- #1

SmartAries

- 4

- 0

- Homework Statement
- A particle with charge 5.0 micro-coulombs is placed at the corner of a cube. The total electric flux through all sides of the cube is:

A) 0

B) 7.1 * 10^4

C) 9.4 * 10^4

D) 1.4 * 10^5

E) 5.6 * 10^5

- Relevant Equations
- flux = q / epsilon

The correct answer is B, but I am not sure why.

I have a few confusions regarding this problem. First of all, I had thought that we cannot use Gauss' Law to determine the flux through a SIDE of a cube since Gauss' Law only works for SURFACES. How can we determine how an electric field pierces a 2D-line?

Next, if I interpret the word "sides" as synonymous with "faces," I get answer choice E.

flux = charge / epsilon

flux = (5.0 * 10^-6) / (8.85 * 10^-12) = 5.6 * 10^5 (which is answer choice E)

Additionally, if the charge is located at a corner of the cube, wouldn't that mean that there would only be flux through 3 faces of the cube? I think this because wouldn't the electric field lines from the charge be parallel to the three faces that are adjacent to the corner where the charge is located? If I am correct in this interpretation, then the total flux through all sides of the cube would be calculated using

flux = charge / (2 * epsilon)

because we would divide total flux by 2 since only 3 / 6 faces are being "pierced" by the electric field. If I follow through with this calculation, I do not get answer choice B.

I have attached an image of the original problem as well as a solution that I found online that I am having trouble deciphering. I would be incredibly grateful for any help; I've been stuck on this problem for hours!

I have a few confusions regarding this problem. First of all, I had thought that we cannot use Gauss' Law to determine the flux through a SIDE of a cube since Gauss' Law only works for SURFACES. How can we determine how an electric field pierces a 2D-line?

Next, if I interpret the word "sides" as synonymous with "faces," I get answer choice E.

flux = charge / epsilon

flux = (5.0 * 10^-6) / (8.85 * 10^-12) = 5.6 * 10^5 (which is answer choice E)

Additionally, if the charge is located at a corner of the cube, wouldn't that mean that there would only be flux through 3 faces of the cube? I think this because wouldn't the electric field lines from the charge be parallel to the three faces that are adjacent to the corner where the charge is located? If I am correct in this interpretation, then the total flux through all sides of the cube would be calculated using

flux = charge / (2 * epsilon)

because we would divide total flux by 2 since only 3 / 6 faces are being "pierced" by the electric field. If I follow through with this calculation, I do not get answer choice B.

I have attached an image of the original problem as well as a solution that I found online that I am having trouble deciphering. I would be incredibly grateful for any help; I've been stuck on this problem for hours!