magnetism

Definition: Phenomena associated with magnetic fields. When an electric current flows, a magnetic field is produced. The orbital motion and spin of atomic electrons are equivalent to tiny current loops - atoms create magnetic fields around them when their orbital electrons have a net magnetic moment - the sum of the magnetic moments of the orbital motions and the spins of all the electrons. The macroscopic magnetic properties of a substance arise from the magnetic moments of its component atoms and molecules. Different materials have different characteristics in an applied magnetic field; there are four main types: diamagnetism, paramagnetism, ferromagnetism and antiferromagnetism