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Question: Answered & Verified by Expert
Two concentric coils of 10 turns each are placed in the same plane. Their radii are 20 cm and 40 cm and carry  0.2 A  and  0.3 A current respectively in opposite directions. The magnetic induction (in tesla) at the center is
PhysicsMagnetic Effects of CurrentJEE Main
Options:
  • A 34μ0
  • B 54μ0
  • C 74μ0
  • D 94μ0
Solution:
2473 Upvotes Verified Answer
The correct answer is: 54μ0
Two coils carry currents in opposite directions, hence net magnetic field at centre will be difference of the two fields.

ie,    Bnet=μ04π . 2πNi1r1-i2r2

=10μ020.20.2-0.30.4

=54μ0

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