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Homework Help: Dielectric image charges

  1. Mar 27, 2010 #1
    1. The problem statement, all variables and given/known data

    A point charge q is a distance d from a dielectric half-space (z < 0). We will
    solve for the potential outside of the dielectric, in the region z > 0.

    (a) Away from the point charge, what equation does V satisfy? Find the bound-
    ary conditions at the dielectric surface.

    (b) Find an image charge in the dielectric slab that allows you to satisfy the
    boundary conditions. What is the potential V outside the dielectric?

    (Hint: as epsilon-naught approaches infinity, you should recover the result for a charge next to an infinite
    conducting half-space.)

    2. Relevant equations

    [tex]\sigma[/tex]= P dot n = Pz= epsilon-naught*Chi*E

    F = 1/(4*pi*ep-naught)*q*qb/(2d)^2=-1/4*pi*ep-naught*(Chi/(Chi+2))*q^2/(4*d^2))

    3. The attempt at a solution

    I know how to get the potential in the dielectric (Z<0) but I cannot get the potential above Z.

    Any help would be greatly appreciated.
    1. The problem statement, all variables and given/known data

    2. Relevant equations

    3. The attempt at a solution
  2. jcsd
  3. Mar 27, 2010 #2


    User Avatar
    Homework Helper
    Gold Member

    Okay, well how about you start by showing us that then....What does that mean the potential will be at [itex]z=0[/itex]?
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