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JEE Main 2019 (10 Jan, Shift 1) · Motional EMF

Motional EMF question from JEE Main 2019 (10 Jan, Shift 1)

Q46JEE Main 2019 · 10 JAN · SHIFT 1Medium

Motional EMF

A solid metal cube of edge length 2 cm is moving in a positive y-direction at a constant speed of 6 m/s. There is a uniform magnetic field of 0.1 T in the positive z-direction. The potential difference between the two faces of the cube perpendicular to the x-axis, is -

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Answer: (b)

  1. Force on charges qv⃗×B⃗q\vec v\times\vec B: j^×k^=i^\hat j \times \hat k = \hat i, so charges separate along xx.
  2. In equilibrium the faces normal to xx have V=BvdV = Bvd, with dd = edge.
  3. V=0.1×6×0.02=0.012V = 0.1 \times 6 \times 0.02 = 0.012 V
  4. =12= 12 mV. So the answer is (b).
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