Superconductivity

When certain materials are cooled below a critical temperature: T < T_c they can enter a superconducting state. In the superconducting state, electrical resistance to steady current becomes zero under suitable conditions. This can allow persistent currents.

A superconductor expels magnetic flux from its interior when it enters the superconducting state under appropriate conditions. This is called the: **Meissner effect**

Superconductivity can disappear if limits are exceeded, including: critical temperature; critical magnetic field; * critical current/current density.

Superconductors can be used in technologies requiring strong electromagnets and highly efficient current flow.

Superconductivity shows that matter at low temperature can exhibit collective quantum behaviour that cannot be explained by a simple classical ideal-gas model.

Condition: **T < T_c for superconducting transition when other critical conditions are also satisfied. Electrical resistance: R = 0** for ideal DC superconducting behaviour under superconducting conditions.