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ELIF: Why is voltage at the end of a circuit 0?

In: Other

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The voltage must be 0 volts at the end because you have a consumer (e.g. a lamp) that needs all the voltage to work. If you end up with more than 0 volts, something is broken or wrongly connected.

Because the circuit and the battery ~~have~~ are connected at two places: The battery voltage at the top, the zero level at the bottom.

Fun fact 1: You can nominate the value out of the battery to be the zero, however the zero level is then suddenly (minus battery voltage).

Fun fact 2: If your load is rather low (say 2.5 ohm), you will find out that the voltage over the circuit isn’t 100% but 83% as the internal resistance of the battery is about 0.5 ohm.

Voltage is not a value that exists on its own.

Voltage tells the difference between two point.

In a circuit the starting point and the ending point are the same. So the voltage difference must be zero.

This is a pretty big simplification, but you can think of voltage between two points like this:

*”How interested would the electrons be in flowing from point A to point B, provided they are given a way to do so?”*

The voltage depends on a lot of different factors. As an example: Is it easy to get there? I.e. low resistance? Then the voltage increases, because the electrons are lazy and why would they take a harder path to get where they are going.

Usually, we’re being told you always have to close a circuit for electrons to flow anywhere. A broken circuit is, quite literally, one that won’t work. Really though, this is a quirk in the semantics. Electrons flow from the cathode to the anode, meaning the electrons flow from the – to the + . This if it as some kind of race, where – is the start and + is the finish line.

(Sidenote: this is opposite the current. The electrons flow ***against*** the current.)

The reason electron flow to the anode is because they are attracted to the positive charges there. Once they get there, to the end of the circuit, they have no reason to go anywhere else.

So, if you would ask the electron “How interested are you in going somewhere else?” they would reply with “Not at all interested”. If you ask them “What is the voltage?”, they’d say “0.”

What do you mean by that?

Do you mean Kirchoff’s voltage law, the rule that if you add up all the voltages and voltage losses around a circuit, you end up at zero?

The answer is simple – you start counting, adding and subtracting at a point, and you start adding and subtracting from zero. Then you go around the loop and end up at the same point. Of course the value is going to be back at zero – it is where you started!