Four charges each equal to \( q \) are placed at the corners of a square of side \( l \). The el...

Four charges each equal to \( q \) are placed at the corners of a square of side \( l \). The electric potential at the centre of the square is :
(A) \( \frac{1}{4 \pi \varepsilon_{0}} \frac{4 q}{l} \)
(B) \( \frac{1}{4 \pi \varepsilon_{0}} \frac{4 q}{\sqrt{2 l}} \)
(C) \( \frac{1}{\pi \varepsilon_{0}} \frac{\sqrt{2} q}{l} \)
(D) \( \frac{1}{\pi \varepsilon_{0}} \frac{2 q}{l} \)