The switch in figure 1 has been closed for a long time. At t=0, the switch is opened. How would you estimate: (i) the initial condition (ii) the current through the inductor, i(t) for t > 0 ?

Here are the solutions to the remaining questions:

Q.1 (c) The switch in figure 1 has been closed for a long time. At t=0, the switch is opened. How would you estimate:

(i) the initial condition

(ii) the current through the inductor, i(t) for t > 0 ?

Step 1: Analyze the circuit for $t < 0$ (steady state with switch closed).
When the switch is closed for a long time, the circuit is in DC steady state. The inductor acts as a short circuit.
The 20 Ohm resistor is in series with the parallel combination of the 40 Ohm resistor and the 30 Ohm resistor. The inductor is in series with the