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Potential energy problem , i need help !

  1. Oct 22, 2006 #1
    hello !
    i have an assignment on Electric Potential Energy , can any one help me on solving it ?
    the problem says : A small sphere with mass 2.70 g hangs by a thread between two large parallel vertical plates 5.00 cm apart.
    The plates are insulating and have uniform surface charge densities . The charge on the sphere is q = 8.80×10^−6 C .
    What potential difference between the plates will cause the thread to assume an angle of 30.0 with the vertical ?
    see the figure :P

    Attached Files:

    Last edited: Oct 22, 2006
  2. jcsd
  3. Oct 22, 2006 #2
    draw the FBD of the sphere and resolve the forces in the x and y direction
  4. Oct 22, 2006 #3
    thanx ,, i think i got the answer by drawing the diagram :
    E = Mgtan(30)
    V= E.d
    it is right ?
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