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Homework Help: Electric potential in relation to electric field problem

  1. Mar 5, 2008 #1
    1. The problem statement, all variables and given/known data

    The electric potential in a region of uniform electric field is -1000 V at x = -0.900 m and + 1400 V at x = + 2.00 m. What is E_{x} ?

    2. Relevant equations

    v= integral of E dot ds

    3. The attempt at a solution

    i am thinking i will use the equation V=Ed, so I would use V=-1000 and d equal to -.9m
    then i have no idea what to do from there, any help is appreciated. thank you
  2. jcsd
  3. Mar 5, 2008 #2


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    Homework Helper

    This is the right direction. For a potential which only changes along one dimension, you can write E = -dV/dx ; that is, the magnitude of the field is the slope of the potential function and the direction of the field runs from higher to lower potential. (This is basically where V = Ed comes from, for the case of a uniform field.)

    BTW, in that formula, d is the separation between the two points over which the potential change is measured, not a position.

    So you have two values of the electric potential at two values of x. What is the slope of this (linear) function? What is the direction of the electric field?
    Last edited: Mar 5, 2008
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