Question

Two short magnetic dipoles, $m_1$ and $m_2$ each having magnetic moment of $1{\text{A-m}}^2$ are placed at points $O$ and $P$ respectively. The distance between $OP$ is $1\text{m}$. The torque experienced by the magnetic dipole $m_2$ due to the presence of $m_1$ is ______ $\times {10}^{-7}\text{N-m}$.

• A. 1.0
• B. 1
• C. 1.00

Answer 1

Answer: (A), (B), (C)

$\overrightarrow{\tau }={\overrightarrow{m}}_2\times {\overrightarrow{B}}_1$

$\Rightarrow \tau =m_2{B}_1\sin \theta =m_2\times \frac{{\mu }_0}{4\pi }\frac{m_1}{r^3}\times \sin \theta$

$\Rightarrow \tau =1\times \frac{{\mu }_0}{4\pi }\frac{1}{1^3}\times \sin {90}^{\circ }=1\times {10}^{-7}\text{N-m}$