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MHT CET 2020 (16 Oct, Shift 2) · Earth's Magnetism

Earth's Magnetism question from MHT CET 2020 (16 Oct, Shift 2)

Q7MHT CET 2020 · 16 OCT · SHIFT 2Medium

Earth's Magnetism

If the angle of dip at places AA and BB are 30∘30^\circ and 45∘45^\circ respectively, then the ratio of horizontal component of earth's magnetic field at AA to that at BB will be

[sin⁡45∘=cos⁡45∘=12,sin⁡π6=12,cos⁡π6=32]\left[\sin 45^\circ = \cos 45^\circ = \frac{1}{\sqrt{2}}, \sin\frac{\pi}{6} = \frac{1}{2}, \cos\frac{\pi}{6} = \frac{\sqrt{3}}{2}\right]

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Answer: (c)

  1. H=BEcos⁡δH = B_E\cos\delta; taking the same total field BEB_E at both places,
  2. HAHB=cos⁡30∘cos⁡45∘=3/21/2=32\frac{H_A}{H_B} = \frac{\cos 30^\circ}{\cos 45^\circ} = \frac{\sqrt{3}/2}{1/\sqrt{2}} = \frac{\sqrt{3}}{\sqrt{2}}
  3. So the answer is (c) 3:2\sqrt{3} : \sqrt{2}.
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