Supergeleider

A superconductor is a material that offers zero resistance to the flow of electrons with an efficient transfer of electrical energy and no heat loss.

In 1911, Heike Kamerlingh Onnes observed that resistance goes to zero when mercury is cooled below 4.2 Kelvin. This is known as the critical temperature for mercury, and the phenomenon is known as superconductivity.

When the temperature increases above the critical temperature, the resistance changes linearly with it.

Another aspect of a superconductor's magnetic behavior is observed when a homogeneous superconducting material is placed in an external uniform magnetic field.

When the temperature is greater than the critical temperature, the field inside the material is equal to the external uniform magnetic field. If it is lower than the critical temperature, the magnetic flux is expelled from the material, and the field inside it is zero. This phenomenon is known as the Meissner effect.

The superconductivity of a material below the critical temperature can be eliminated by applying the minimum magnitude of the magnetic field, known as the critical magnetic field.