Question

A dipole of magnetic moment $\overline{m}=30\hat{j}A{m}^2$ is placed along the y-axis in a uniform magnetic field $\overline{B}=(2\hat{i}+5\hat{j})$ T. The torque acting on it is

• A. $-40\hat{k}Nm$
• B. $-50\hat{k}Nm$
• C. $-60\hat{k}Nm$
• D. $-70\hat{k}Nm$

Answer 1

The correct option is C $-60\hat{k}Nm$

Given that,

Magnetic moment of dipole, $\overrightarrow{m}=30\hat{j}A{m}^2$

Magnetic field , $\overrightarrow{B}=(2\hat{i}+5\hat{j})T$

Torque acting on it, $\overrightarrow{\tau }=\overrightarrow{m}\times \overrightarrow{B}=30\hat{j}\times (2\hat{i}+5\hat{j})=-60\hat{k}Nm$

So, the correct option is $C$