Magneticlevitation

Magneticlevitation is the suspension of an object in a magnetic field against gravity without physical contact. In practical contexts it is achieved through carefully arranged magnetic forces and, in many cases, active control to balance weight.

Several approaches exist. Electromagnetic suspension uses sensors and feedback to drive electromagnets that counteract gravity. Electrodynamic suspension relies on induced currents in conductors or superconductors as magnets move, producing repulsion by Lenz's law. Diamagnetic levitation exploits materials that weakly oppose magnetic fields, enabling stable lift with strong magnets or superconductors. Superconducting levitation uses the Meissner effect to expel magnetic fields and support levitation at cryogenic temperatures. Permanent magnet levitation can be unstable in static arrangements, requiring active control, diamagnetic materials, or superconductors for stability.

The idea dates to early theoretical work on magnetic fields, with practical demonstrations in the 20th century and rapid development in recent decades. Modern maglev systems use EMS or EDS in passenger trains such as Shanghai’s maglev and other high-speed lines.

Applications include high-speed transportation and contactless bearings or flywheels. Benefits are reduced friction and wear, while challenges involve energy use for active stabilization, cooling for superconductors, and high system costs.