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Electric Potential and Electric Energy

  1. May 27, 2013 #1
    1. The problem statement, all variables and given/known data
    Consider point a which is 65 cm noth of a -2.8μC point charge, and point b which is 80 cm west of the charge. Determine (a) Vba=Vb-Va, and (b) Eb-Ea (magnitude and direction)


    2. Relevant equations
    k=9x10-9
    V=kQ/r
    V=kQ(1/rb-1/ra)
    E=kQ/r2
    E=kQ(1/rb2-1/ra2)


    3. The attempt at a solution
    (a) Vba=Vb-Va
    =kQ(1/rb-1/ra)
    =(9x10-9)(-2.8x10-6)(1/0.8-1/0.65)
    =7.269x10-15 V

    (b) Eb-Ea
    =kQ(1/rb2-1/ra2)
    =(9x10-9)(-2.8x10-6)(1/0.82-1/0.652)
    =2.027x10-14 N/C

    I may have mistakes. I wonder if it's right. So I found the magnitude for (b) but I'm not quite sure about the direction (since it has a negative magnitude)? :shy:
     
    Last edited: May 27, 2013
  2. jcsd
  3. May 27, 2013 #2

    Doc Al

    User Avatar

    Staff: Mentor

    Realize that Eb and Ea are vectors. You must subtract them as vectors.
     
  4. May 27, 2013 #3
    So I have to separate them to their own X and Y components??
     
  5. May 27, 2013 #4

    Doc Al

    User Avatar

    Staff: Mentor

    Sure, that's one way of doing it.
     
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