In the circuit of the figure below, the switch S has been open for a long time. It is then suddenly closed. (Use the following as necessary: ℰ for ℰ, R1, R2, t, and C.)
(a) Determine the time constant before the switch is closed.
(b) Determine the time constant after the switch is closed.
(c) Let the switch be closed at t = 0. Determine the current in the switch as a function of time.