# Flux through each face on a cube

1. Apr 7, 2009

### Ed Aboud

1. The problem statement, all variables and given/known data

A point charge q is placed at one corner of a cube of edge a. What is the flux through each of the cube faces?

2. Relevant equations

3. The attempt at a solution

I drew a diagram of the situation. I'm pretty sure that I should use Gauss' Law and some symmetry arguments but I am not sure how to integrate over the cubes faces taking into account that the electric field produced by the point charge is radially outwards, like a sphere cutting through the face of the cube ( poorly described I know, sorry).

Thanks for the help.

2. Apr 7, 2009

### VKint

By Gauss's Law, the flux through the whole cube is just $$6q/\epsilon_0$$. Now, apply a simple symmetry argument to get the answer.

3. May 4, 2009

### Ed Aboud

I'm not sure why is it 6q ? If there is only one charge of magnitude 1q surely the flux is

$$q/\epsilon_0$$

4. May 4, 2009

### Staff: Mentor

Right: The total flux from that charge is just q/ε0. So what's the total flux through the cube? Through each face of the cube? (No integration needed, just symmetry.)

5. May 4, 2009