A small magnetised needle P is placed at the origin of x-y plane with its magnetic moment pointing along the y -axis. Another identical magnetised…

A small magnetised needle $\displaystyle P$ is placed at the origin of $\displaystyle x-y$ plane with its magnetic moment pointing along the y -axis. Another identical magnetised needle $\displaystyle Q$ is placed in two positions, one by one. Case $\displaystyle 1$: at (a, $\displaystyle 0$) with its magnetic moment pointing along x -axis. Case $\displaystyle 2$ : at ( $\displaystyle 0, \mathrm{a}$ ) with its magnetic moment pointing along y -axis.

In which case is the potential energy of P and Q minimum ?

In which case is P and Q not in equilibrium ? Justify your answers.