to go with it. For example, if you take a bar magnet with anNpole and anSpole and break it in half, you
will get two smaller bar magnets, each of which has its ownNpole andSpole.
(There some theories that predict the existence of isolated magnetic poles, which are calledmagnetic
monopoles. These magnetic monopoles, if they exist, would take the form of subatomic particles. However,
no magnetic monopoles have yet been detected.)
30.2 Atomic View of Magnetism
Fundamentally,all magnetism is due to electric currents. On a macroscopic scale, we can construct an
electromagnetin the laboratory by running an electric current through a coil of wire. But even permanent
magnets are due to electric currents: the motion of an electron around an atomic nucleus creates an electric
current, and this electric current creates a magnetic field that ultimately manifests itself as the magnetic field
of the permanent magnet. This is described in detail in the discussion of ferromagnetism (Section 34.3). A
quantitative treatment of the magnetic field produced by an electric current is given in the next chapter.