Question

The current in a coil changes from 4 ampere to zero in 0.1 s. If the average e.m.f. induced is 100 volt, what is the self inductance of the coil

• A. $2.5\mspace{6mu} H$
• B. $25H$
• C. $400\mspace{6mu} H$
• D. $40\mspace{6mu} H$

Answer 1

Answer: (A)

$2.5\mspace{6mu} H$

Answer 2

$e = L\frac{di}{dt} \Rightarrow 100 = L \times \frac{4}{0.1} \Rightarrow L = 2.5\mspace{6mu} H$