A dipole with two electric charges of $ 2 \, \mu C $ magnitude each, with separation distance $ 0.5 \, \mu m $, is placed between the plates of a capacitor such that its axis is parallel to an electric field established between the plates when a potential difference of $ 5 \, V $ is applied. Separation between the plates is $ 0.5 \, mm $. If the dipole is rotated by $ 30^\circ $ from the axis, it tends to realign in the direction due to a torque. The value of torque is :