Question
Please show me where I went wrong!
In the circuit of the figure below, the switch S has been open for a long time. It is then suddenly closed. Take = 10.0 V, R1 = 50.0 k ohm, R2 = 195 k ohm, and C = 10.0 mu F. Determine the time constant before the switch is closed. Can you combine the two resistors into a single equivalent resistance? S Determine the time constant after the switch is closed. S Let the switch be closed at t = 0. Determine the current in the switch as a function of time. (Use the following as necessary: t. Express your answer in units of mu A.)
Explanation / Answer
a) t = Rb* C = 1.5*10^5 * 10*10^-6 = 1.5 s
b) after = Ra * c = 1.95*10^5 *10*10^-6 = 1.95 s
c) I battery = 10 v /50 k ohms = 200 mue A
I from capacitor = Ib e^(-t/Rc) = 10 / 192 k ohms e^-t/1.95
total current = Ib + Ic = 200 mueA + 521mue e^-t/1.95s