The current in a coil with a self-inductance of $L=25 \mathrm{mH}$ is decreased uniformly from $15 \

Question

The current in a coil with a self-inductance of $L=25 \mathrm{mH}$ is decreased uniformly from $15 \mathrm{~A}$ to $5 \mathrm{~A}$ in $2 \mathrm{milliseconds}$. The magnitude of the e.m.f. induced in the inductor during this process is

Professor PC Thomas Classes · Answer

(c) : The magnitude of the induced electromotive force (e.m.f.) is given by Faraday's law of induction for a self-inductor: $|\varepsilon| = L \left| \frac{di}{dt} ight|$. We are given $L = 25 	imes 10^{-3} \mathrm{H}$, change in current $|di| = |5 \mathrm{~A} - 15 \mathrm{~A}| = 10 \mathrm{~A}$, and the time interval $dt = 2 	imes 10^{-3} \mathrm{s}$. Substituting these values: $|\varepsilon| = 25 	imes 10^{-3} 	imes \left( \frac{10}{2 	imes 10^{-3}} ight) = 25 	imes 5 = 125 \mathrm{~V}$.