When a piece of a ferromagnetic substance is placed in a uniform magnetic field,the flux density inside it is four times the flux density away from the piece. The magnetic permeability of the material is

$ \chi_{1} $ and $ \chi_{2} $ are the magnetic susceptibilities of a paramagnetic material at temperatures $ T_{1} \ K $ and $ T_{2} \ K $ respectively. Then:

At a temperature of $30\,^oC$,the susceptibility of a ferromagnetic material is found to be $\chi$. Its susceptibility at $333\,^oC$ is....$\chi$.

$A$ solenoid has a core of material with relative permeability $501$. The windings of the solenoid are insulated from the core and carry a current of $2.5 \ A$. If the number of turns is $900$ per metre,the magnetization in $A \ m^{-1}$ is:

If the relative permeability of iron is $5500$, then its magnetic susceptibility is:

An iron rod is placed parallel to a magnetic field intensity of $1000 \text{ A/m}$. The magnetic flux through the rod is $3 \times 10^{-4} \text{ Wb}$ and its cross-sectional area is $1.5 \text{ cm}^2$. The magnetic permeability of the rod in $\text{Wb/(A} \cdot \text{m)}$ is: