Correct Answer - Option 3 : 4
Concept:
Emf induced in an inductor is given by
\(ϵ = L\frac{{dI}}{{dt}}\)
Where ϵ = induced voltage
L = inductance of inductor
I = current through inductor
Calculation:
Given,
The induced voltage, ϵ = 40 V
Time, t = 0.4 s
Current I1 = 5 A
Current, I2 = 1 A
dI = I2 – I1 = (1 – 5)A = -4 A
Change in current = |dI| = 4A
dt = 0.4 s
\(ϵ = L\frac{{dI}}{{dt}}\)
\(\Rightarrow 40 = L \times \frac{{4}}{0.4}\)
\(L = \frac{{40}}{{10}} = {4\;H}\)