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Homework Help: Breaking & building a charged hollow sphere

  1. Sep 1, 2011 #1
    A charged hollow sphere with surface charge density [itex]\sigma[/itex] & radius R is cut into two hemispheres...certainly the hemispheres with equal charges on them would repel each other...Now a force is applied on both the hemispheres to align them again as the original sphere..i shall be highly thankful if u could assist me finding that force applied on each hemisphere...its not a homework assignment...just a question i saw in a book...!!
  2. jcsd
  3. Sep 1, 2011 #2


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    Staff: Mentor

    Welcome to the PF.

    Interesting problem. If they were point charges, what would be the repulsive force as a function of separation discance? Once the two hemispheres are no longer in contact, what will the (formerly uniform) charge distribution be?
  4. Sep 2, 2011 #3
    How can we consider them as point charges in this problem...??
    The repulsive force between the point charges can be calculated from coulomb's law...
    I thought this about approaching this problem..

    let us take a hemisphere & we try to build another on it and see the force of repulsion due to each infinitely small ring constituting the upper hemisphere on the lower one....
    i can consider hemisphere to be build from infinite rings...
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