For 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 change $Q$ at the origin of the coordinate system will be
JEE MAIN 2019, Diffcult
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$W=V Q=\frac{1}{4 \pi \varepsilon_{0}} Q^{2}\left[\frac{1}{2}+\frac{1}{2}+\frac{2}{2 \sqrt{5}}\right]$

$\therefore \quad \frac{Q^{2}}{4 \pi \varepsilon_{0}}\left[1+\frac{1}{\sqrt{5}}\right]$

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