An iron rod is placed parallel to magnetic field of intensity $2000 \mathrm{A} \mathrm{m}$. The magnetic flux through the rod is $6\times {10}^{-4}\mathrm{ Wb}$ and its cross-sectional area is $\mathrm{3 }\mathrm{c}{\mathrm{m}}^2$. The magnetic permeability of the rod in $\mathrm{W}\mathrm{b} {\mathrm{A}}^{-1}{\mathrm{m}}^{-1}$ is

Consider the regular array of vertical identical current-carrying wires (with the direction of current flow as indicated in the figure below) protruding through a horizontal table. If we scatter some diamagnetic particles on the table, they are likely to accumulate-

Two magnetic dipoles $\mathrm{X}$ and $\mathrm{Y}$ are placed at a separation $\mathrm{d}$ , with their axes perpendicular to each other. The dipole moment of $\mathrm{Y}$ is twice that of $\mathrm{X}$ . A particle of charge $\mathrm{q}$ is passing through their mid-point $\mathrm{P}$ , at angle $\mathrm{\theta }={45}^{\mathrm{o}}$ with the horizontal line, as shown in figure. What would be the magnitude of force on the particle at that instant? ( $\mathrm{d}$ is much larger than the dimension of the dipole)

The shape of the path of free electron in a metal is _____: