of other telephones on the same (party) line. Future possibilities The development of modern rare-earth magnets makes the simple magneto alternator a more practical proposition as a power generator, as these permit a greatly increased field strength. As the magnets are compact and of light weight, they generally form the rotor, so the output windings can be placed on the stator, avoiding the need for brushgear. Guided missiles By the late 1980s, developments in magnetic materials such as samarium–cobalt, an early rare-earth type, let permanent magnet alternators be used in applications that require an extremely robust generator. In guided missiles, such generators can replace a flux switching alternator. These must operate at high speeds, directly coupled to a turbine. Both types share the advantage of the output coils being part of the stator, thus avoiding the need for brushgear. See also Electromagnetism Faraday's law of induction Notes References Electrical generators