Development of Magneto-Archimedes Levitation

A maglev train will be the first thing come up to a man’s imagine when he hears “magnetic levitation”. For it is well known that magnets will be repel each other when their same poles getting close. However, it is impossible to use a single magnet to levitate another magnet. This phenomenon was firstly proved by Earnshaw in 1842 through theoretical derivation. The Earnshaw theorem pointed out that the point particle set cannot be stably maintained in a stable static mechanical equilibrium structure consisting only of electrostatic interaction of charge. Therefore, to obtain statically stable levitation between magnets, additional constraints need to be added. Usually, two or more sets of magnet pairs are used in one system, such as in some kind of maglev trains. Due to the magnetic flux intensity of an electromagnet can be directly adjusted by changing the current through the coils, precise control method can remain a dynamic stabilization between two magnets.