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A copper disc of the radius 0 . 1   m is rotated about its centre with ω = 20 revolutions per second in a uniform magnetic field of 0 . 1   T with its plane perpendicular to the field. The emf induced across the radius of the disc is

Options

  1. Aπ 2 0   V
  2. Bπ 10   V
  3. C20 π   mV
  4. D100 π   mV

Correct answer

C. 20 π   mV

Step-by-step solution

ε = B ω R 2 2 = 0.1 × 2 π × 2 0 0.1 2 2 = 2 0 π × 1 0 - 3   V

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