A 9 V battery is connected in series with a 100 Ω resistor and 12µF capacitor. The capacitor is initially uncharged. What is the capacitive time constant of the circuit? How much charge q(t) is in the capacitor after two time constants?. What is the limiting value of the charge on the capacitor? When the battery is disconnected and the capacitor is discharged, what is the current i(t) in the circuit after two time constants? What is the limiting value of the current? Draw the curves q(t) and i(t) as functions of time and label them appropriately.

Question

A 9 V battery is connected in series with a 100 Ω resistor and 12µF capacitor. The capacitor is initially uncharged. What is the capacitive time constant of the circuit? How much charge q(t)  is in the capacitor after two time constants?.  What is the limiting value of the charge on the capacitor? When the battery is disconnected and the capacitor is discharged, what is the current i(t) in the circuit after two time constants?  What is the limiting value of the current?  Draw the curves q(t) and i(t) as functions of time and label them appropriately.

drwls · Answer

The time constant is RC and that the initial capacitor charge is q(0) = CV. That is basic stuff.

Show us what you know, look up and learn the equations, and don't expect us to do all the work here. You will learn the subject better that way.