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Homework Help: Potential Difference from Given Efield

  1. Feb 7, 2012 #1
    1. The problem statement, all variables and given/known data
    The electric field in a region is given by E=2x^2 i +3y j where the units are in V/m. What is the potential difference from the origin to (x, y) = (2, 2) m?

    2. Relevant equations

    E = -gradient of V

    3. The attempt at a solution

    - derivative of the x-component: 2/3 x^2 from 0 to 2 = -16/3 x
    - derivative of y-component: 3/2y^2 from 0 to 2 = -6 y

    And then I added them for −11&1/3 V
    But this wrong. I'm shown the correct answer is -27 & 1/3 V

    Any tips on how that could be? Thanks !
  2. jcsd
  3. Feb 8, 2012 #2


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    Homework Helper

    It was integration, and the integral of x^2 is x^3/3, and there is no x or y after substituting x=2 and y=2.

    The result is correct however.

  4. Feb 8, 2012 #3
    Oh ,that's right! I meant integrated, sorry.

    Wait, but my answer guide says -27 & 1/3 V and the sum of my answers is −11&1/3 V ? So, how do I got from my integration to the -27 & 1/3 V? I tried just adding and, as you saw, got −11&1/3 V which was incorrect
  5. Feb 8, 2012 #4


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    Homework Helper

    The answer guides are wrong sometimes. Check if you copied the electric field correctly.

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