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JEE Main 2023 (1 Feb, Shift 2) · Magnetic Flux & Faraday's Law

Magnetic Flux & Faraday's Law question from JEE Main 2023 (1 Feb, Shift 2)

Q40JEE Main 2023 · 1 FEB · SHIFT 2Easy

Magnetic Flux & Faraday's Law

A coil is placed in magnetic field such that plane of coil is perpendicular to the direction of magnetic field. The magnetic flux through a coil can be changed:

A. By changing the magnitude of the magnetic field within the coil.

B. By changing the area of coil within the magnetic field.

C. By changing the angle between the direction of magnetic field and the plane of the coil. D. By reversing the magnetic field direction abruptly without changing its magnitude. Choose the most appropriate answer from the options given below:

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Answer: (b)

  1. Φ=BAcos⁡θ\Phi = BA\cos\theta, so flux changes if BB, AA or θ\theta changes.
  2. A: changing BB changes Φ\Phi. B: changing AA changes Φ\Phi. C: changing the angle changes cos⁡θ\cos\theta.
  3. D: reversing B⃗\vec{B} takes Φ\Phi from +BA+BA to −BA-BA; the magnitude of Φ\Phi is unchanged, which is why the official answer leaves it out.
  4. So the answer is (b) A, B and C only.
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