Magnetic levitation

Magnetic levitation suspends an object without mechanical contact by balancing its weight with magnetic forces. It can use attraction, repulsion, or controlled combinations of both.

Earnshaw's theorem: A theorem showing that static electric or magnetic fields alone cannot create stable equilibrium for a free point charge or dipole. It explains why simple static arrangements of ordinary magnets cannot stably levitate an object in every direction.
Maglev train: A train that uses magnetic forces to lift and guide its vehicles above a track. It is the best-known transport application of magnetic levitation.
Lorentz force: The force exerted on electric charges and currents by electric and magnetic fields. Currents in coils and conductors experience the forces that generate lift and guidance.
Acoustic levitation: The suspension of objects by acoustic radiation forces generated by sound waves. It suspends objects without magnetic fields, often using standing sound waves.
Electromagnetic suspension: A levitation method that uses electromagnets and feedback control to maintain a gap between an object and a track. Sensors and changing coil currents overcome the instability of attractive suspension.
Magnetic levitation melting: A materials-processing technique that melts a sample while magnetic forces suspend it without a container. Contact-free support prevents crucible contamination during high-temperature processing.
Magnetic field: A vector field that describes magnetic influence on moving charges, currents, and magnetic materials. Its strength and spatial variation set the forces available for suspension.
Optical levitation: The suspension or manipulation of small objects using forces from light. It replaces magnetic forces with light, especially for microscopic particles.
Electrodynamic suspension: A levitation method in which motion induces currents that create magnetic forces opposing the motion. Unlike feedback-controlled attraction, it typically needs motion to generate lift.
Flywheel energy storage: An energy-storage system that stores energy as the rotational kinetic energy of a rapidly spinning rotor. Magnetic bearings can reduce friction and wear in high-speed flywheels.

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