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: Where does a field line meet the surface of the conductor?

  1. Oct 11, 2008 #1
    1. The problem statement, all variables and given/known data
    In the field of a point charge over a plane, if you follow a field line that starts at the point charge in a horizontal direction, that is, parallel to the plane, where does it meet the surface of the conductor?

    2. Relevant equations
    The problem 'hint' is "You'll need Gauss' law and a simple integration."

    3. The attempt at a solution
    The electric field on the surface of the conductor at a radius R=[tex]\sqrt{r^{2}+h^{2}}[/tex] (h is the height of the pt charge, r is the x component of the radius on the plane), the Electric field due to the point charge is:
    E=[tex]\frac{-2Qh}{(r^{2}+h^{2})^{3/2}}[/tex]. This is given in the book.
    I have no idea where to start...
    Last edited: Oct 11, 2008
  2. jcsd
  3. Oct 12, 2008 #2


    User Avatar
    Staff Emeritus
    Science Advisor
    Gold Member

    Have you quoted the question exactly as it was given to you? It appears somewhat poorly written. Is this supposed to be understood in the context of a previous problem, for instance?

    Specifically, is the point charge located near an infinite, grounded conducting plane?

    Please write down the original question exactly as provided.
  4. Oct 13, 2008 #3
    the plane is grounded and i figured out that the net electric field is directed towards negative Z direction. I have to find out the distance of a point in the plane (x-axis). I thought of using a concept of projectile motion as the trajectory looks parabolic, but I am not quite sure how to get to the final conclusion.
Share this great discussion with others via Reddit, Google+, Twitter, or Facebook