(adsbygoogle = window.adsbygoogle || []).push({}); 1. The problem statement, all variables and given/known data

An coil has 4000 turns of wire and a mean area of cross-section 25cm^2. A magnetic field of flux density 0.16T passes through it. When the magnetic field is reduced steadily to zero in 0.0050s, emf is induced across the terminals of the coil. Calculate the value of this induced emf.

2. Relevant equations

E = N D Φ /Dt

3. The attempt at a solution

E = 4000 X (0.25 X 0.16) ÷ 0.0050 = 32 X 10^3V?

Or heres another solution

Ɛ = - N∆Φ / ∆t

25 cm² = 25 x 10^-4 m²

Φ = NBA = 4000 turns x 0.16 T x (25 x 10^-4 m²) = 1.6 Wb

Ɛ = - (4000 turns x 1.6 Wb) / 0.0050 s = - 1.28 x 10^6 V or - 1.28 MV

Please help. The second one seems more logical however I'm not sure its right. Thanks

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# Homework Help: Magnetic fields and induced EMF

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