Superconductors

A superconductor is a material that can conduct electricity without resistance. However superconductors are not only infinitely good conductor but they are perfect diamagnets as well. A diamagnet replaces magnetic field and weakens it inside . A superconductor can completely weaken the magnetic fieldand repels it from within . This is known as Meissner Effect. Based upon this effect, Maglev trains (Magnetic Leviation Trains) are designed. The field lines run completely around the superconductor.The counterpart to diamagnets are para- and ferromagnets that amplify an external magnetic field.

Meissner Effect and Leviation of a Magnet by Superconductor