The magnetic potential energy, when a magnetic bar of magnetic moment $$\vec{m}$$ is placed perpendicular to the magnetic field $$\vec{B}$$ is
The incorrect relation for a diamagnetic material (all the symbols carry their usual meaning and $$\varepsilon$$ is a small positive number) is
The magnetic moment and moment of inertia of a magnetic needle as shown are, respectively, $$1.0 \times 10^{-2} \mathrm{~A} \mathrm{~m}^2$$ and $$\frac{10^{-6}}{\pi^2} \mathrm{~kg} \mathrm{~m}^2$$. If it completes 10 oscillations in $$10 \mathrm{~s}$$, the magnitude of the magnetic field is
The magnetic moment of an iron bar is $$M$$. It is now bent in such a way that it forms an arc section of a circle subtending an angle of $$60^{\circ}$$ at the centre. The magnetic moment of this arc section is