What is a defining feature of superconductors?

Superconductors are characterized by their ability to conduct electricity without any resistance when cooled below a certain critical temperature. This phenomenon of zero electrical resistance means that once an electric current is established in a superconducting material, it can flow indefinitely without any loss of energy due to resistance. This property has significant implications for various applications, including magnetic levitation, energy storage systems, and advanced computing technologies.

The critical temperature is unique for each superconducting material; below this temperature, the material undergoes a transition that allows for the unhindered flow of electric charge. The presence of zero resistance also implies that magnetic field lines are expelled from the superconducting material, a phenomenon known as the Meissner effect.

Understanding this fundamental characteristic of superconductors helps to distinguish them from regular conductors and insulators. Regular conductors, for example, still exhibit some level of resistance, while insulators do not conduct electricity at all. Therefore, the defining feature of superconductors is indeed their zero resistance when cooled below the critical temperature.