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AP EAMCET · PHYSICS · Electromagnetic Induction

A coil of 45 turns and radius 4 cm is placed in a uniform magnetic field such that its plane is perpendicular to the direction of the field. If the magnetic field increases from 0 to 0.70 T at a constant rate in a time interval of 220 s, then the induced emf in the coil is

  1. A 0.32 mV
  2. B 0.50 mV
  3. C 0.72 mV
  4. D 0.96 mV
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Answer & Solution

Correct Answer

(C) 0.72 mV

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Detailed explanation

\(A = \pi r^2 = \pi (0.04 \text{ m})^2\) \(\frac{dB}{dt} = \frac{0.70 \text{ T}}{220 \text{ s}}\) \(\varepsilon = N A \frac{dB}{dt} = 45 \times \pi (0.04 \text{ m})^2 \times \frac{0.70 \text{ T}}{220 \text{ s}} \approx 0.00072 \text{ V} \approx 0.72 \text{ mV}\)
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