You Asked:

What is the meaning of super conductivity? — Aym, Daraa, Syrian Arab Republic

Marshall Brain Answers:

When scientists say that something is a superconductor, they mean that the material offers no resistance to electrical current.

Any normal conductor, like copper or aluminum at normal temperatures, offers some amount of resistance to current. For example, power lines made of copper or aluminum do conduct electricity very well, but there is always some small amount of resistance. Over many miles of wire, this resistance adds up. Roughly six percent or so of the power generated in the U.S. is lost to this resistance [ref]. The electricity turns into heat in the wires. So if we could make the electric transmission lines out of superconductors, much of this wasted electricity could be recovered.

If you cool a metal like tin down to liquid helium temperatures (just a 3.2 degrees K above absolute zero), it will become a superconductor. But liquid helium is expensive and hard top work with. Over the last 20 years, scientists have been creating new alloys that turn into superconductors at higher higher and higher temperatures (like those of liquid nitrogen). There’s even been news recently of new superconducting alloys working at normal freezer temperatures.

Besides having the ability to carry current without resistance, superconductors also have some interesting magnetic properties that make them useful for magnetic levitation. See this video for details: