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Determine the net charge contained within the cube

  1. Apr 17, 2009 #1
    1. The problem statement, all variables and given/known data
    At each point on the surface of the cube shown in the figure, the electric field is parallel to the z axis. The length of each edge of the cube is 3.7 m. On the top face of the cube = -40 N/C, and on the bottom face of the cube = +10 N/C. Determine the net charge contained within the cube.

    2. Relevant equations

    flux = E x A

    flux = charge enclosed/ permittivity constant (epsilon-naught)

    3. The attempt at a solution

    I first plugged the numbers to find the flux of the the ends of the cube, then the plugged that into the second equation to find the charge enclose, but I got a really small number that wasn't right.
  2. jcsd
  3. Apr 17, 2009 #2
    What number you got?
  4. Apr 17, 2009 #3
    -6x10^13 I meant a really big number.
  5. Apr 17, 2009 #4
    I am getting ..6. ..E-9.

    Flux is 684.5 (simply adding two together)
    and then electric constant is 8.854E-12
  6. Apr 17, 2009 #5
    Ahh, and then its negative, I didn't add the two together I was only using one. Dumb mistake, but thank you soo much!
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