Here's the problem I am having trouble with, even though i think it should be simple...(adsbygoogle = window.adsbygoogle || []).push({});

Four identical charges (+3.5uC each) are brought from infinity and fixed to a straight line. The charges are located .35m apart. Determine the electric potential energy of the group.

So I've tried two different approaches. First, I found every possible combination of the 4 charges (q1q2 q1q3 q1q4 q2q1 q2q3 q2q4 q3q1 q3q2 q3q4 q4q1 q4q2 q4q3) and used the equation U = kqq/r to find the potential for all 12 combos and found the sum of all 12 potentials. This didn't give me the right answer.

So then I tried just the combinations that were totally different (q1q2 q1q3 q1q4 q2q3 q2q4 q3q4) and found the sum of the potentials, and that did not give me the correct answer either...

Any comments? Thanks in advance

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# Homework Help: Electric Potential Difference and charges

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