Question

What are the values of the self-induced emf in the circuit of the previous problem at the times indicated therein?

Answer 1

Given:
Self-inductance, L = 1 H
For an inductor of self-inductance L, the emf induced is given by
e = L$\frac{di}{dt}$

(a) At t = 100 ms,
$\frac{di}{dt}$ = 0.27 A/s
∴ Induced emf, e = L$\frac{di}{dt}$ = 1 × 0.27 = 0.27 V

(b) At t = 200 ms,
$\frac{di}{dt}=0.036$ A/s
∴ Induced emf = L$\frac{di}{dt}$ = 1 × 0.036 = 0.036 V

(c) At t = 1 s,
$\frac{di}{dt}$ = 4.1 × 10⁻⁹ A/s
∴ Induced emf = $L\frac{di}{dt}$ = 4.1 × 10⁻⁹ V