Question

A magnet of magnetic moment $\left(50\hat{i}\right){\text{A - m}}^2$ is placed in a magnetic field, $\overrightarrow{B}=(0.5\hat{i}+3.0\hat{j})\text{T}$. The torque acting on the magnet is

• A. $\left(175\hat{k}\right)\text{N - m}$
• B. $\left(150\hat{k}\right)\text{N - m}$
• C. $\left(275\hat{k}\right)\text{N - m}$
• D. $\left(250\hat{k}\right)\text{N - m}$

Answer 1

The correct option is B $\left(150\hat{k}\right)\text{N - m}$

Torque,

$\overrightarrow{\tau }=\overrightarrow{M}\times \overrightarrow{B}$

$\Rightarrow \overrightarrow{\tau }=\left(50i\right)\times (0.5\hat{i}+3.0\hat{j})$

$=\left(150\hat{k}\right)\text{N - m}$

Hence, option $\left(B\right)$ is the correct answer.