A magnetic compass needle oscillates 30 times per minute at a place where the dip is 45∘ and 40 times per minute where the dip is 30∘. If B1 and B2 are the net magnetic fields due to the earth at the two places respectively, then the ratio B1/B2 is approximately equal to
Held on 12 Apr 2019 · Verified 6 Jul 2026.
3.6
1.8
1.2
0.7
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A short bar magnet placed with its axis at $30^{\circ}$ with an external field of 800 Gauss, experiences a torque of $0.016 \mathrm{~N}. \mathrm{m}$. The work done in moving it from most stable to most unstable position is $\alpha \times 10^{-3} \mathrm{~J}$. The value of $\alpha$ is $\_\_\_\_$.
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