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Homework Help: Electric Potential in a region of space

  1. Nov 6, 2008 #1
    1. The problem statement, all variables and given/known data
    The electric potential in a region of space is
    render?texml=V+%3D+%5Cfrac%7B350%7D%7B%5Csqrt+%7Bx%5E2+%2B+y%5E2+%7D%7D.gif
    , where x and y are in meters. What is the strength of the electric field at (x,y)=(2.1m,2.7m)?
    The electric force is in V/m.

    2. Relevant equations
    E = -grad(V)
    E = -dV/ds

    3. The attempt at a solution

    I know that i have to find the partial derivatives of the x and the y but im not sure on how to get the answer from the equation given. I was thinking of making the square root into the exponential of 1/2 and then raising that to -1 to get ride of the fraction and then taking the derivatives of that but i keep getting the wrong answer. Anybody have suggestions of help they can give me please. Thanks.
     
  2. jcsd
  3. Nov 6, 2008 #2

    tiny-tim

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    Welcome to PF!

    Hi quietriot1006! Welcome to PF! :smile:

    (btw, please use the LaTeX provided, rather than importing images of equations)

    Just use the Chain Rule for differentiation …

    you know how to differentiate 1/√x, don't you? :wink:
     
  4. Nov 7, 2008 #3
    Thanks for the welcome. Im still not getting the answer. Maybe im doing the chain rule incorrectly. What would i use for u or g(x) and h(x)?
     
  5. Nov 7, 2008 #4

    tiny-tim

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    (x2 + y2) :smile:
     
  6. Nov 9, 2008 #5
    I keep getting the same asnwer, -127 V/M and its not the right answer. What else can i do?
     
  7. Nov 10, 2008 #6

    tiny-tim

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    Show us your calculations, and then we can see where the mistake is. :smile:
     
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