A material which offers no resistance to the flow of electricity, when cooled below a certain temperature, called critical temperature (TC) is called a superconductor. Critical temperature is the characteristic of a particular material at which it attains the superconductivity.
(i) In natural metallic conductors, energy of electrons is gradually dissipated in the form of heat while conducting the electric current and thus the current flows down, but in case of superconductors, any current started will continue to flow until and unless it is stopped as it does not possess any friction like effect and there is nothing to slow down its flow.
(ii) Superconductors remain magnetic as long as the current is allowed to flow through in it.
(iii) The value of critical temperature (Tc) various from one superconductor to the other and this range generally from 4.1K to 125K. This change from normal conductivity to superconductivity is very abrupt.
Empirical Rules for super Conductivity
1- Only a few metals show superconductivity (Hg at 4.2K)
2- Ferromagnetic and antiferromagnetic (MnO) species don’t show this (FeO) phenomenon.
Author – Meena Soni