Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

Homework Help: Surface Charge Distrib on Plane

  1. Mar 1, 2008 #1
    1. The problem statement, all variables and given/known data
    The plane z = 0 is charged to a density [tex]\sigma = \sigma_0 sin(\alpha x) sin(\beta y)[/tex]

    Find the potential.
    2. Relevant equations



    3. The attempt at a solution

    Well I first thing I would normally do is use Gauss's Law to find E
    [tex]E = \frac{\sigma}{2e0}[/tex] for an infinite plane, however in this case I don't appear to be able to just plug it in like that.

    My next thought would be to find the total charge Q, but how does one do that when the plane is infinite?
     
  2. jcsd
  3. Mar 1, 2008 #2
    I think you might have to use [tex]\vec{E}=-\vec{\nabla}.V[/tex], where [tex]\vec{\nabla}.V=\frac{dV}{dx}\hat{x}+\frac{dV}{dy}\hat{y}+\frac{dV}{dz}\hat{z}[/tex].

    So if you know the electric field acts in the z direction you can say that [tex]\frac{dV}{dz}=\frac{-\sigma}{2\epsilon_0}[/tex], so you can integrate w.r.t to z to find the potential. I think thats how you would do it anyway, hope this helps.
     
Share this great discussion with others via Reddit, Google+, Twitter, or Facebook