Question

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

• A. $175\hat{k}N-m$
• B. $150\hat{k}N-m$
• C. $75\hat{k}N-m$
• D. $25\sqrt{37}\hat{k}N-m$

Answer 1

The correct option is B $150\hat{k}N-m$

$\overrightarrow{m}=50\hat{i}A{m}^2$
$\overrightarrow{B}=(0.5\hat{i}+30\hat{j})T$
$\overrightarrow{z}=\overrightarrow{m}\times \overrightarrow{B}$
$=50\hat{l}\times c0.5\hat{i}+3.0\hat{j}$
$=50\times 3k$
$=150\hat{k}Nm$