If the magnetic susceptibility of a substance is $0.6$,then the ratio of permeability of the substance and permeability of free space is

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

The magnetic susceptibility of a material of a rod is $499$. Permeability in vacuum is $4\pi \times 10^{-7} \text{ H/m}$. Absolute permeability of the material of the rod is $....\pi \times 10^{-4} \text{ H/m}$.

$A$ domain in ferromagnetic iron is in the form of a cube of side length $1\; \mu m$. Estimate the number of iron atoms in the domain and the maximum possible dipole moment and magnetisation of the domain. The molecular mass of iron is $55\; g/mol$ and its density is $7.9\; g/cm^3$. Assume that each iron atom has a dipole moment of $9.27 \times 10^{-24}\; A m^2$.

Explain the magnetic susceptibility $(\chi)$ of a material. From it,explain the relative magnetic permeability and magnetic permeability of the material. Obtain the relation between them.

The dimensions $[MLT^{-2}A^{-2}]$ belong to: