00:01
Okay, our goal is to find i -0 as a function of t, the switch is closed at t equals zero.
00:07
So for t less than zero, all currents are zero.
00:16
Presumably, the switch has been open a long time, so any current in the capacitor has been damped out.
00:23
All right, now, to simplify matters, i am going to reduce the circuit.
00:38
So these two resistors are in series.
00:47
So to combine, they make 12k.
00:52
And if i take that 12k, it's in parallel with this one.
01:13
All right.
01:15
And that combination is two 12ks in parallel.
01:31
It comes out to be 6k.
01:36
Okay.
01:38
And then these two resistors, they are in parallel.
01:46
So that's 4 times 12, 4 plus 12, 2 .4k...