Two oppositely charged identical metallic spheres, each having a mass of \(4 \mathrm{~g}\), lie on a horizontal plane, joined by a tiny insulating rod of length \(2 \mathrm{~cm}\). The magnitude of the charge on each sphere is \(3 \mu \mathrm{C}\). The rod is parallel to a uniform electric field of magnitude \(1500 \mathrm{~N} / \mathrm{C}\). Calculate the angular frequency \(\omega\) of small oscillations about the equilibrium orientation.