The phenomenon of perfect diamagnetism in superconductors is called

The correct answer is Option (2) → Meissner Effect

A superconductor below its critical temperature expels the magnetic field completely from its interior: B = 0 inside, which corresponds to a susceptibility \( \chi = -1 \). This is perfect diamagnetism, and the expulsion of the field is called the Meissner effect.

NCERT (2026-27):
Diamagnetism – “… The most exotic diamagnetic materials are superconductors. These are metals, cooled to very low temperatures which exhibits both perfect conductivity and perfect diamagnetism. Here the field lines are completely expelled! \( \chi = -1 \) and \( \mu_r = 0 \). … The phenomenon of perfect diamagnetism in superconductors is called the Meissner effect, after the name of its discoverer.”