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Homework Help: What is the potential energy of this group of electron charges?

  1. Feb 25, 2008 #1
    1. The problem statement, all variables and given/known data
    Three electrons form an equilateral triangle 1.10 nm on each side. A proton is at the center of the triangle.
    What is the potential energy of this group of charges?

    2. Relevant equations

    potential energy = U = kq1q2/r

    3. The attempt at a solution

    So, I was assuming that the three electrons, since they form an equilateral triangle, their charges will cancel out and I should just find the potential energy based on the positive charge.

    so then I substituted q1 for the proton, but then since there is a q2, i also tried to use the charge of an electron.

    also, I found the radius from the center proton of the triangle to the corner electron of the triangle to be 0.635 m

    I'm just not sure what to do anymore I only have a few attempts left
  2. jcsd
  3. Feb 25, 2008 #2
    ?? meter ??
    I will take it as 0.635 nm.:rolleyes:

    potential energy of the system=[tex]k[\frac{3e^2}{1.10X10^-9}-\frac{3e^2}{0.635X10^-9}][/tex]

    We can make three electron-electron pairs and three proton-electron pairs.
    Last edited: Feb 25, 2008
  4. Sep 20, 2011 #3

    So what am I supposed to plug in for e? +1, -1 ???????
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