Voltage Drop and Charge Flow

Question

I am hoping someone can help me with understanding voltage drop and charge flow. Here is what I think I know.

The voltage drop through a circuit must equal the voltage of the battery source, and there is also an electric field that is generated throughout the circuit which provides a force to move the electrons. If a voltage drop across a resistor causes the net voltage to be zero, then how does a current still exist? I first thought to answer this due to the electric field N/C providing a force on the electrons, but the force times a distance would equal Joules. Since J/C represents the units for voltage, and there is a voltage drop equal to the voltage of a battery, then how can charge still be flowing towards the end of the circuit?? I apologize if this question has already been asked on this site.. If so please point me that threads direction :)

Answer 1

I think you have some misconceptions about voltage. You mention "net voltage" but voltage is always a difference in electric potential. In a circuit, that means you never talk about a "net voltage" or a voltage at a certain point. Voltage is always meant to be read as "the voltage between two points" or "the voltage at A with respect to B." It is never just "the voltage at A." In that respect, there is no "end of the circuit." You can pick a point of the circuit to act as the reference point for all the other parts of the circuit but it wouldn't be correct to call that point the "end" of the circuit. That would be like asking where the end of a circle is or where the end of a square is.

Think of the water analogy. A battery is analogous to a water pump. Voltage is analogous to pressure difference. Flow of charge (electric current) is analogous to flow of water. A water pump creates a pressure difference which causes water to flow. If you have some pipe that is restricted (analogous to a resistor) so that it causes the pressure to drop, then you will still have the same flow of water after the pressure drop as before the drop. It is no different with electricity.

Answer 2

The net voltage around the entire circuit is zero. However, the voltage across the resistor is equal in magnitude and opposite in sign to the voltage inside the battery. You could view this conceptually as electrons flowing from the minus to the plus terminal (through the resistor) while the internal mechanism of the battery produces more electrons at one terminal and "collects" them at the other.