The field due to a magnet at a distance $ R$ from the centre of the magnet is proportional to
${R^2}$
${R^3}$
$1/{R^2}$
$1/{R^3}$
The magnetic field of earth at the equator is approximately $4 \times 10^{-5}\, T$ . The radius of earth is $6.4 \times 10^6\, m$. Then the dipole moment of the earth will be nearly of the order of
The mid points of two small magnetic dipoles of length $d$ in end-on positions, are separated by a distance $x, (x > > d)$. The force between them is proportional to $x^{-n}$ where $n$ is
Magnetic lines of force due to a bar magnet do not intersect because
A magnet is placed in iron powder and then taken out, then maximum iron powder is at
Two magnets $A$ and $B $ are identical and these are arranged as shown in the figure. Their length is negligible in comparison to the separation between them. A magnetic needle is placed between the magnets at point $P$ which gets deflected through an angle $\theta $ under the influence of magnets. The ratio of distance ${d_1}$ and ${d_2}$ will be