What are permanent magnets ? State, briefly, an efficient way of making a permanent magnet. Write two properties to select suitable materials for making permanent magnets.

Two identical bar magnets $P$ and $Q$ are placed in two identical uniform magnetic fields as shown in Figure. Justify that both the magnets are in equilibrium. Which one of these is in stable equilibrium? Give reasons for your answer.

A small magnet of magnetic moment $M$, is placed at a distance $r$ from the origin $O$ with its axis parallel to $x$-axis as shown in Figure. A small coil, of one turn, is
placed on the $x$-axis, at the same distance from the origin, with the axis of the coil coinciding with $x$-axis. For what value of current in the coil does a small magnetic needle, kept at origin, remains undeflected? What is the direction of current in the coil?