As it moves around in a circle, we see a green spot followed by a red spot followed by a green spot and so on. You can joke about the electric company sending us some charge, then taking it back, while turning it off in the middle. The magnetic field of a bar magnet is shown by sprinkling magnetic metal filings on top of the magnet. Each filing turns into a little magnet and aligns along the magnetic field produced by the bar magnet. It is important to note that the field lines are all loops.
Magnetic fields have no beginning or end.
The field lines close to form loops within the magnet. Pocket Galvanometer Moving charges produce a magnetic field. This is shown by wrapping wires around a compass and connecting the wire across a battery. All magnetic fields arise from the motion of charges. In a permanent magnet the magnetic field is produced by the motions of electrons in the atoms of the magnet.