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Homework Help: Calculate flux through face of a cube

  1. Sep 12, 2013 #1
    1. The problem statement, all variables and given/known data

    A point charge q is located at the corner of a cube with edges of length
    L. Find the electric flux through the shaded face at y = L.

    2. Relevant equations

    Gauss's Law; flux = ∫E[itex]\bullet[/itex]n dA = qenc

    3. The attempt at a solution

    Here's what I'm thinking. In the problem statement, the charge q is located at a corner of the cube. I can't use Gauss's Law, due to lack of symmetry. However, I can draw a bigger cube instead, whose center is at the location of the charge. Then I have symmetry to use Gauss's law and say that the flux through the whole cube is q/ε. The face whose flux the problem wants me to calculate is now just 1/24 of the surface area of the whole (bigger) cube. Therefore I can say that the flux through the original face is just q/(24ε).

    Is this correct, or am I just trying to be too clever by half, as they say?
    Last edited: Sep 12, 2013
  2. jcsd
  3. Sep 12, 2013 #2
    This is correct and in fact is the manner in which the problem is solved in the solution manual. Good job!
  4. Sep 12, 2013 #3
    Nice! Seemed a bit too good to be true. :)
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