# Calculating capacitor voltage with initial conditions in an RC circuit If the initial voltage of the capacitor at 0s is 20V, would the equation for the voltage of the capacitor at a specific time be; 60 + (20-60)e^(-t/RC)

or would it be 80 - 60e^(-t/RC)

• It's unclear to me what the voltage is on the + terminal of your capacitor. It appears to be initially 0 volts given that - is at minus 20 and you appear to be stating that there is 20 volts across your capacitor. Oct 31 at 9:34
• The capacitor is initially charged to +20V- and the switch is closed at t=0s. In the other practice questions it is a full circuit. In this practice question it is not a full circuit and ends in -20V but is not explained why or what effect this has. Oct 31 at 9:39
• Then at t=0 the voltage on the left hand side of the capacitor is 0 volts. This is equivalent to charging the same capacitance (that is not pre-charged) and is connected to 0 volts on the RH side. Oct 31 at 9:41
• @Andyaka So would my initial formula of 60 + (20-60)e^(-t/RC) or would it be 80 - 60e^(-t/RC) Oct 31 at 10:04 