An electric dipole of moment P→ is placed in a uniform electric field E→ such that P→ points alongE→. If the dipole is slightly rotated about an axis perpendicular to the plane containing E→ and P→ and passing through the centre of the dipole, the dipole executes simple harmonic motion. Consider  I to be the moment of inertia of the dipole about the axis of rotation. What is the time period of such oscillation