The figure shows a gaussian surface in the shape of a cube with edge length

The figure shows a Gaussian surface in the shape of a cube with edge length 1.40 m. What are (a) the net flux Ф through the surface and (b) the net charge qenc enclosed by the surface if E = (3.00yj) N/C, with y in meters? What are (c) Ф and (d) qenc if E = [-4.00i + (6.00 + 3.00y)j] N/C?

[arlyndajorgensen]

The corner of the box is at the origin. On the left hand side of the box, the E field is 0, (because y=0) so that face has no flux. The top, bottom, front and back do not experience flux because their area vectors are perpendicular to the E field. On the right side of the box, the E field is 1.4*3 or 4.2 N/C in the j (or y-direction), the same direction as the area vector for that face. So the net flux is the E field through the right hand side of the box times the area of that side, giving 8.23 Nm^2/C.

[mattooi]

For part a, why did you use -0.7 for y? The back corner of the cube sits at the origin, not past it into the negative direction.

[sofiasanchez-zarate]

why does a constant E make it not contribute to the flux? when it's 3y, it's still constant which is why we pulled it out the integral in part

[graysonhobbs]

thank you so much! my prof did a very poor job explaining this in class, and you made it a lot more clear and understandable.

[Qilin]

Flux on left side is negative so flux on right side will positive. Shouldn't they just cancel out?

[sneakeyboard]

I'm finding my analysis and approaches to be correct and checking your videos only to realize I somehow managed to change something when rewriting the problem.

Sigh, sometimes I think I'm dyslexic. Thanks for keeping the uploads coming anyways.

[diljeetkaursxsa]

Thanxx a lot
I got satisfaction from your explanation.

[juanjosetorres]

por que e la segunda cara usaron 0.7 sabiendo que las caras estan a 1.4 del origen