MAGLEV

Magnetic Levitation

Magnetic Levitation is when an object is suspended in midair with no means other than electromagnetism. It can be used for entertainment, but is also very useful at reducing friction or counteracting gravitational forces. Magnetic levitation, or maglev, consists of two primary forces: the lifting force, keeping the object up in the air, and stability, which ensures the object does not slide out of the magnetic field. 

A levitating top, spinning on top of a magnetic field.

One example of an everyday use of maglev is maglev trains. These trains, instead of having the wheels physically on the tracks, have electromagnets in the rails as well as in the part of the train "connected" to the tracks. This eliminates the friction that would create an inefficient use of energy. When activated, the electromagnets send current in one direction, propelling the train forwards on the track, until it needs to slow down, in which case the magnets create a backwards flow of current to slow the forwards progress of the train. 

A maglev train

https://en.wikipedia.org/wiki/Magnetic_levitation

https://www.youtube.com/watch?v=SKQdJZib2vs