A small piece of metallic wire is moved across the gap between the pole pieces of a magnet in 0.4 s. The magnetic flux between pole pieces is 16 x 10– 4 Wb. The magnitude of induced e.m.f in wire will be:
Answer & explanation
Correct answer: option 1
The correct answer is Option (1) → 4 x 10–3 V
By Faraday’s law, the magnitude of the average induced emf equals the rate of change of magnetic flux. Moving across the whole gap, the wire sweeps through all the flux between the pole pieces in 0.4 s.
\( \displaystyle |\varepsilon| = \frac{\Delta\phi}{\Delta t} \)
\( \displaystyle |\varepsilon| = \frac{16\times10^{-4}\,\mathrm{Wb}}{0.4\,\mathrm{s}} \)
\( |\varepsilon| = 4\times10^{-3}\,\mathrm{V} \)