The self inductance of a coil is 200 μH, current changes by 1 A in 0.05 sec. What is the emf produced?
Answer & explanation
Correct answer: option 4
The correct answer is Option (4) → 4 mV
The emf induced in a coil by a changing current is given by self-induction, \( \varepsilon = L\left|\frac{\Delta I}{\Delta t}\right| \). Convert the inductance first: \( L = 200\,\mu\mathrm{H} = 200\times10^{-6}\,\mathrm{H} = 2\times10^{-4}\,\mathrm{H} \).
\( \displaystyle \varepsilon = 2\times10^{-4}\,\mathrm{H}\times\frac{1\,\mathrm{A}}{0.05\,\mathrm{s}} \)
\( \varepsilon = 4\times10^{-3}\,\mathrm{V} = 4\,\mathrm{mV} \)