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JEE Advanced2020PhysicsMagnetic Effects of CurrentActual

A circular coil of radius R and N turns has negligible resistance. As shown in the schematic figure, its two ends are connected to two wires and it is hanging by those wires with its plane being vertical. The wires are connected to a capacitor with charge Q through a switch. The coil is in a horizontal uniform magnetic field B o parallel to the plane of the coil. When the switch is closed, the capacitor gets discharg

Options

  1. Aπ 2 N Q B o R 2
  2. Bπ N Q B o R 2
  3. C2 π N Q B o R 2
  4. D4 π N Q B o R 2

Correct answer

B. π N Q B o R 2

Step-by-step solution

τ = M · B · sin   90 ° τ = N I π R 2 B 0 Δ L = ∫ 0 t τ · d t = N · π R 2 · B ∫ 0 t I   d t ; Δ L = N · π R 2 · B Q .

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