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

The magnetic susceptibility of a ferromagnetic substance 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 $I_M$.

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

The value of aluminium susceptibility is $2.2 \times 10^{-5}$. The percentage increase in the magnetic field if space within a current-carrying toroid is filled with aluminium is $\frac{x}{10^{4}}$. Then the value of $x$ is ...... .

What are the dimensions of $\chi$,the magnetic susceptibility? Consider an $H$-atom. Guess an expression for $\chi$,up to a constant,by constructing a quantity of dimensions of $\chi$ out of parameters of the atom: $e, m, v, R$ and $\mu_0$. Here,$m$ is the electronic mass,$v$ is electronic velocity,$R$ is Bohr radius. Estimate the number so obtained and compare with the value of $|\chi| \approx 10^{-5}$ for many solid materials.