Question

When the current in a coil is changed from 2 A to 4 A in 0.05 second ,the emf induced in the coil is 8V. The self inductance of coil is

Answer 1

Dear student,
$$\begin{gathered} FromthecombinationofFaraday\text{'}sandLenzlaw, \\ wecanwrite \\ \epsilon =-\frac{d\phi }{dt} \\ \epsilon =inducedemf \\ \phi =magneticflux=Li \\ L=selfinduction \\ I=current \\ Theinducedemfinthecoilisgivenby \\ \epsilon =-\frac{d\left(Li\right)}{dt}=-L\frac{di}{dt} \end{gathered}$$

$$\begin{gathered} Given, \\ \epsilon =8Volt \\ di=2-4=-2Amp \\ dt=0.05Sec \\ then, \\ L=-\epsilon \frac{dt}{di} \\ \Rightarrow L=-8\frac{0.05}{(-2)}=0.2Henry \end{gathered}$$
Hence, the self induction of the coil is 0.2 H


Regards,