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Question
An average emf of 20 V is induced in an inductor when the current in it is changed from 2.5 A in one direction to the same value in the opposite direction in 0.1 s. Find the self-inductance of the inductor.
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Solution
Let the self-inductance of the inductor be L.
Average emf induced in the inductor, V = 20 V
Change in current, di = i2 − i1 = 2.5 − (−2.5) = 5 A
Time taken for the change, dt = 0.1 s
The voltage induced in the inductor is given by
\[V = L\frac{di}{dt}\]
\[ \Rightarrow 20 = L\left( \frac{5}{0 . 1} \right)\]
\[ \Rightarrow 20 = L \times 50\]
\[ \Rightarrow L = \frac{20}{50} = \frac{4}{10} = 0 . 4 H\]
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