Timeline for Why are circuits considered loops?
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9 events
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| Oct 14, 2017 at 3:43 | comment | added | alephzero | @dudewad Re "equalization", keep in mind one fact: the electrical force of repulsion between two electrons is very much bigger than the gravitational force - in fact, about 10,000,000,000,000,000,000,000,000,000,000,000,000,000 times bigger! So the limit on "how fast things equalize" is set by Einstein's theory of relativity (nothing can travel faster than light speed), and not by any "common sense real world" analogies between the "flow of current" and water flows, etc. | |
| Oct 14, 2017 at 3:35 | comment | added | alephzero | @dudewad Your idea of "some sort of equalization" being equivalent to "a current" (in some sense) isn't "wrong", but for most situation it's irrelevant, because the "equalization" would happen on a time scale of nanoseconds, and the time-varying current would also dissipate the energy into space as EM radiation. Of course if you wanted to understand why lightning strikes can interfere with radio transmissions, that is the right level of detail that you need, but it's not what most "circuit analysis" is concerned with. | |
| Oct 14, 2017 at 3:26 | comment | added | alephzero | ... you don't need quantum mechanics to figure out how to design a simple circuit containing a battery, an LED, and a resistor to limit the current, but if you want to understand how the LED actually works, in more detail than "when you pass a current through it, it lights up," then you most certainly do need to learn some quantum mechanics first! | |
| Oct 14, 2017 at 3:23 | comment | added | alephzero | @dudewad If you are just beginning to study circuits, take the idea of "loops" absolutely literally. But bear in mind that "loops" and only tell part of the story. If you want to explain what happens at the atomic level when a current flows through a wire, or what happens at high frequencies, or when electromagnetic radiation (e.g. radio transmission) is involved, or how any type of semiconductor device (even the most basic) works, you need much more theory than just "loops". But you have to start with simple ideas, and build on them ... | |
| Oct 14, 2017 at 3:17 | comment | added | WhatRoughBeast | @mkeith - I added the phrase specifically to account for electron guns and similar ion sources. And since electron guns used to be part of electronic circuits (although not configured to produce non-neutral components) I don't see how you can dismiss them. | |
| Oct 14, 2017 at 2:39 | comment | added | user57037 | Not only in the long run, but instantaneously also. I won't quibble over a few extra electrons fired from an electron gun or something, but from the perspective of circuit analysis, every circuit element must remain electrically neutral instantaneously as well as over the long run. | |
| Oct 14, 2017 at 2:26 | comment | added | user57037 | @dudewad, the loops are taken VERY literally. All circuit analysis is based on the loop. People love to point out exceptions that happen in very extreme situations. But you will literally find circuit analysis impossible if you convince yourself that charges can flow into a circuit element and stay there. The macroscopic physical world matches this behavior well enough that you probably don't have to worry about any exceptions. | |
| Oct 12, 2017 at 17:25 | comment | added | dudewad | But, could the negatively charged particles be stored, say, on one end of a hallway, and the receiving medium be placed on the other end? This would constitute not a loop but rather just some sort of an "equalization" so to speak. Does that make sense? I guess I'm trying to clarify whether "loops" is to be taken literally or not. | |
| Oct 12, 2017 at 17:20 | history | answered | WhatRoughBeast | CC BY-SA 3.0 |