Superconducter

A small cylindrical magnet floats above a high temperature superconductor. The vapor is from boiling liquid nitrogen, which keeps the superconductor in a zero-resistance state. As the magnet is lowered toward the superconductor, it induces an electric current, which creates an opposing magnetic field in accordance with Ampere’s law. Because the superconductor has no electrical resistance, this induced current continues to flow, keeping the magnet suspended indefinitely.

A superconductor is a material that can conduct electricity or transport electrons from one atom to another with no resistance. This means no heat, sound or any other form of energy would be released from the material when it has reached "critical temperature" (T_c), or the temperature at which the material becomes superconductive. Unfortunately, most materials must be in an extremely low energy state (very cold) in order to become superconductive. Research is underway to develop compounds that become superconductive at higher temperatures. Currently, an excessive amount of energy must be used in the cooling process making superconductors inefficient and uneconomical.

An electrical current in a wire creates a magnetic field around a wire. The strength of the magnetic field increases as the current in the wire increases. Because superconductors are able to carry large currents without loss of energy, they are well suited for making strong electromagnets. When a superconductor is cooled below its transition temperature (T) and a magnetic field is increased around it ,the magnetic field remains around the superconductor. Physicists use the capital letter H as the symbol for Magnetic Field. If the magnetic field is increased to a given point the superconductor will go to the normal resistive state.