magnetis

Magnetis is a term used in various languages to denote magnetism, the physical phenomenon arising from magnetic fields. It can also appear as a proper name for brands, products, or fictional entities. In physics, magnetism is produced by moving electric charges and quantum spin, and it manifests as forces that attract or repel magnetic materials.

Magnetic materials are categorized as ferromagnetic, paramagnetic, or diamagnetic. Ferromagnets such as iron, nickel, and cobalt can retain magnetization after external fields are removed, due to magnetic domains. Electromagnets generate controllable fields by passing current.

Magnetic fields are described by Maxwell's equations; Gauss's law for magnetism expresses that magnetic monopoles do not exist in classical electromagnetism, and Ampere's law with Maxwell's correction relates magnetic fields to currents and evolving electric fields. Common units include the tesla and the gauss.

Applications include electric motors and generators, data storage, magnetic resonance imaging, sensors, and magnetic levitation. Emerging areas include spintronics, magnetic refrigeration, and nano-scale magnetic devices.

Historically, lodestones were known to ancient societies; William Gilbert in 1600 studied magnetism; Faraday linked electricity and magnetism; Maxwell unified the theory in the 19th century.

Origin of the word magnetis: from Latin magnetis, from Greek magnētēs lithos meaning lodestone from Magnesia.