The magnetic susceptibility of a paramagnetic substance at $-123^{\circ} C$ is $0.0060$. What will be its value at $-173^{\circ} C$?

Give the unit and dimensional formula of magnetisation.

If $\mu_0$ is the permeability of vacuum and $\chi_m$ is the magnetic susceptibility,then the permeability of the material $\mu$ is . . . . . . .

The susceptibility of $Al$ is $2 \times 10^{-5}$. The percent increase in the magnetic field when the space within a current-carrying toroid is filled with $Al$ is:

$A$ solenoid has a core of a material with relative permeability $400$. The windings of the solenoid are insulated from the core and carry a current of $2 \; A$. If the number of turns is $1000$ per metre,calculate $(a) \; H$,$(b) \; M$,$(c) \; B$ and $(d)$ the magnetising current $I_m$.

$A$ solenoid of $500$ turns $/ m$ is carrying a current of $3 \ A$. Its core is made of iron which has a relative permeability of $5001$. The magnitude of magnetization is: