Diamagnetism is a form of magnetism that is only exhibited by a substance in the presence of an externally applied magnetic field. It is the result of changes in the orbital motion of electrons due to the application of an externally applied magnetic field. Applying a magnetic field causes a momentary electromotive force (a consequence of Faraday's law), which modifies the electronic orbitals of atoms/molecules in a substance in such a way, that the orbitals produce an induced magnetic field, which opposes the applied field (a consequence of Lenz's law). However, the induced magnetic moment is very small in most everyday materials.
Diamagnets are repelled by magnetic fields. However, since diamagnetism is such a weak property its effects are not observable in every-day life.
However, in Magnetic Resonance Imaging for example barium sulfate suspensions lead with its weak negative magnetic susceptibility to a decrease in signal.

See also magnetism, ferromagnetism, paramagnetism, and superparamagnetism.

A type of magnet that utilizes coils of wire, typically wound on an iron core, so that as current flows through the coil it becomes magnetized. The direction of the magnetic field is parallel to the long axis of the coil. Whole body electromagnets, used in medical imaging (also called resistive) are limited to their field strength, because the weight becomes prohibitively large at high field MRI. The magnetic field shuts down, if the current is switched of. Because this type of magnet generates heat, a good cooling system is essential.
For a stronger magnetic field, the wires must be manufactured of superconducting materials to reduce the power needed to produce the field.

See also Resistive Magnet, Superconducting Magnet and Uprightâ„¢ MRI

A substance, such as iron, that has a large positive magnetic susceptibility.

Magnet system employing both current-carrying coils and permanently magnetized material to generate the magnetic field.

The magnetic polarization of a material produced by a magnetic field (magnetic moment per unit volume).

See also Macroscopic Magnetization Vector.