Question

A magnet of magnetic moment M and pole strength m is divided in two equal parts, then magnetic moment of each part will be

• A. M
• B. $\frac{M}{2}$
• C. $\frac{M}{4}$
• D. 2M

Answer 1

The correct option is B $\frac{M}{2}$

If cut along the axis of magnet of length l, then new pole strength $m^{\prime }=\frac{m}{2}$ and new length l' = l
$\therefore$ New magnetic moment $M^{\prime }=\frac{m}{2}\times l=\frac{ml}{2}=\frac{M}{2}$

If cut perpendicular to the axis of magnet, then new pole strength m'=m and new length, $l^{\prime }=\frac{l}{2}$
$\therefore$ New magnetic moment $M^{\prime }=m\times \frac{l}{2}=\frac{ml}{2}=\frac{M}{2}$