Superconductivity allows some materials to conduct electricity with zero resistance below a critical temperature.
A superconducting material can carry electric current without the ordinary resistive energy loss found in metals. The transition occurs below a material-specific critical temperature, often under additional limits involving magnetic field and current. Superconductors also exhibit the Meissner effect, expelling magnetic flux from their interior under suitable conditions.
Heike Kamerlingh Onnes discovered superconductivity in 1911 while studying mercury cooled with liquid helium. He observed that mercury’s resistance abruptly vanished near 4.2 kelvin. Later theories explained conventional superconductivity through paired electrons and interactions with the crystal lattice.
Zero resistance does not mean superconductors work under every condition. Excessive temperature, magnetic field, or current can destroy the superconducting state. Applications include MRI magnets, particle accelerators, sensitive detectors, and experimental power systems.