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JEE Main 2019 (12 Jan, Shift 2) · Motional EMF

Motional EMF question from JEE Main 2019 (12 Jan, Shift 2)

Q47JEE Main 2019 · 12 JAN · SHIFT 2Medium

Motional EMF

A 10 m long horizontal wire extends from North East to South West. It is falling with a speed of 5.0 ms–1, at right angles to the horizontal component of the earth's magnetic field of 0.3 ×\times 10–4 Wb/m2. The value of the induced emf in wire is:

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Answer: (d)

  1. BHB_H points north; only the wire's component perpendicular to it (east–west) matters.
  2. NE–SW wire: effective length =10cos⁡45∘=7.07= 10\cos45^\circ = 7.07 m.
  3. ε=BHleffv=0.3×10−4×7.07×5≈1.06×10−3\varepsilon = B_H l_{eff} v = 0.3\times10^{-4} \times 7.07 \times 5 \approx 1.06\times10^{-3} V
  4. So the answer is (d) 1.1×10−31.1\times10^{-3} V.
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