Question

A magnetic dipole of dipole moment $10(\hat{i}+\hat{j}+\hat{k})$ is placed in a magnetic field $0.6\hat{i}+0.4\hat{j}+0.5\hat{k}$ , force acting on the dipole is :

• A. $\hat{i}+\hat{j}-2\hat{k}$
• B. $\hat{i}+\hat{j}+2\hat{k}$
• C. zero
• D. none of these

Answer 1

Answer: (A)

$\hat{i}+\hat{j}-2\hat{k}$

Given that,

Dipole moment, $m=10(\hat{i}+\hat{j}+\hat{k})$

Magnetic field, $B=0.6\hat{i}+0.4\hat{j}+0.5\hat{k}$

We know,

Force, $\tau =m\times B$

$\tau =(10\hat{i}+10\hat{j}+10\hat{k})\times (0.6\hat{i}+0.4\hat{j}+0.5\hat{k})$

$\tau =\hat{i}-\hat{j}-2\hat{k}$

Hence the force acting on the dipole is $\hat{i}-\hat{j}-2\hat{k}$.