In the circuit below, the capacitor is initially uncharged, and the switch is closed at t= 0. The circuit can be replaced by the "Thevenin" equivalent circuit where: RThevenin = (R1 in parallel with R2) in series with R3. VThevenin is the voltage across the capacitor (in the original circuit) when the switch has been closed for a long time. a) Find the value of RThevenin and Vthevenin b) Find the equation of the voltage across the capacitor as a function of time, Vc(t), and evaluate the expression at t = 40 ms. The switch remains closed for a long period of time so the capacitor is fully charged. The clock is reset to t=0 and the switch in the original circuit is opened at t=0. c) Find the new time constant of the circuit d) Find and expression for the voltage across resistor R2 ( VR2(t) ) and the time at which the voltage across R2 is 2V