CBSE Class 12 Physics 2017 Delhi Set 1 Paper

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Question : 3
Total: 26
At a place, the horizontal component of earth's magnetic field is B and angle of dip is 60∘. What is the value of horizontal component of the earth's magnetic field at equator?
Solution:  
‌BH=BE‌cos‌δ
‌BH=BE‌cos‌60∘⇒BE=2BH
At equator δ=0∘

∴‌‌BH=2B‌cos‌0∘=2B
[Alternatively, award full one mark, if student doesn't take the value (=2B) of BE while finding the value of horizontal component at equator, and just writes the formula only.]
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