Four identical point charges (+4.0 ?C) are placed at the corners of a square which has 20-cm sides. How much work is required to assemble this charge arrangement starting with each of the charges a very large distance from any of the other charges?
A. +2.9 J
B. +3.9 J
C. +2.2 J
D. +4.3 J
E. +1.9 J
Answer: B
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