DIPOLES AND MONOPOLES

You might at first think that the magnetic field around a current-carrying wire is caused by a monopole or that there aren’t any poles at all because the concentric circles apparently don’t originate or terminate anywhere. However, think of any geometric plane containing the wire. A magnetic dipole, or pair of opposite magnetic poles, is formed by the lines of flux going halfway around on either side. There in effect are two such “magnets” stuck together. The north poles and the south poles are thus not points but rather faces of the plane backed right up against each other.
The lines of flux in the vicinity of a magnetic dipole always connect the two poles. Some flux lines are straight in a local sense, but in a larger sense they are always curves. The greatest magnetic field strength around a bar magnet is near the poles, where the flux lines converge. Around a currentcarrying wire, the greatest field strength is near the wire.