A current loop has two distinct sides. Bar magnets also have two distinct sides or ends, so you might wonder if current loops are related to these permanent magnets. Consider the following experiments with a current loop. Notice that we’re showing the magnetic field only in the plane of the loop.

These investigations show that a current loop is a magnet, just like a permanent magnet. A magnet created by a current in a coil of wire is called an electromagnet. An electromagnet picks up small pieces of iron, influences a compass needle, and acts in every way like a permanent magnet.

In fact, FIGURE 29.20 shows that a flat permanent magnet and a current loop generate the same magnetic field—the field of a magnetic dipole. For both, you can identify the north pole as the face or end from which the magnetic field emerges. The magnetic fields of both point into the south pole.

FIGURE 29.20 A current loop has magnetic poles and generates the same magnetic field—a dipole field—as a flat permanent magnet.

One of the goals of this chapter is to show that magnetic forces exerted by currents and magnetic forces exerted by permanent magnets are just two different aspects of a single magnetism. This connection between permanent magnets and current loops will turn out to be a big piece of the puzzle.