A circular loop of radius 0.1 m with 100 turns is in a magnetic field of 0.2 T. If the field decreases to 0.1 T in 0.01 s, the induced emf is:
Correct answer: A. 31.4 V
- A. 31.4 V
- B. 62.8 V
- C. 15.7 V
- D. 7.85 V
Explanation
Induced emf = ε = N(ΔΦ/Δt), where Φ = BA, A = π(0.1)2= 0.0314 m2, ΔB = 0.2 - 0.1 = 0.1 T, Δt = 0.01 s, N = 100. Thus, ΔΦ = 0.1 × 0.0314 = 0.00314 Wb, ε = 100×0.0314×0.1/0.01 =31.4V.
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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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