Coilandmagnet

Coilandmagnet is a term used to describe the basic interaction between an electric coil and a magnetic field, a core element in many electrical machines and devices. The coil, typically made of conductive wire, can be energized to produce a magnetic field, or can sense changes in magnetic flux through a coil of wire.

In operation, current through a coil generates a magnetic field that interacts with a magnet's field, while changes in magnetic flux passing through a coil induce an electromotive force (EMF) in accordance with Faraday's law. The resulting induced current or force can drive motion or harvest electrical energy. Lenz's law describes the direction of the induced effects, opposing the change that produced them.

Coil and magnet systems can be arranged in various configurations. A stationary coil with a moving magnet is common in generators and linear actuators; or a moving coil with a fixed magnet is used in some loudspeakers and sensors. Both permanent magnets and electromagnets may serve as the magnetic source, and the geometry determines whether the device functions as motor, generator, transformer, or actuator.

Applications span motors, generators, and power conversion devices, as well as loudspeakers, relays, and magnetic sensors. In transformers, coils are magnetically coupled through a core to transfer energy between circuits.

Historically, the concepts behind coil and magnet interactions were formalized in the 19th century through Faraday's experiments and subsequent developments in electromagnetism. See also electromechanical energy conversion and electromagnetic induction.