$A$ wire of magnetic moment $M$ is bent to form a circular arc which subtends an angle $90^o$ at the center. Then,its new magnetic moment is:

Each atom of an iron bar $(5 \, cm \times 1 \, cm \times 1 \, cm)$ has a magnetic moment of $1.8 \times 10^{-23} \, A \cdot m^2$. Given that the density of iron is $7.78 \times 10^3 \, kg/m^3$,the atomic weight is $56 \, g/mol$,and Avogadro's number is $6.02 \times 10^{23} \, mol^{-1}$,calculate the magnetic moment of the bar in the state of magnetic saturation in $A \cdot m^2$.

$A$ bar magnet with a magnetic moment of $3.0 \, A \cdot m^2$ is placed in a magnetic field of $2 \times 10^{-5} \, T$. If the force acting on each pole is $6 \times 10^{-4} \, N$,what is the length of the magnet in $m$?

$A$ magnetized wire of magnetic moment $M$ and length $L$ is bent into an arc of a circle subtending an angle of $60^o$ at the center. The new magnetic moment is:

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

The incorrect statement regarding the lines of force of the magnetic field $B$ is: