If a bar magnet of pole strength $m$ and magnetic moment $M$ is cut equally 5 times parallel to its axis and…
If a bar magnet of pole strength $m$ and magnetic moment $M$ is cut equally 5 times parallel to its axis and again 3 times perpendicular to its axis, then the pole strength and magnetic moment of each piece are respectively
$\frac{m}{20}, \frac{M}{4}$
$\frac{m}{5}, \frac{M}{20}$
$\frac{m}{6}, \frac{M}{24}$
$\frac{m}{5}, \frac{M}{24}$
Solution
Given, pole strength $=m$
and magnetic moment $=M$
When it is cut 5 times parallel to its axis, pole strength, $m^{\prime}=\frac{m}{6}$
When it is cut 3 times perpendicular to its axis, then length $2 l^{\prime}=\frac{2 l}{4}$
$\therefore$ pole strength, $m^{\prime}=\frac{m}{6}$
and magnetic moment,
$M^{\prime}=\left(\frac{m}{6}\right)\left(\frac{2 l}{4}\right)=\frac{M}{24}$