For two inductively coupled coils, the mutual inductance is 1.9 H. The current through the primary changes by 6 A in 1 ms. The induced emf in the secondary is
Answer & explanation
Correct answer: option 3
The correct answer is Option (3) → 11.4 kV
By mutual induction, a changing current in the primary induces in the secondary an emf of magnitude \( \varepsilon=M\,\Delta I/\Delta t \), where \( M \) is the mutual inductance.
\( \Delta t=1\,\mathrm{ms}=10^{-3}\,\mathrm{s} \)
\( \begin{aligned} \varepsilon &= M\,\frac{\Delta I}{\Delta t} \\ &= 1.9\,\mathrm{H}\times\frac{6\,\mathrm{A}}{10^{-3}\,\mathrm{s}} \\ &= 1.14\times10^{4}\,\mathrm{V} \\ &= 11.4\,\mathrm{kV} \end{aligned} \)