When a piece of a magnetic 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

$A$ permanent magnet in the shape of a thin cylinder of length $10$ $cm$ has magnetization $M = 10^6$ $A/m$. Calculate the magnetization current $I_M$.

$A$ magnetizing field of $2 \times 10^3 \, A/m$ produces a magnetic flux density of $8 \pi \, T$ in an iron rod. The relative permeability of the rod will be -

The relation between the magnetic susceptibility $\chi$ and the relative magnetic permeability $\mu_r$ is:

The unit for molar susceptibility is

An iron rod of volume $10^{-3} \ m^3$ and relative permeability $1000$ is placed as a core in a solenoid with $10 \ turns/cm$. If a current of $0.5 \ A$ is passed through the solenoid,then the magnetic moment of the rod will be $........... \ Am^2$.