If the angle of dip at places $$A$$ and $$B$$ are $$30^{\circ}$$ and $$45^{\circ}$$ respectively, then the ratio of horizontal component of earth's magnetic field at $$A$$ to that at $$B$$ will be $$\left[\sin 45^{\circ}=\cos 45^{\circ}=\frac{1}{\sqrt{2}}, \sin \frac{\pi}{6}=\frac{1}{2}, \cos \frac{\pi}{6}=\frac{\sqrt{3}}{2}\right]$$

A thin light weight rod of diamagnetic substance such as silver is suspended in uniform external magnetic field. It will align itself with its length

Two identical bar magnets each of magnetic moment $$M$$, separated by some distance are kept perpendicular to each other. The magnetic induction at a point at the same distance $$d$$ from the centre of magnets, is ($$\mu_0=$$ permeability of free space)

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 $$3 \mathrm{~cm}^2$$. The magnetic permeability of the rod in $$\frac{\mathrm{Wb}}{\mathrm{A}-\mathrm{m}}$$ is