Superjohtuvuus

Superjohtuvuus is a quantum mechanical phenomenon observed in certain materials at very low temperatures. When cooled below a critical temperature, these materials lose all electrical resistance, allowing electric current to flow indefinitely without any energy loss. This state is known as superconductivity.

The discovery of superconductivity dates back to 1911 when Dutch physicist Heike Kamerlingh Onnes observed it in mercury. Further research revealed that superconductivity is not limited to mercury and can occur in various metals, alloys, and ceramic compounds. The critical temperature at which superconductivity appears varies significantly between different materials.

A key characteristic of superconductors is their ability to expel magnetic fields, a phenomenon called the Meissner effect. When a superconductor is placed in a magnetic field below its critical temperature, it actively pushes the magnetic field lines out of its interior. This property has led to numerous practical applications.

Applications of superconductivity include powerful electromagnets used in MRI scanners, particle accelerators, and magnetic levitation (maglev) trains. Researchers are also exploring its potential in energy transmission, quantum computing, and highly sensitive magnetic field detectors. Despite its promising applications, the requirement of extremely low temperatures for most superconductors limits their widespread adoption. Efforts are ongoing to discover or engineer materials that exhibit superconductivity at higher, more accessible temperatures.