Question

Following figures show the arrangement of bar magnets in different configurations. Each magnet has magnetic dipole $\overrightarrow{m}$. Which configuration has highest net magnetic dipole moment?

• A. a
• B. b
• C. c
• D. d

Answer 1

The correct option is C c

(a) $M_{net}=\sqrt{m^2+m^2+2mmcos{90}^o}=\sqrt{2}m$

(b) $M_{net}=m-m=0$

(c) $M_{net}=\sqrt{m^2+m^2+2mmcos{30}^o}=m\sqrt{2+\sqrt{3}}$

(d) $M_{net}=\sqrt{m^2+m^2+2mmcos{60}^o}=\sqrt{3}m$

is configuration (c) $\theta$ is least so $M_{net}$ is maximum.