Question

A magnet of dipole moment $2A{m}^2$ is deflected through ${30}^o$ from magnetic meridian. The required deflecting torque is $(B_H=0.4\times {10}^{-4}T)$:

• A. $0.4\times {10}^{-4}Nm$
• B. $0.4Nm$
• C. $0.2\times {10}^{-4}Nm$
• D. None of these

Answer 1

Answer: (A)

$0.4\times {10}^{-4}Nm$

Given : $\mu =2$ $A{m}^2$ $B_H=0.4\times {10}^{-4}$ $T$

Angle between $\overrightarrow{\mu }$ and $\overrightarrow{B_H}$: $\theta ={30}^o$

Torque, $\tau =\mu B_H$ $\sin \theta$

$\therefore$ $\tau =2\times 0.4\times {10}^{-4}$ $\times 0.5=0.4\times {10}^{-4}$ $Nm$