question_answer

A magnetic dipole is acted upon by two magnetic fields which are inclined to each other a tan angle of 75°. One of the fields has magnitude of 15mT. The dipole attains stable equilibrium at an angle 30° with this field. The magnitude of the other field (in mT) is close to:                              [JEE ONLINE 09-04-2016]

A) 11

B) 1060

C) 36

D) 1

Correct Answer: A

Solution :

[a]

\[{{B}_{1}}\sin {{30}^{o}}=B2\sin {{45}^{o}}\]

\[{{B}_{2}}\frac{{{B}_{1}}}{\sqrt{2}}=10.60mT\approx 11mT\]