# 4 charges, find potential

by jehan60188
Tags: charges, potential
 P: 204 1. The problem statement, all variables and given/known data 4 charges, distributed as follows 12*10$^{-6}$ C @ (-4,4) 12*10$^{-6}$ C @ (4,4) -6*10$^{-6}$ C @ (-4,-4) -3*10$^{-6}$ C @ (4,-4) Calculate the potential at the origin if the potential at infinity is zero. 2. Relevant equations V= U/q = -W/q = ∫E*dl = k*q/r for multiple point charges, find V for each one, and sum them up 3. The attempt at a solution $V1 = V2 = \frac{k*12*10^{-6}}{(4*\sqrt{2}/2)}$ $V3 = \frac{k*-6*10^{-6}}{(4*\sqrt{2}/2)}$ $V4 = \frac{k*-3*10^{-6}}{(4*\sqrt{2}/2)}$ $V1+V2+V3+V4 = \frac{k*3*10^{-6}}{4*\frac{\sqrt{2}}{2}}*(4+4-2-1) = 47676.7$ So, I factor out the k, the 3*10e-6, and the 1/(r) from each Vi, then multiply it by 4+4-2-1 =5 this answer is not right. Any pointers? thanks!]
 Sci Advisor HW Helper Thanks P: 26,148 hi jehan60188! shouldn't r be 4√2 ?
P: 204
 Quote by tiny-tim hi jehan60188! shouldn't r be 4√2 ?

4^2 + 4^2 = 32 = 4 Sqrt(2)
why, WHY did I divide by 2?!

divided my solution by 2 (since it was sqrt(2)/2 in the divisor), and got the right answer! thanks!

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