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Electrostatics questions

  1. Jul 27, 2014 #1
    Two questions:

    1.) Consider a hollow conductive sphere that's initially charged. These charges will distribute themselves in such a way that the condition: E-field(inside)= zero is satisfied.

    Now consider a hollow conductive sphere with a charged object inside


    The charges on the conductive sphere will have a different distribution of course. Said another way, the charges will re-distribute from the original one. But, they will do so to satisfy what condition?

    2.) You orient a straight piece of conductor on its long axis to point away from a van de graff generator (r hat)

    everyone says that conductors maintain equipotential but the two ends of the conductor you are holding are at different equipotential lines. So is there a ΔV between the conductor ends or not?

    intuition tells me that the ΔV induces an initial charge separation within the conductor.
    But, it's just that "conductors always maintain an equipotential" thing that gets me wondering.

    Thanks all
  2. jcsd
  3. Aug 3, 2014 #2

    Meir Achuz

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    1. Charges will reorient themselves keep the condition E=0 inside the conductor. If the net charge inside the cavity is Q, then a charge Q will move from the outer surface of the conductor to the inner surface.

    2. The straight conductor will develop a surface charge distribution that will keep the electric field equal to 0 inside the conductor. This will modify the field in the region of the conductor.
  4. Aug 4, 2014 #3
    If charge Q is present present inside, and Q is not at r=0 but rather shifted in position as shown in the drawing, please confirm the following

    a.) The charges on the sphere will distribute in such a way that doesn't affect the E-field inside the conductive shell. ie, within the shell, the E-field will be solely due to Q(inside) as if the shell wasn't even there.

    b.) Outside the sphere, the E-field will be non-uniform because the Q(inside) is not centered thereby making the charge distribution on the shell asymmetric.
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