Q. Four identical charges Q are fixed at the four corners of a square of side a. The electric field at a point P located symmetrically at a distance a/√2 from the center of the square is
(a) $ \displaystyle \frac{Q}{2\sqrt2 \pi \epsilon_0 a^2 } $
(b) $ \displaystyle \frac{Q}{\sqrt2 \pi \epsilon_0 a^2 } $
(c) $ \displaystyle \frac{2\sqrt2 Q }{ \pi \epsilon_0 a^2 } $
(d) $ \displaystyle \frac{\sqrt2 Q }{ \pi \epsilon_0 a^2 } $
Ans: (b)