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NEET 1988 (AIPMT) · AC Generator & Transformer

AC Generator & Transformer question from NEET 1988 (AIPMT)

Q61NEET 1988 · AIPMTMedium

AC Generator & Transformer

In a region of magnetic induction B=10−2B = 10^{-2} tesla, a circular coil of radius 30 cm and resistance π2\pi^2 ohm is rotated about an axis which is perpendicular to the direction of BB and which forms a diameter of the coil. If the coil rotates at 200 rpm the amplitude of the alternating current induced in the coil is

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Answer: (c)

  1. Peak emf e0=NBAωe_0 = NBA\omega with N=1N = 1.
  2. A=π(0.3)2=0.09π m2A = \pi(0.3)^2 = 0.09\pi\text{ m}^2, ω=2π×20060=20π3 rad/s\omega = \dfrac{2\pi \times 200}{60} = \dfrac{20\pi}{3}\text{ rad/s}
  3. e0=10−2×0.09π×20π3=6π2×10−3 Ve_0 = 10^{-2} \times 0.09\pi \times \dfrac{20\pi}{3} = 6\pi^2 \times 10^{-3}\text{ V}
  4. I0=e0R=6π2×10−3π2=6 mAI_0 = \dfrac{e_0}{R} = \dfrac{6\pi^2 \times 10^{-3}}{\pi^2} = 6\text{ mA}
  5. So the answer is (c) 6 mA.
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