Two identical bar magnets with a length $10 \,cm $ and weight $50 \,gm$-weight are arranged freely with their like poles facing in a inverted vertical glass tube. The upper magnet hangs in the air above the lower one so that the distance between the nearest pole of the magnet is $3\,mm.$ Pole strength of the poles of each magnet will be.......$ amp × m$

A charged particle (charge $q$) is moving in a circle of radius $R$ with uniform speed $v.$ The associated magnetic moment $\mu $ is given by

The magnetic field due to a short magnet at a point on its axis at distance $X \,cm $ from the middle point of the magnet is $200 $ $Gauss$. The magnetic field at a point on the neutral axis at a distance $ X \,cm$  from the middle of the magnet is.....$Gauss$

The magnetic moment of the arrangement shown in the figure is ............. $M$

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?

The magnetic lines of force inside a bar magnet