Magnetism

The totality of all physical phenomena related with the presence or generation of magnetic fields (cf. also Magnetic field). The first observations of magnetic phenomena date from the remote Antiquity. The mysterious capacity of the magnet to attract iron objects is mentioned in Ancient chronicles and legends from Asia, India, China, Central America, Greece, and Rome. Oriental chronicles from the second millennium B.C. describe some first practical applications of magnetic phenomena. Ancient Hindus used the magnet for extracting iron ferrules of arrows from the bodies of wounded warriors and Chinese chronicles narrate about a magic magnetic gate through which an armed person could not pass as well as about compasses.

The scientific explanation of magnetic properties of substances experienced a long evolution, from a magnetic liquid to a representation of molecules as magnetic dipoles and finally to the modern point of view, which explains magnetic properties of physical bodies via the revolution of electrons around the nuclei of atoms and uses the notion of electron spin. This present-day knowledge makes the theory of magnetism an integral part of electromagnetic theory, the mathematical basis of which are the Maxwell equations describing the interaction of electric and magnetic fields in physical media. See also Electromagnetism.