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JEE Main 2021 (27 Aug, Shift 2) · Motional EMF

Motional EMF question from JEE Main 2021 (27 Aug, Shift 2)

Q36JEE Main 2021 · 27 AUG · SHIFT 2Medium

Motional EMF

A constant magnetic field of 1T is applied in the x > 0 region. A metallic circular ring of radius 1m is moving with a constant velocity of 1 m/s along the x-axis. At t = 0s, the centre of O of the ring is at x = −-1m. What will be the value of the induced emf in the ring at t = 1s? (Assume the velocity of the ring does not change.)

Figure

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Answer: (c)

  1. At t=1t = 1 s the centre is at x=−1+1=0x = -1 + 1 = 0, on the field boundary.
  2. The ring cuts the boundary along a diameter: effective length =2R=2= 2R = 2 m.
  3. ε=B(2R)v=1×2×1=2\varepsilon = B(2R)v = 1 \times 2 \times 1 = 2 V
  4. So the answer is (c) 2 V.
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