English: A bar magnet resting on a compass board, an educational tool to show the shape of its magnetic field. The board (actually two boards placed side by side) is covered with an array of magnetic "compasses", each consisting of a magnetized steel needle in a plastic bubble which can turn freely. The compass needles turn until they are parallel to the magnetic field of the magnet at each point. It can be seen that the magnet has two locations called poles at which the magnetic field is concentrated. The magnetic field emerges from the north pole of the magnet (N) at left, curves through space to the other end of the magnet, and enters through the south pole of the magnet at right.