, to me at least, to render the other pointless... Anything less then a perfect non-conductor would nearly instantly rearrange the charge towards the surface. So a volume charge density is a purely theoretical construct that will never exist. So any application of it is just in practice to demonstrate the math.

    Am I missing something?
  2. jcsd
  3. Jul 10, 2011 #2


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    Most materials are not perfect conductors.
  4. Jul 10, 2011 #3
    The question is even it is not a perfect conductor....even a lossy material, as long as electrons can flow, any electric field inside the material will cause the electrons(charges) to flow and neutralize the field.

    This is like you put a potential across a high value resistor ( say 10ee12 ohm), the moment you remove the voltage source, the potential across the resistor will immediately goes to zero. The resistor will not maintain the voltage ( field ) across by itself, electrons will stop flowing and no field is left.

    For dielectric with very low conductance, it might take longer time for the charge to move to neutralize the internal field, but it will eventually.

    This is actually a very good question.

    To the OP, volume charge density do not imply even distribution. Charge density can vary from point to point inside.
    Last edited: Jul 10, 2011
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