Final answer:
A compass making four complete revolutions around a planar magnet indicates that the magnet has the usual two poles, a north and a south pole, since the compass will complete one cycle for each pole per revolution.
Step-by-step explanation:
The question asks about the behavior of a compass when moved around a planar magnet, and specifically, what the number of poles is if the compass makes four complete revolutions. All magnets have two poles: a north pole and a south pole. This is because magnets exhibit a dipole property, where one pole orients northward and the other orients southward. If a compass is rotated around a magnet, the north pole of the compass will point towards the magnet's south pole and vice versa, making a full circle for each pair of poles.
Despite the compass making four complete revolutions around the magnet, the magnet itself still only has two poles. The number of revolutions of the compass does not change the fundamental properties of the magnet. For every revolution, the compass points in turn towards the north pole and then the south pole of the magnet, indicating that it has passed by each pole of the magnet once per revolution.