What is the magnetic susceptibility of a medium if its relative permeability is $0.85$?

$A$ rod of ferromagnetic material with dimensions $10 \, cm \times 0.5 \, cm \times 0.2 \, cm$ is placed in a magnetic field of strength $0.5 \times 10^4 \, A/m$. As a result,a magnetic moment of $5 \, A \cdot m^2$ is produced in the rod. The value of the total magnetic induction will be (in $Tesla$):

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

An iron rod is placed parallel to a magnetic field of intensity $2000 \text{ A/m}$. The magnetic flux through the rod is $6 \times 10^{-4} \text{ Wb}$ and its cross-sectional area is $3 \text{ cm}^2$. The magnetic permeability of the rod in $\text{Wb/(A} \cdot \text{m)}$ 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 $I_M$.

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