Magnete

Magnete is a term used in several languages for magnets; it refers to objects that produce a magnetic field, exerting forces on other magnets and on certain materials, and often attracting ferromagnetic substances such as iron. Magnets can be natural, like lodestone, or manufactured for specific properties and shapes.

There are two broad classes: permanent magnets, which retain a magnetic moment without continuous power, and electromagnets, which generate a magnetic field when electric current flows through a coil around a metal core. Permanent magnets are made from materials such as ferrites, alnico, and rare-earth alloys (neodymium-iron-boron NdFeB and samarium-cobalt SmCo). Electromagnets consist of coils of wire wound around a ferromagnetic core.

In ferromagnetic materials, microscopic regions called magnetic domains align to create a net magnetic moment. External magnetic fields can reorient domains; heating can disrupt alignment. The Curie temperature marks where magnetic order is lost. Magnets have properties such as remanence and coercivity that describe their behavior.

Applications include electric motors and generators, transformers, magnetic storage devices, loudspeakers, magnetic separation in mining, lifting magnets, and medical imaging devices such as MRI.

Historically, lodestones were used in antiquity. The scientific study began with William Gilbert in the 16th century, who described earth's magnetism. The word magnet derives from Greek magnētis lithos, meaning "magnetic stone."