Consider a circuit with a 20 volt battery and a resistor (no other components).
Next, let's say I choose a point A on the positive terminal of the battery. The current flows from point A, around the circuit, back to point A, which results in an electric potential difference of 0 (since we're moving back to A).
However, if we were to add a resistor, wouldn't this violate Kirchhoff's Voltage Law? Let's say the resistor has a voltage drop of 20 volts. From earlier, the battery has a voltage drop of 20 volts.
Over the course of the circuit, the electric change in potential appears to be -40, not 0 (talking about current here, not electrons). Can someone tell me where I messed up? Thanks.