• # question_answer An average induced e.m.f. of 1 V appears in a coil when the current in it is changed from 10 A in one direction to 10 A in opposite direction in 0.5 sec. Self-inductance of the coil is A)  25 mH      B)  50 mHC)  75 mH       D)  100 mH

$|e|=L\frac{di}{dt}\Rightarrow 1=\frac{L\times \{10-(-10)\}}{0.5}$ $\Rightarrow$ $L=25\,mH$