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Homework Help: Force on a sphere in a constant external electric field

  1. Feb 8, 2009 #1
    1. The problem statement, all variables and given/known data
    An uncharged solid sphere is paced in a constant external electric field E0. What is the force on the sphere?


    2. Relevant equations



    3. The attempt at a solution
    I know ( already have found ) the electric potential and electric field around the sphere. Also worked out the surface charged density. I don't know how to calculate the force..Any help please?
     
  2. jcsd
  3. Feb 8, 2009 #2

    LowlyPion

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    Isn't F = q*E ?
     
  4. Feb 9, 2009 #3
    It seemed too simple somehow... Is q the induced charge on the sphere, and E the electric field close to the sphere??

    Thank you for your help
     
  5. Feb 9, 2009 #4

    LowlyPion

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    If there is charge separation, what will the net force be?
     
  6. Feb 9, 2009 #5
    Got it! Thanks a lot for the help!!
     
  7. May 21, 2009 #6
    This is the exact question i was looking for help with and still not sure of what the next step is.

    I know the uniform E-field causes the sphere to gain an induced dipole. From this how do you get the force? Is it ok to just assume the E-field remains uniform.. this can't be right as there would then be no force and seems there must be a force from the way the question is worded.
     
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