A bar magnet of length $10 \mathrm{cm}$ and pole strength$2 \mathrm{A} \mathrm{m}$ makes an angle ${60}^{\mathrm{o}}$ with a uniform magnetic field of induction $50 \mathrm{T}$. The couple acting on it is

• Correct answer
  A

  $5\sqrt{3}\mathrm{ }\mathrm{N }\mathrm{m}$
• B

  $\sqrt{3}\mathrm{ }\mathrm{N }\mathrm{m}$
• C

  $10\sqrt{3}\mathrm{ }\mathrm{N }\mathrm{m}$
• D

  $20\sqrt{3}\mathrm{ }\mathrm{N }\mathrm{m}$

Hence, the correct answer is option: 'A'.