I am a beginner to electronics, so please excuse my ignorance. I have been searching endlessly for an explanation, but nothing I have read has fully answered my question.

Am I correct to say that in AC the hot wire and neutral wire fluctuate between positive and negative at a rate of $60 hertz$ (North American talking here)?

I could accept that, but my understanding from electron flow is that the positive is the return path and has voltage on it because it has the highest potential. The electrons flow out of the negative side and it has $0V$ because it has the lowest potential.

In AC, the neutral is always the return path. How can both be true at the same time? If neutral is always return, to me that would imply it is always positive. However, if neutral is the reference point with the least potential, then doesn’t that imply that neutral is always negative? It just doesn’t make sense to me.

  • $\begingroup$ Do you know that current flows in the opposite direction of electrons? i.e., electron flows from the negative end to positive end while, the current flows from the positive to negative. $\endgroup$
    – lee
    Jan 20 at 6:25
  • $\begingroup$ Isn't that the conventional current theory? I thought it was incorrect but was used anyway. $\endgroup$ Jan 20 at 6:27
  • $\begingroup$ Does this help you? $\endgroup$
    – lee
    Jan 20 at 6:30

Lets forget about your wall plugs and just talk about a general AC circuit.

You are not correct in saying "the hot wire and neutral wire fluctuate between positive and negative", only the hot wire is fluctuating(120sint), the neutral wire is grounded (0V), and so the potential difference between the two lines is 120sint - 0 = 120sint. When you connect a device to your walls, the voltage oscillates back and forth, there is no "return path" because in theory the electrons are just shaking back and forth. Remember it is electron movement that creates power not necessarily "flow". This is for a pure AC circuit.

Now the circuits you are talking about(in home) are in a 3-Phase network where you need to return some power in the source to keep the loads on your 3 Phases balanced, I assume you don't know about 3-Phase power so I won't focus on it, but that is where the idea of a "return path" comes from, and why it is not a thing if you are building an AC circuit on a breadboard, but it comes up during home power.

It is much easier to discuss circuits from the framework of Power and then apply that to electrons, as opposed to discussing electrons in terms of voltage and current.

  • $\begingroup$ This isn't what I was asking... $\endgroup$ Jan 20 at 6:14
  • $\begingroup$ Oh lmao you were just asking about how AC works, gimme a minute I'll update. $\endgroup$ Jan 20 at 6:18
  • $\begingroup$ I did, specifically about how electron flow theory applies. I gave the example of how EFT works in DC but I'd appreciate some help applying it to AC. $\endgroup$ Jan 20 at 6:22
  • $\begingroup$ What is "sint" as in 120sint? $\endgroup$ Jan 20 at 6:33
  • 1
    $\begingroup$ Exactly! This becomes really clear when using a scope on AC circuits. Yes I mean AC Voltage -> AC Current and charge is just the time integral of Current, so you have an AC charge distribution, i.e. no net motion. $\endgroup$ Jan 20 at 6:44

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