Question

why when a circular superconductor cooled has magnetic filed?

Answer 1

Superconductors repel magneticfields due to the Meissner effect. Near the surface of the superconductor material, small currents flow (without any resistance) that make an opposite magnetic field that repels the field from the magnet.

Answer 2

the field of superconductivity, so it is important to understand the magnetic properties ...... If a perfect conductor is cooled below its critical temper- ...... tron is in a circular orbit of radius.