00:01
We have an rz circuit shown the left here, where r is equal to 6 kilo -ooms and the capacitance is equal to 14 micro -farrants.
00:15
Or that is also equal to 14 times 10 to the negative 6 ferrets.
00:20
So if the capacitor is initially charged at a voltage of, let's say, v0, 13 volts, when the switch is closed, how long does it take for the current running in the circuit to go 38 % of its initial value? so 38 % of its initial value, it can write it as i of t divided by the initial current, is equal to 0 .308.
00:53
So the unknown in this problem is the time to reach that 0 .38 ratio.
01:00
So this is a case of a discharging capacitor, and the equation of current for a discharging capacitor is equal to i of t is equal to i0 or the initial current times e raised to the negative t over the systems times capacitors.
01:26
So in order to solve for t, we need to isolate the exponential factor.
01:32
So we divide both sides by i0...