Two point charges $Q$ each are placed at a distance $d$ apart. A third point charge $q$ is placed at a distance $x$ from mid-point on the perpendicular bisector. The value of $x$ at which charge $q$ will experience the maximum Coulomb's force is:\\
(1) $d$\\
(2) $\frac{d}{2}$\\
(3) $\frac{d}{\sqrt{2}}$\\
(4) $\frac{d}{2\sqrt{2}}$