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. $M / 2$
• C. $M / 4$
• D. $2 M$

Answer 1

Answer: (B)

$M / 2$

Answer 2

If cut along the axis of magnet of length l, then new pole strength $m ^ { \prime } = \frac { m } { 2 }$and new length $l ^ { \prime } = l$

$M ^ { \prime } = \frac { m } { 2 } \times l = \frac { m l } { 2 } = \frac { M } { 2 }$

If cut perpendicular to the axis of magnet, then new pole strength $l ^ { \prime } = l / 2$

$\therefore$ New magnetic moment $M ^ { \prime } = m \times \frac { l } { 2 } = \frac { m l } { 2 } = \frac { M } { 2 }$