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Point charge and electric potential

  1. Jun 20, 2007 #1
    1. The problem statement, all variables and given/known data
    three point charges, each of 10^-9 are located at 3 corners of a square of side 20cm. Calculate the electric potential at the forth corner.

    2. Relevant equations

    V = Q / (4(pi)(epsilon 0) r)

    3. The attempt at a solution

    Potential because of corner A = 10^-9 / (4 (pi) (epsilon 0) 0.2)

    = 44.96

    Potential because of corner B = 10^-9 / (4 (pi) (epsilon 0) 0.2)

    = 44.96

    Potential because of corner C = 10^-9 / (4 (pi) (epsilon 0) 0.284)

    = 31.66

    A + B + C = 121.58

    Is this correct, finding the potential from each point charge individualy?

    Also there is another question very similar to this where there are 4 point charges on the corners of a square, and we need to find the potential at the centre, would i do this the same as above, (providing what i did above is correct.
  2. jcsd
  3. Jun 20, 2007 #2


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    Science Advisor
    Homework Helper
    Gold Member

    Yes, it's correct (you should put the units on your answers, though!!). I get a slightly different value for the distance for the third chare (0.2828 m which is approximately 0.283) . You are doing it the right way: finding the potential due to each charge and then adding all the results.
  4. Jun 20, 2007 #3
    thank you.

    i think it was a typing error lol.
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