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Homework Help: I'm trying to find electric potential.

  1. May 3, 2015 #1
    1. The problem statement, all variables and given/known data
    There is a 4 cm by 3 cm rectangle with 2.0 nC charges at three corners. I'm trying to find the electric potential of the last corner in V.
    2. Relevant equations
    U=(kQq)/r I think
    V=(kq)/r I think
    3. The attempt at a solution
    I found the U's between the know corners but i don't know where to go from there.
  2. jcsd
  3. May 3, 2015 #2
    Hello Jace,
    You add them up :) !
  4. May 3, 2015 #3
    In this situation? I don't know if I adequately described it.
  5. May 3, 2015 #4
    I found the U's of the sides with dimensions.
  6. May 3, 2015 #5
    Aww, sorry for the mistake, There is no electric potential in the 4th corner, because there is no charge there, However you can calculate the voltage there (V) .
  7. May 3, 2015 #6
    oh....... thank you.
  8. May 3, 2015 #7
    Apparently there is because I typed in 0 and the program said I was wrong.
  9. May 3, 2015 #8
    It wants the V for that point, so where would I go from having the U's of those adjacent to it?
  10. May 3, 2015 #9
    Then, by electric potential he mean V (voltage), no charge means no electric potential energy (by intuition and the formula insists on that), however, calculate the voltage out there :)
    Last edited: May 3, 2015
  11. May 3, 2015 #10
    How would i go from U to V? What U would I use?
  12. May 3, 2015 #11
    You can't go from U to V, cuz there'there's no charge out there, but one thing you can do is use V = kQ/R
    [Edit: you can't because you'll be dividing by zero, moreover U = 0]
  13. May 3, 2015 #12
    What Q and what R?Would i use the average?
  14. May 3, 2015 #13
    R is the distance to the 4th coner, Q is the charge at each corner.
    Calculate the potential due to each charge and sum them up !
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