|
In physics, there are two kinds of dipoles such as electric dipole and magnetic dipole. The simplest example of an electric dipole is a pair of electric charges of equal magnitude but opposite sign, separated by a small distance. A magnetic dipole is a closed circulation of electric current. A simple example of this is a single loop of wire with some constant current flowing through it.
Dipoles can be characterized by their dipole moment, which is a vector quantity. For a current loop, the magnetic dipole moment would point through the loop (according to the right hand rule), with a magnitude equal to the current in the loop times the area of the loop.
In addition to current loops, the electron is said to have a magnetic dipole moment as it generates a magnetic field, which 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.
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 and are labeled "north" and "south”. The dipole moment of the bar magnet is from its magnetic south to its magnetic north.
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.
Force on a Dipole in a Non-uniform Field:
When a material is placed within a magnetic field, the magnetic forces of the material's electrons will be affected. This effect is known as Faraday's Law of Magnetic Induction. However, materials can react quite differently to the presence of an external magnetic field. This reaction is dependent on a number of factors, such as the atomic and molecular structure of the material, and the net magnetic field associated with the atoms. Thus if we place a magnetic dipole in a non-uniform field it will experience a force and accordingly its alignment will depend upon the properties of the concerned material.
|
