$A$ magnet is placed in iron powder and then taken out,then maximum iron powder is at

In the following figures,the lines of magnetic induction due to a magnet $SN$ are given by:

$A$ magnetic needle is kept in a non-uniform magnetic field. It experiences

The average dipole moment of $Fe$ atoms is $1.8 \times 10^{-23} \ A-m^2$. The magnetic moment of an iron rod of length $10 \ cm$ and diameter $1 \ cm$ is........$A-m^2$: (density and atomic weight of $Fe$ are $7.87 \ g/cm^3$ and $55.87$ respectively).

Two short magnets of equal dipole moments $M$ are fastened perpendicularly at their centres. The magnitude of the magnetic field at a distance $d$ from the centre on the bisector of the right angle is ($\mu_0 =$ Permeability of free space).

Three identical bar magnets are riveted together at the centre in the same plane as shown in the figure. This system is placed at rest in a slowly varying magnetic field. It is found that the system of magnets does not show any motion. The north-south poles of one magnet are shown in the figure. Determine the poles of the remaining two.