What is Superconductivity ?
Superconductivity is a phenomenon in which Superconducting materials show distinct electrical and magnetic properties than Conductors. Superconductors Show complete disappearance of the Resistance below a certain Temperature i.e Critical Temperature (Tc). It means electric currents can flow in these Superconducting Circuits for several years without any significant decay in magnitude.
Superconductors Show perfect Diamagnetism and they totally expulse magnetic flux. Also, they have negative Susceptibility and can acquire a polarization opposite to the applied magnetic field. Meissner effect is also one property of a Superconductor in which it excludes all the applied Magnetic field.
The Experiments behind the discovery of Superconductivity is quite interesting. A Dutch scientist Kamerlingh Onnes in 1911 was testing dependencies of Resistance on the temperature of Conducting material. He thought there would be a steady decrease in electrical Resistance if I will continuously decrease the temperature of the conducting material. He was using very pure mercury wire and measured its resistance as he steadily lowered the temperature. Much to his surprise, there was no electrical Resistance at 4.2 Kelvin which means at that temperature mercury was an extremely good conductor of electricity i.e Superconductor.
Types of Superconductor
27 metals from the periodic table show Superconductivity below Critical Temperature these are called Type I Superconductors while Superconductors made form alloys of different elements are classified as Type II Superconductors. Type II Superconductors are much harder than elementary Superconductors and they also have much higher Critical Magnetic Fields.
In Superconductors, electrical Resistance drops to zero after Critical Temperature because Resistance is caused by the collisions of moving electrons in the material and electron loose energy to drop in the lower energy level but in Superconductors, all the electron pairs lay in the ground state and can not lose further energy.
In 1986 Johannes Georg Bednorz and Karl Alex Muller two Scientists Discovered high-temperature Superconductivity in metal oxides. They were also awarded the Novel Prize for Physics in 1987 for this Work. Currently, many Organisations in the world are working to discover Other high-temperature superconductors because is much easier and cheaper to implement it.
Uses of Superconductor
So far the development in the field of Superconductors is Vital but in the Upcoming future Superconductors will revolutionize electrical and magnetic Technology. Superconductors have a significant role in medical Sciences. Improvement in MRI Technology with Superconductors & Use in Large hadron collider or Particle accelerator is significant. Japan is working on Maglev Trains which is still not Operational but will soon it will be possible to Take a ride of it in the upcoming decade.