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A rectangular loop of area 0.05 m² with 30 turns is in a magnetic field of 0.6 T. If the field is reduced to zero in 0.03 s, the average induced emf is:

Correct answer: B. 60 V

  • A. 30 V
  • B. 60 V
  • C. 90 V
  • D. 120 V

Explanation

Induced emf = ε = NΔΦ/Δt, where Φ = BA, A = 0.05 m², ΔB = 0.6 - 0 = 0.6 T, N = 30, Δt = 0.03 s. Thus, ΔΦ = 0.6 × 0.05 = 0.03 Wb, ε = 30 × 0.03/0.03 = 60 V.

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Magnetic flux density and magnetic flux describe the strength of a magnetic field and the field passing through a surface. A charged particle moving through a magnetic field experiences a force perpendicular to its velocity and may follow circular or helical motion, depending on the angle between velocity and field.

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