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Homework Help: Potential/Charge on Concentric Conducting Shells

  1. Apr 17, 2012 #1
    I'm not 100% confident in my reasoning for this question because my answer seems unlikely:

    1. The problem statement, all variables and given/known data

    A spherical capacitor comprises two thin metal spheres of different radii but with
    a common centre. The following series of operations is completed: The spheres are mutually connected by an internal wire. The outer sphere is raised to potential +V with respect to ground. The internal connection is broken. The outer sphere is returned to ground potential. Determine the final potential and the final charge on the inner sphere.

    2. Relevant equations

    Gauss' Law (integral form)

    3. The attempt at a solution

    As the spheres are connected by a wire initially I assume when the outer sphere is raised to V the inner sphere must be too. As they are at the same potential I think the charge on the inner sphere must be 0 at this point so that there is no field between the spheres (Gauss). When the connection is broken the inner sphere must then retain 0 net charge, and so when the outer sphere is returned to ground potential i think the inner sphere must have no charge and be at 0V with respect to ground.

    This is the best argument I could come up with but I'm struggling to convince myself! Any help/confirmation of this answer would be appreciated
  2. jcsd
  3. Apr 17, 2012 #2
    It sounds reasonable to me
  4. Apr 18, 2012 #3

    rude man

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    Homework Helper
    Gold Member

    You can stop struggling now ... :approve:
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