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Homework Help: Electric Potential Differences

  1. Feb 11, 2008 #1
    [Solved] Electric Potential Differences

    When an electron moves from A to B along an electric field line in Fig. 25-26, the electric field does 2.44*10^-19 J of work on it.


    Find the electric potential differences from VB->VA and VC->VA.

    I think the potential difference is the same for each but I'm not positive. I'm not sure what formula to use either...V2-V1= -Welec / q or V2-V1= - integral E*ds ??? If someone could get me started in the right direction I think I can figure out the rest. Thanks for your help!
    Last edited by a moderator: Apr 23, 2017
  2. jcsd
  3. Feb 11, 2008 #2
    Your guess is correct for the first part. The reason why(which is important to understand!)is in the names. If you move in the direction of an equipotential line, you're not changing your potential energy, and hence there's no work being done, in going from one equipotential to another, you change your potential energy by that much, no matter the path(ever hear that electric fields are path indepedent?)

    As for the second part, I think both equations are true, but only one is of any actual use to you. Which is it, considering what information was given?
  4. Feb 11, 2008 #3
    I think that the only thing you need to do is divide the work by the charge of electron, since potential is defined as work done on one coulomb charge. the potentials between AB and AC are the same.
  5. Feb 11, 2008 #4
    Thanks for confirming my suspicions. The negative sign was throwing me off. Found the electrical potential difference for both parts to be 1.525V. Thanks again!
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