Define Superconductivity.

Hint: Superconductivity is a phenomenon in which certain metals show a very remarkable behavior. When they are cooled, their electrical resistance decreases in an unusual way but on reaching a temperature a few degrees above the absolute zero they suddenly lose all trace of electrical resistance. The substances which show these kinds of phenomena are called superconductors.

Complete step by step solution:
Superconductivity: It is a special kind of phenomenon in which certain substances (conductor of electricity) offer zero resistance when it allows to cool up to some temperature level called (Tc) critical temperature. The substances which show the phenomenon of superconductivity are called superconductors.
As we all know that the resistance of a normal conductor decreases in decreasing the temperature while it must have some finite value even at significantly low temperature which is due to impurities present in it while in case of superconductor resistance will suddenly drop to zero at the critical temperature. The superconductors are mostly metal or alloy of metal.



The superconductor shows perfect diamagnetism at the critical temperature means it strongly repels the applied external magnetic field. The phenomenon of superconductivity occurs at very low temperatures like for mercury its critical temperature is around 4.2 K which is tough and costly. So to get a special class of superconductors which can show the phenomenon of superconductivity at high-temperature research is dedicatedly going on.

Note:
Now, these days superconductivity is one of the most fascinating areas of research. During the transition of a superconductor from its normal state to a superconductive state is called phase transition which has its own importance in the field of physics.
Research in the area of developing high-temperature superconductors has given many of them like- YBCO, BSCCO, etc. In order to understand the phenomenon of superconductivity we just have to read about the basic article on it not to go much deeper into that.