JEE Main 2025 — Electrostatics Question with Solution

In the first configuration (1) as shown in the figure, four identical charges $\left(q_0\right)$ are kept at the corners A, B, C and D of square of side length ' $a$ '. In the second configuration (2), the same charges are shifted to mid points $G,E,H$ and $F$, of the square. If $K=\frac{1}{4\pi {ϵ}_0}$, the difference between the potential energies of configuration (2) and (1) is given by :