The permanent magnet is made from which one of the following substances?

Explain quantitatively the order of magnitude difference between the diamagnetic susceptibility of ${N_2} \left( { \sim 5 \times {{10}^{ - 9}}} \right)$ (at $STP$) and ${Cu} \left( { \sim {{10}^{ - 5}}} \right)$.

What is a paramagnetic substance? If a small bar of a paramagnetic substance is placed in a non-uniform magnetic field,in which direction does it move?

In a permanent magnet at room temperature,

$A$ diamagnetic material in a magnetic field moves:

$A$ long solenoid has $1000$ turns per metre and carries a current of $1 \, A$. It has a soft iron core of $\mu_r = 1000$. The core is heated beyond the Curie temperature,$T_C$.