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

1. Oct 11, 2008

FourierX

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=$$\sqrt{r^{2}+h^{2}}$$ (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=$$\frac{-2Qh}{(r^{2}+h^{2})^{3/2}}$$. This is given in the book.
I have no idea where to start...

Last edited: Oct 11, 2008
2. Oct 12, 2008

Gokul43201

Staff Emeritus
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.

3. Oct 13, 2008

FourierX

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.