The most exotic diamagnetic materials are super conductors. They exhibit perfect diamagnetism and perfect conductivity. The values of magnetic susceptibility \( (\chi) \) and relative permeability of such materials have values
Answer & explanation
Correct answer: option 2
The correct answer is Option (2) → \( \chi = -1,\;\;\mu_r = 0 \)
A superconductor shows perfect diamagnetism (the Meissner effect): it expels the magnetic field completely, so \( B = 0 \) inside it. Since \( B = \mu_0\mu_r H \), this means
\( \displaystyle \mu_r = 0 \)
The susceptibility and the relative permeability are related by
\( \displaystyle \mu_r = 1 + \chi \;\Rightarrow\; \chi = \mu_r - 1 = 0 - 1 = -1 \)
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 \( \mu_r = 0 \).”