Question

The current in a coil of self inductance 5 mH changes from $2\cdot 5$ A to $2\cdot 0$ A in $0\cdot 01$ second. Calculate the value of self induced emf.

Answer 1

Self inductance of the coil $L=5mH=0.005H$

Rate of change of current $\frac{di}{dt}=\frac{2.0-2.5}{0.01}$

$⟹$ $\frac{di}{dt}=-50$ $A/s$

Thus induced emf $E=-L\frac{di}{dt}$

$\therefore$ $E=-0.005\times (-50)$

$⟹$ $E=0.25V$