# Discharging an RC Circuit

## Homework Statement

RC circuit, with a resistor, capacitor and a switch with
ΔVC =80V R=1.5MΩ C=22μF
The switch is initially open. The switch is closed at t=0
(a) What is the charge in the capacitor when the current is 33μA
(b) How times does it take for the current to reach 33μA
2. The attempt at a solution
(a) So I think the capacitor is discharching.
Since ΔVC -IR=0, and ΔVC=Q/C is the charge when I=33μA
Q=IRC?
(b) If part (a) is correct, can I use Q=Q0 e-t/RC and find the time from there?

## Answers and Replies

Homework Helper
Gold Member
It looks correct to me. For part b, how do you compute ## Q_o ##? I don't think you showed that.

Moolisa
It looks correct to me. For part b, how do you compute ## Q_o ##? I don't think you showed that.
Is it C(80V)?