Choose the correct statement.

$A$ long magnetic needle of length $2L$,magnetic moment $M$,and pole strength $m$ is broken into two equal pieces at the middle. The magnetic moment and pole strength of each piece will be

Define the pole strength of a magnet and write its $SI$ unit.

Two identical thin bar magnets are placed mutually at right angles such that the north pole of one touches the south pole of the other. The length of each bar magnet is $\ell$. The magnitude of the resultant magnetic moment of the system is $[m = \text{pole strength of the magnet}]$.

$A$ metal wire of length $l$ has a magnetic moment $M$. What is the new magnetic moment if it is bent into an $L$-shape?

Verify Ampere's law for the magnetic field of a point dipole with dipole moment $\vec{M} = M\hat{k}$. Take $C$ as the closed curve running clockwise along the $z$-axis from $z = a > 0$ to $z = R$,then along the circular arc of radius $R$ to the $x$-axis,then along the $x$-axis to $x = a$,and finally along the circular arc of radius $a$ back to the $z$-axis.