Question

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 and the pole strength of each bar are $I$ and $m$. The resultant magnetic moment of the system is :

• A. $ml$
• B. $\sqrt{2}\,ml$
• C. $\sqrt{3}\,ml$
• D. $2\,ml$

Answer 1

Answer: (B)

$\sqrt{2}\,ml$

Answer 2

Resultant magnetic moment is given by M = $\sqrt{M_1^2 + M_2^2} = \sqrt{(ml)^2 + (ml)^2} = ml \sqrt{2}$ = $\sqrt{2} ml$