Which configuration is widely used in circuits ?

Explanation

Potential energy of the configuration arises due to the potential energy of one dipole (say, Q) in the magnetic field due to other (P)
`Bp=(mu_0)/(4pi)(m_p)/(r^3)` (on the normal bisector )
`B_p=(mu_02)/(4pi)(m_p)/r^3` (on the axis where mp is the magnetic moment of the dipole P.
Equilibrium is stable when `m_Q` is parallel to `B_p` and when it is anti - parallel to `B_p` .
For instance for configuration `Q_3` for which Q is along the perpendicular bisector of the dipole P, the magnetic moment of Q is parallel to the magnetic field at the position 3. Hence `Q_3` is stable Thus, a. `PQ_1 and PQ_2" "` b. (i) `PQ_3,PQ_6` (stable), (ii) `PQ_5,PQ_4` (unstable) c. `PQ_6`