A current of 15A in the primary coil of a circuit is reduced to zero at a uniform rate in \( 10^{-6}\,\mathrm{s} \). If the coefficient of the Mutual Inductance is 4 H, what is the Induced emf in the secondary coil?
Answer & explanation
Correct answer: option 3
The correct answer is Option (3) → \( 6\times10^{7}\,\mathrm{V} \)
By mutual induction, a changing current in the primary induces in the secondary an emf proportional to the rate of change of the primary current.
\( \displaystyle |e| = M\,\frac{\Delta I}{\Delta t} \)
\( M = 4\,\mathrm{H} \)
\( \Delta I = 15\,\mathrm{A} \)
\( \Delta t = 10^{-6}\,\mathrm{s} \)
\( \displaystyle |e| = 4\,\mathrm{H} \times \frac{15\,\mathrm{A}}{10^{-6}\,\mathrm{s}} = 6\times10^{7}\,\mathrm{V} \)