superconductivity
Sign in to savethumb|A high-temperature superconductor levitating above a magnet. A persistent electric current flows on the surface of the superconductor, acting to exclude the magnetic field of the magnet (Meissner effect). This current effectively forms an electromagnet that repels the magnet.
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Superconductivity is a special state of certain materials where electric current can flow indefinitely without any resistance, and the material actively pushes away magnetic fields—an effect called the Meissner effect. This matters because it enables remarkable applications like magnetic levitation, where a superconductor can float above a magnet due to the repulsive force created by the persistent current flowing across its surface.
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Article
23 sectionsContents
- History
- London constitutive equations
- Conventional theories (1950s)
- Niobium
- Josephson effect
- 2D materials
- Classification
- Response to a magnetic field
- Theory of operation
- Critical temperature
- Material
- Elementary properties
- Zero electrical DC resistance
- Phase transition
- Meissner effect
- London moment
- High-temperature superconductivity
- Applications
- Nobel Prizes
- See also
- References
- Further reading
- External links
thumb|A high-temperature superconductor levitating above a magnet. A persistent electric current flows on the surface of the superconductor, acting to exclude the magnetic field of the magnet (Meissner effect). This current effectively forms an electromagnet that repels the magnet.
Superconductivity is a set of physical properties observed in superconductors: materials where electrical resistance vanishes and magnetic fields are expelled from the material. Unlike an ordinary metallic conductor, whose resistance decreases gradually as its temperature is lowered, even down to near absolute zero, a superconductor has a characteristic critical temperature below which the resistance drops abruptly to zero. An electric current through a loop of superconducting wire can persist indefinitely with no power source.