Took a leaf out of Eileen's book for the picture corresponding to the problem (you have to delete the spaces in 'h t t p :'):
h t t p ://img444.imageshack.us/img444/1057/circuit6pk4.png
In the circuit that is in the link above, the switch S is initially in the open position and the capacitor C is initially uncharged. A voltage probe and a computer (not shown) are used to measure the potential difference across the capacitor as a function of time after the switch is closed. The graph produced by the computer is shown below right. The battery has an emf of 20V and negligible internal resistance. Resistor R1 has a resistance of 15k-ohms and the capacitor C has a capacitance of 20 micro-farad.
a) Determine the voltage across resistor R2 immediately after the switch is closed.
b) Determine the voltage across the resistor R2 a long time after the switch is closed.
c) Calculate the value of the resistor R2.
d) Calculate the energy stored in the capacitor a long time after the switch is closed.