The magnetic field of a sphere with a north magnetic pole at the top and a south magnetic pole at the bottom. By comparison,
has a south
magnetic pole near its north geographic pole and a north
magnetic pole near its south pole.
electromagnetism, there are two kinds of dipoles:
electric dipole is a separation of positive and negative charges. The simplest example of this is a pair of
electric charges of equal magnitude but opposite sign, separated by some (usually small) distance. A permanent electric dipole is called an
magnetic dipole is a closed circulation of
electric current. A simple example of this is a single loop of wire with some constant current through it.
Dipoles can be characterized by their dipole moment, a vector quantity. For the simple electric dipole given above, the
electric dipole moment points from the negative charge towards the positive charge, and has a magnitude equal to the strength of each charge times the separation between the charges. (To be precise: for the definition of the dipole moment, one should always consider the "dipole limit", where, for example, the distance of the generating charges should converge to 0 while simultaneously, the charge strength should diverge to infinity in such a way that the product remains a positive constant.)
For the current loop, the
magnetic dipole moment points through the loop (according to the
right hand grip rule), with a magnitude equal to the current in the loop times the area of the loop.
In addition to current loops, the
electron, among other
fundamental particles, has a magnetic dipole moment. That is because it generates a
magnetic field that is identical to that generated by a very small current loop. However, the electron's magnetic moment is not due to a current loop, but is instead an
intrinsic property of the electron.
 It is also possible that the electron has an electric dipole moment although it has not yet been observed (see
electron electric dipole moment for more information).
Contour plot of the
of a horizontally oriented electrical dipole of finite size. Strong colors indicate highest and lowest potential (where the opposing charges of the dipole are located).
A permanent magnet, such as a bar magnet, owes its magnetism to the intrinsic magnetic dipole moment of the electron. The two ends of a bar magnet are referred to as poles (not to be confused with
monopoles), and may be labeled "north" and "south". In terms of the Earth's magnetic field, they are respectively "north-seeking" and "south-seeking" poles: if the magnet were freely suspended in the Earth's magnetic field, the north-seeking pole would point towards the north and the south-seeking pole would point towards the south. The dipole moment of the bar magnet points from its magnetic
south to its magnetic
north pole. The north pole of a bar magnet in a
compass points north. However, that means that Earth's geomagnetic north pole is the south pole (south-seeking pole) of its dipole moment and vice versa.
The only known mechanisms for the creation of magnetic dipoles are by current loops or quantum-mechanical
spin since the existence of
magnetic monopoles has never been experimentally demonstrated.
The term comes from the
Greek δίς (dis), "twice"
 and πόλος (polos), "axis".