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Four equal point charges Q each are placed in the xy plane at (0, 2), (4, 2), (4, –2) and (0, –2). The work required to put a fifth charge Q at the origin of the coordinate system will be -

1. 0 2 4 Q πε
2. 0 2 2 2 Q πε
3. 0 2 4 Q πε ⎟ ⎟ ⎠ ⎞ ⎜ ⎜ ⎝ ⎛ + 3 1 1
4. 0 2 4 Q πε ⎟ ⎟ ⎠ ⎞ ⎜ ⎜ ⎝ ⎛ + 5 1 1

Correct answer: 0 2 4 Q πε ⎟ ⎟ ⎠ ⎞ ⎜ ⎜ ⎝ ⎛ + 5 1 1

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