The magnitude of the induced emf in a coil of inductance $30 \mathrm{mH}$ in which the current changes from…

The magnitude of the induced emf in a coil of inductance $30 \mathrm{mH}$ in which the current changes from $6 \mathrm{~A}$ to $2 \mathrm{~A}$ in 2 $\mathrm{s}$ is
  1. $0.06\ V$
  2. $0.6\ V$
  3. $1.06\ V$
  4. $6\ V$

Solution

$\begin{aligned} & \text { } e=-L \frac{d l}{d t} \Rightarrow e=-30 \times 10^{-3} \times\left(\frac{2-6}{2}\right) \\ & =+30 \times 10^{-3} \times \frac{4}{2}=+0.06 \mathrm{~V}\end{aligned}$

Asked in: AP EAMCET 2015

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