Calculating Electric Flux Through a Cube

[stylez03]

Electric Flux of a cube

Homework Statement

A point charge of magnitude 9.10 nC is at the center of a cube with sides of length 0.685 m.

What is the electric flux through each of the six faces of the cube?

What would be the flux Phi_1 through a face of the cube if its sides were of length 0.250 m?

Homework Equations

4*pi*Q

The Attempt at a Solution

I tried 4*pi*9.10 which equals 411 and it says I'm off by an additive constant

I know to do part2, the flux must be found for part1 but I'm not sure if I'm applying gauss's law correctly, I know that you can use symmetry to solve these cube problems but I haven't had a decent example of this type of problem and we already have homework on it.

 

[Doc Al]

Hint: What's the total flux through any closed surface that surrounds a charge Q? Once you find the total flux, then use symmetry to find the flux through each side of the cube.

 

[stylez03]

Hint: What's the total flux through any closed surface that surrounds a charge Q? Once you find the total flux, then use symmetry to find the flux through each side of the cube.

Is the flux on any surface that surrounds a charge Q => Qenclosed / Eo

 

[Doc Al]

Is the flux on any surface that surrounds a charge Q => Qenclosed / Eo

Yes it is.

 

[stylez03]

Yes it is.

Though with this, knowledge, I'm still not sure how to figure out the flux on each side of the cube.

 

[Doc Al]

Start by figuring out which side has the most flux passing through it.

 

[muchoboosto]

hummm is it Q/Eo/6?