5 ms·

I got told what electricity is in primary school, in middle school, in high school, and in university. Every time I understood it less. I even watched some vi

by k__ 2y ago

I got told what electricity is in primary school, in middle school, in high school, and in university. Every time I understood it less. I even watched some videos where people interviewed physics professors, to explain what it really is, and the explanations only got more convoluted. Seemingly not because those people were bad at explaining, but because if you want to explain it as correctly as possible, it just isn't intuitive at all.

ekianjo 2y ago
it's confusing because all of the words we use in the field make it seem like it's akin to water flowing (current) whereas the physical phenomenon is far beyond the movements of individual electrons.
- srean 2y ago
  It's not a bad analogy if you also consider the pressure wave. That travels a whole lot faster than the water molecules.
- H8crilA 2y ago
  The problem with (or the advantage of) the water flowing analogy, or even more broadly the discrete element model, is that it explains reality good enough to be used in most practical situations. Schematics are ubiquitous, yes they are "fake", but they are also usually "correct enough". Kind of like the incorrect Bohr's model of electrons orbiting the nucleus actually does explain the emission spectra (up to a point). But there is an accessible video that explains electricity pretty well. Veritasium - The Big Misconception About Electricity: https://www.youtube.com/watch?v=bHIhgxav9LY https://www.youtube.com/watch?v=bHIhgxav9LY There is one commonly used concept that requires understanding electricity correctly, and not just as a combination of waterhoses and gizmos. It's impedance, and it directly corresponds to the "controversial" experiment that Veritasium is proposing in his video. Impedance breaks the pipe-of-electrons analogy.
  - BenjiWiebe 2y ago
    Are you sure we can't explain impedance with the water analogy? You would have to start with alternating current water, since "DC" water maps to DC, where impedance =resistance. Once you've got alternating water, you can add inductance (inertia) and capacitance (rubber diaphragm tanks) and I think it all works out. It's just that we don't have a good intuition for alternating water current so it's not a very useful analogy in that case.
    - Workaccount2 2y ago
      I have gone down this hole many times before and while it is kind of possible (the equations for a capacitor and an inductor are basically just a spring and a flywheel), it just creates really convoluted images that won't fit well (or will be too convoluted) when you try to integrate into wider electronics.
    - _whiteCaps_ 2y ago
      Antennas are sprinklers in the water analogy.
      - TheSpiceIsLife 2y ago
        And when looking at alternating current, all the pipes are kind of leaky?
        H8crilA 2y ago
        Yes, all pipes leak, even DC pipes, in two almost entirely independent ways (electric and magnetic). And the vector product of these leakages (the Poynting vector) is what actually transmits power. Note that this energy transfer happens entirely outside of the conductor. Sounds bizarre, right? That's why this is mostly ignored unless it can't be, for example in very fast circuits.
    - H8crilA 2y ago
      Yes you can keep going a bit further, but that's still the lumped element model. The problem is when you analyze something like a transmission line - like that circuit presented in the video. Or a PCB with very fast signals where you have to understand that the energy moves through the insulator, not through the conductor, or the circuit will not work. One way to look at this is that there is no such thing as a hose for electricity. It cannot be confined to a conductor, even if it is also wrapped by an insulator. It is only mostly confined. And this is not some failure of materials engineering that we may overcome one day, this is just how this stuff works. BTW, the answer in the video is 1/c seconds, i.e. one meter worth of speed of light. And the lightbulb will experience current determined by the impedance of the transmission line. Then the fields will do a full wraparound the ends, at which point the circuit will start stabilizing around the resistance of the load. It can take a few back-and-forth iterations to stabilize the current.
criddell 2y ago
And at each level the degree of confidence seems to be dropping. When you get to the point where the explanation includes an electron being made from a changes in a quantum field and a quantum field is probability, it starts to feel like there’s nothing underpinning reality.
- immibis 2y ago
  Impostor Syndrome.
- B1FF_PSUVM 2y ago
  > it starts to feel like there’s nothing underpinning reality. "Lock it up, they're starting to catch on." ;-)
- mr_toad 2y ago
  > nothing underpinning reality Gravity is a thing, and we can feel it under us. But we can’t touch it, or see it. Intuitively things that we can touch and see should be qualitatively different, but this intuition is wrong. Turns out it’s just big weak fields like gravity, and small strong fields like electromagnetism.
  - yazantapuz 2y ago
    > and we can feel it under us. I think that we don't feel gravity directly, just our atoms resisting being squashed.
- int_19h 2y ago
  "It's all just information" is a valid take on modern physics, with quite a few adherents.
kzrdude 2y ago
AlphaPhoenix's measurements, experiments and visualisations really help! They show some things that are normally not even taught and even electrical engineers will appreciate to see this. This video he made about it is very good, and worth watching if you wonder about how electricity propagates from one end of a conductor to the other. https://www.youtube.com/watch?v=2AXv49dDQJw https://www.youtube.com/watch?v=2AXv49dDQJw
- andrewflnr 2y ago
  He's done a handful of similar videos, and they're all by far the best explanations of electricity I've ever encountered.
- MaXtreeM 2y ago
  Yes, this video and the one before called "An intuitive approach for understanding electricity" are absolutely great.
sky2224 2y ago
Ugh, this is one thing I really hate about academia. There's this weird fixation on trying to make things intuitive or tangible at every step along the way. The result is that you get five hundred very wrong/sort of wrong/okayish explanations that all differ enough to make it so we score the student wrong during examinations anyway because they chose the wrong tutorial to follow. Sometimes, things are just hard to understand. Sooner or later students are going to have to face that, so why do we delay the inevitable?
- sitharus 2y ago
  Because there's a lot you can do with basic knowledge of a subject. Very few people need to know the subatomic behaviour of electromagnetic fields that make electricity work, but all of us need to know that it travels in wires and it can kill you.
  - sky2224 2y ago
    I'm particularly talking about in the context of teaching someone what electrons are and how they behave at the subatomic level. High level overview? Sure, use analogies or models that aren't 100% accurate. But if we're talking about students in a university, then it shouldn't really be an issue to get into the nitty gritty. I see this as well when it comes to teaching programming to freshman CS students. For some reason, we've strayed away from lower level languages like C and don't introduce the low level details until students are quite far into their curriculum. Abstracting away the details just muddies the waters in my opinion.
    - Lanolderen 2y ago
      As a recent graduate who did both since I switched from a very theory first uni to a practice first uni I find starting with a high level language much better. If you're trying to learn "class, method, extends, static, var/Integer/int, interface, abstract, virtual, different exceptions, recursion and loops, etc" having to also learn about memory is not helping and if you try to do basic pointers first it becomes kind of like spell chanting. You just start trying different combinations of * and & until it works. Partially because you're a bit overwhelmed and partially because it seems like useless knowledge. The more I worked the more I started to appreciate subjects like operating systems, algorithms, etc but at the time of doing them they seemed too theoretical since they were way above my practical knowledge and useless to the projects I was doing. "Why would I need to know how to build a file system/compiler/etc? Why in the hell would I ever do that?" The other aspect is that if you start with learning the theoretical side you end up worrying you won't be able to code by the end after a bit. For example you've been there for 2 semesters and while you can talk about low level subjects you've barely done a todo list/calculator/chess. If you start with the more high level things by the third semester you can definitely be working part time. This is from the POV of doing CS to start working as a dev and not do academia.
veunes 2y ago
Yep, that's the paradox of learning: sometimes the more you know, the more you realize you don't know
kamaal 2y ago
>>Seemingly not because those people were bad at explaining, but because if you want to explain it as correctly as possible, it just isn't intuitive at all. Sometimes its a whole lot easier to speak the truth than to speak in analogies.

by k__ 2y ago

ekianjo 2y ago

it's confusing because all of the words we use in the field make it seem like it's akin to water flowing (current) whereas the physical phenomenon is far beyond the movements of individual electrons.

srean 2y ago
It's not a bad analogy if you also consider the pressure wave. That travels a whole lot faster than the water molecules.
H8crilA 2y ago
The problem with (or the advantage of) the water flowing analogy, or even more broadly the discrete element model, is that it explains reality good enough to be used in most practical situations. Schematics are ubiquitous, yes they are "fake", but they are also usually "correct enough". Kind of like the incorrect Bohr's model of electrons orbiting the nucleus actually does explain the emission spectra (up to a point). But there is an accessible video that explains electricity pretty well. Veritasium - The Big Misconception About Electricity: https://www.youtube.com/watch?v=bHIhgxav9LY https://www.youtube.com/watch?v=bHIhgxav9LY There is one commonly used concept that requires understanding electricity correctly, and not just as a combination of waterhoses and gizmos. It's impedance, and it directly corresponds to the "controversial" experiment that Veritasium is proposing in his video. Impedance breaks the pipe-of-electrons analogy.
- BenjiWiebe 2y ago
  Are you sure we can't explain impedance with the water analogy? You would have to start with alternating current water, since "DC" water maps to DC, where impedance =resistance. Once you've got alternating water, you can add inductance (inertia) and capacitance (rubber diaphragm tanks) and I think it all works out. It's just that we don't have a good intuition for alternating water current so it's not a very useful analogy in that case.
  - Workaccount2 2y ago
    I have gone down this hole many times before and while it is kind of possible (the equations for a capacitor and an inductor are basically just a spring and a flywheel), it just creates really convoluted images that won't fit well (or will be too convoluted) when you try to integrate into wider electronics.
  - _whiteCaps_ 2y ago
    Antennas are sprinklers in the water analogy.
    - TheSpiceIsLife 2y ago
      And when looking at alternating current, all the pipes are kind of leaky?
      - H8crilA 2y ago
        Yes, all pipes leak, even DC pipes, in two almost entirely independent ways (electric and magnetic). And the vector product of these leakages (the Poynting vector) is what actually transmits power. Note that this energy transfer happens entirely outside of the conductor. Sounds bizarre, right? That's why this is mostly ignored unless it can't be, for example in very fast circuits.
  - H8crilA 2y ago
    Yes you can keep going a bit further, but that's still the lumped element model. The problem is when you analyze something like a transmission line - like that circuit presented in the video. Or a PCB with very fast signals where you have to understand that the energy moves through the insulator, not through the conductor, or the circuit will not work. One way to look at this is that there is no such thing as a hose for electricity. It cannot be confined to a conductor, even if it is also wrapped by an insulator. It is only mostly confined. And this is not some failure of materials engineering that we may overcome one day, this is just how this stuff works. BTW, the answer in the video is 1/c seconds, i.e. one meter worth of speed of light. And the lightbulb will experience current determined by the impedance of the transmission line. Then the fields will do a full wraparound the ends, at which point the circuit will start stabilizing around the resistance of the load. It can take a few back-and-forth iterations to stabilize the current.

criddell 2y ago

And at each level the degree of confidence seems to be dropping. When you get to the point where the explanation includes an electron being made from a changes in a quantum field and a quantum field is probability, it starts to feel like there’s nothing underpinning reality.

immibis 2y ago
Impostor Syndrome.
B1FF_PSUVM 2y ago
> it starts to feel like there’s nothing underpinning reality. "Lock it up, they're starting to catch on." ;-)
mr_toad 2y ago
> nothing underpinning reality Gravity is a thing, and we can feel it under us. But we can’t touch it, or see it. Intuitively things that we can touch and see should be qualitatively different, but this intuition is wrong. Turns out it’s just big weak fields like gravity, and small strong fields like electromagnetism.
- yazantapuz 2y ago
  > and we can feel it under us. I think that we don't feel gravity directly, just our atoms resisting being squashed.
int_19h 2y ago
"It's all just information" is a valid take on modern physics, with quite a few adherents.

kzrdude 2y ago

AlphaPhoenix's measurements, experiments and visualisations really help! They show some things that are normally not even taught and even electrical engineers will appreciate to see this. This video he made about it is very good, and worth watching if you wonder about how electricity propagates from one end of a conductor to the other. https://www.youtube.com/watch?v=2AXv49dDQJw https://www.youtube.com/watch?v=2AXv49dDQJw

andrewflnr 2y ago
He's done a handful of similar videos, and they're all by far the best explanations of electricity I've ever encountered.
MaXtreeM 2y ago
Yes, this video and the one before called "An intuitive approach for understanding electricity" are absolutely great.

sky2224 2y ago

Ugh, this is one thing I really hate about academia. There's this weird fixation on trying to make things intuitive or tangible at every step along the way. The result is that you get five hundred very wrong/sort of wrong/okayish explanations that all differ enough to make it so we score the student wrong during examinations anyway because they chose the wrong tutorial to follow. Sometimes, things are just hard to understand. Sooner or later students are going to have to face that, so why do we delay the inevitable?

sitharus 2y ago
Because there's a lot you can do with basic knowledge of a subject. Very few people need to know the subatomic behaviour of electromagnetic fields that make electricity work, but all of us need to know that it travels in wires and it can kill you.
- sky2224 2y ago
  I'm particularly talking about in the context of teaching someone what electrons are and how they behave at the subatomic level. High level overview? Sure, use analogies or models that aren't 100% accurate. But if we're talking about students in a university, then it shouldn't really be an issue to get into the nitty gritty. I see this as well when it comes to teaching programming to freshman CS students. For some reason, we've strayed away from lower level languages like C and don't introduce the low level details until students are quite far into their curriculum. Abstracting away the details just muddies the waters in my opinion.
  - Lanolderen 2y ago
    As a recent graduate who did both since I switched from a very theory first uni to a practice first uni I find starting with a high level language much better. If you're trying to learn "class, method, extends, static, var/Integer/int, interface, abstract, virtual, different exceptions, recursion and loops, etc" having to also learn about memory is not helping and if you try to do basic pointers first it becomes kind of like spell chanting. You just start trying different combinations of * and & until it works. Partially because you're a bit overwhelmed and partially because it seems like useless knowledge. The more I worked the more I started to appreciate subjects like operating systems, algorithms, etc but at the time of doing them they seemed too theoretical since they were way above my practical knowledge and useless to the projects I was doing. "Why would I need to know how to build a file system/compiler/etc? Why in the hell would I ever do that?" The other aspect is that if you start with learning the theoretical side you end up worrying you won't be able to code by the end after a bit. For example you've been there for 2 semesters and while you can talk about low level subjects you've barely done a todo list/calculator/chess. If you start with the more high level things by the third semester you can definitely be working part time. This is from the POV of doing CS to start working as a dev and not do academia.

veunes 2y ago

Yep, that's the paradox of learning: sometimes the more you know, the more you realize you don't know

kamaal 2y ago

>>Seemingly not because those people were bad at explaining, but because if you want to explain it as correctly as possible, it just isn't intuitive at all. Sometimes its a whole lot easier to speak the truth than to speak in analogies.