Fig. 4.21 shows an initially relaxed R–L circuit in which step response is considered.
Fig. 4.21 R–L series circuit
The circuit equation is given by
Taking Laplace transform of Eq. (4.75), it can be written as follows,
Since circuit is initially relaxed i.e., de-energized hence i (0–) = 0
Taking inverse Laplace transform of Eq. (4.77), it can be written as follows,