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Homework Help: Electric charges at the corners of a square

  1. Nov 26, 2014 #1
    1. The problem statement, all variables and given/known data
    3 point charges, q1=+2E-9[Coulomb] are placed at the corners of a square of 0.2[m] edge. what is the potential at the center.

    2. Relevant equations
    The potential of a point charge at distance r: $$V[Volt]=K\frac{q}{r}$$
    ##K=\frac{1}{4\pi\varepsilon_0}=9\times 10^9##

    3. The attempt at a solution
    The distance from the center to each of the corners: $$r=\frac{0.1}{\cos 45^0}=0.1414[m]$$
    ##V_b=9\times 10^9\frac{2\times 10^{-9}}{0.1414}\cdot 3=382[Volt]##
    I am not sure but it should be 254[V]
  2. jcsd
  3. Nov 26, 2014 #2


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    Homework Helper

    254 would be the potential in case of two charges, or four 1E-9 C charges at each corner. The given answer must be wrong.
  4. Nov 27, 2014 #3
    Thanks, Ehild
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