Homework Help: Gauss's Law

1. Oct 17, 2004

crazynut52

I've been thinking about this problem for a while now, and I cant get it to work out. A 9.6X10^-6 C point charge is at the center of a cube with sides of length .5m What is the electric Flux through one of the six faces of the cube? I know the answer is 1.81X10^5 but I cant figure out how to get there. Please Help!!

2. Oct 17, 2004

Tide

Hint 1: What would the total flux be through the entire cubic surface?

Hint 2: Invoke symmetry!

3. Oct 17, 2004

vsage

$$\oint {E \cdot dA} = \frac{q}{\epsilon_0}$$

Let's say B = the area of one side then 6B = A if A is the total surface area so...

$$\oint {E \cdot da} = \frac{q}{\epsilon_0} = 6b \times E$$

the flux through B is therefore what? (I Realize this isn't entirely correct because I am assuming E and dA are parallel but the answer remains the same through symmetry)

Last edited by a moderator: Oct 17, 2004
4. Oct 17, 2004

crazynut52

sure is easy when you figure it out... thanks for the help