I hope all is well.
In this post, I’ve asked a couple of very fundamental questions regarding the topic of electrical engineering that my current education vaguely answered—and unsatisfactorily so since it was mainly through the use of analogies—and that my current schedule prohibits the “deep dive” that their answers most likely require. In either case, if pointing me towards the right resources might be a better option than answering them, please also let me know.
My first question is regarding voltage. I think it might me more productive that I explain my current understanding of the topic. Through my current education, we first started with point charges in space. From there we learned about electrical force, electrical field, and then voltage. But this understanding becomes vague —at least in my mind—when we start talking about circuits. Voltage has the unit J/C. We can easily multiply the unit by the appropriate unit ratio (charge per electron, or 1.602 x 10^(-19) coulombs) to get some joules per one electron. We also can assume that this energy per electron comes from the kinetic energy of the electron, which of course depends on its mass and speed (and, for the purposes of the question, let’s also assume that the mass does not change). Now, here’s the question: When a battery reads 5V vs another battery reading 10V, does that mean that every electron that moves through the circuit connected to the second battery does more work than any electron moving in the circuit connected to the first battery? If so, does this mean that those corresponding electrons move at different speeds? Lastly, does this mean that we’d have an upper limit on how absolutely high a voltage value can get (the limit being set by the speed of light)?
My second question is about resistance. Across any component on a circuit (or even a length of wire, in the “real” world) we can observe a voltage drop. If we could get a microscope that somehow allowed us to see the path of electrons going through any of these components, what do we actually see? Do the electrons slow down? How does this voltage drop (and the dissipated energy) actually look like?
Thank you again for reading through this long post. Please let me know if anything I’m asking is unclear.
UPDATE: I’ve edited my question based on DKNguyen’s answer:
Firstly, thank you so very much for the detailed response. I’ve wrote a follow up below:
Higher voltage means the more work can be performed per electron. Bt it doesn't mean the more work can be performed by the one same one electron. Why this distinction?
Because the physical electron itself doesn't actually move through the entire circuit very quickly similar to how individual air molecules do not travel with the sound wave. Air molecules actually moving is wind, not sound and travels far slower than sound. Similarly, the electrons move through the conductor much more slowly than the electrical energy/wave does.
Got it. Then if we could actually look “inside” of a wire connected in, let’s say, a DC circuit, we’d see each electron being “pulled” towards the positive terminal while the electron immediately “behind” it gets “pulled” to the empty space (created by the first electron). Right?
There's just a general limit in physics where if you cram too much energy into a space, it becomes a black hole. So I guess yes? I think other stuff happens first though in this case...like the electron turning into something else after you pump so much energy into it. At least, that's what the math says anyways.
Thank you for your response, though the answer to one of my questions is still remains: let’s say you have 2 circuits—one powered by a 5V battery and the other by a 10V battery (the circuits are otherwise completely identical). Let’s say you can somehow peer into the wire leaving the (-) terminal of the battery for both circuits, and you can actually see the individual electrons “in action.” How is what you see in circuit 1 different from circuit 2?
You see electrons bumbling back and forth, not at all traveling down the wire as you might imagine. The energy they carry travels far and fast, but individual electrons don't travel very far or fast over long distances. Bumbling around as they are, they do travel at different speeds, and in different directions not just down the length of the wire. On average they have a "drift" velocity which is the motion of the physical electrons you are asking about but this isn't the same as the speed at which the energy in the electrical wave is propagated. For 60Hz mains AC , the electrons themselves aren't traveling all the way back and forth between your house and the power plant at 60 times per second.
Thank you again, though my question about resistance still remains. Let’s say, again, you have 2 circuits each composed of a battery, a resistor, a switch, and the circuits connecting the components. The only difference between these circuits is in the resistance value of the resistors: 50 ohms vs 100 ohms. Again, let’s see you can somehow peer into the resistors and can see the electrons “in action.” You flip the switch to “on” in the first circuit, and immediately look “into” the resistor in circuit one. Then you do the same for the second circuit. How is what you see different in both circuits?
Thank you again.