Figure shows a small magnetised needle P placed at a point O. The arrow shows the direction of magnetic moment. The other arrows show different positions (and orientations of the magnetic moment) of another identical magnetised needle Q.

(a) In which configuration is the system not in equilibrium?
(b) In which configuration is the system in (i) stable and (ii) unstable equilibrium?
(c) Which configuration corresponds to the lowest potential energy among all the configurations shown?

Explanation

(b) (i) for stable equilibrium, the dipole moments should be parallel, examples : `AB_5 and AB_6` (ii) for unstable equilibrium, the dipole moment should be anti parallel examples : `AB_3 and AB_4`.