The small magnets each of magnetic moment $10 \,A-m^2$ are placed end-on position $0.1\,m$  apart from their centres. The force acting between them is….$N$

A bar magnet of magnetic moment $M$ is cut into two parts of equal length. The magnetic moment of each part will be ……… $M$

Show the magnetic field of bar magnet in a panoramic way.

Figure shows a small magnetised needle $P$ placed at a point $O$. The arrow shows the direction of its magnetic moment. The other arrows show different positions (and orientations of the magnetic moment) of another identical magnetised needle $Q$.

$(a)$ In which configuration the system is not in equilibrium?

$(b)$ In which configuration is the system in $(i)$ stable, and $(ii)$ unstable equilibrium?

$(c)$ Which configuration corresponds to the lowest potential energy among all the configurations shown?

Write the equation of magnetic field on the axis of current carrying finite solenoid.