How does a superconductor cooled in a magnetic field differ from a hypothetical, perfectly conducting material upon cooling?

Answer

The superconductor actively expels internal magnetic field lines (Meissner effect).

A hypothetical perfect conductor would trap flux inside. A true superconductor actively expels all internal magnetic field lines when cooled below $T_c$, a defining characteristic known as the Meissner effect.

How does a superconductor cooled in a magnetic field differ from a hypothetical, perfectly conducting material upon cooling?
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