# Determining Current Direction in a Charging RC Circuit

• jolly_math
In summary, when the switch is closed, current flows clockwise from the battery to resistor R1 and down through the switch. For the capacitor, it is fully charged when the switch is closed and then discharges through resistor R2. The direction of current for a charging capacitor is determined by the direction of the flow of charge, which is from the positive plate to the negative plate.
jolly_math
Homework Statement
In the diagram below, the switch S has been open for a long time. It is then suddenly closed. TakeEe = 10.0 V, R1 = 50.0 kΩ, R2 = 100 kΩ, and C = 10.0 µF. Let the switch be closed at t = 5.0 s. Determine the current in the switch as a function of time.
Relevant Equations
I(t) = -I/RC * e^(-t/RC)

After the switch is closed, current flows clockwise from the battery to resistor R1 and down through the switch.

I don't understand the reasoning for the following: the current from the capacitor flows counterclockwise and down through the switch to resistor R2. How do I determine the direction of current when a capacitor is charging? Thank you.

jolly_math said:
I don't understand the reasoning for the following: the current from the capacitor flows counterclockwise and down through the switch to resistor R2. How do I determine the direction of current when a capacitor is charging? Thank you.
This capacitor is fully charged when the switch is closed. At that point the battery is effectively disconnected from the capacitor and the capacitor discharges through ##R_2##. Are you asking about a different problem?

jolly_math and vanhees71

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