4 ms·

My favorite thing about electrical theory is that all this business about flow of energy going from + to - is the idea of "electron holes" flowing, instead of t

by ok_dad 2y ago

My favorite thing about electrical theory is that all this business about flow of energy going from + to - is the idea of "electron holes" flowing, instead of the actual electrons! Basically all of electronics and electricity uses hole flow convention. It seems weird to me we don't use electron-flow convention (aka: reality), but then again I'm a weird guy.

snailmailstare 2y ago
I had a similarly funny discussion with a proper engineering student on refrigeration insulation and why it isn't more natural to express it similarly with temporarily trapping cold given the inevitable nature of heat/entropy.
- criddell 2y ago
  I remember when I was very young I asked my dad if a refrigerator works by moving cold into the box or heat out of the box and he told me it was the latter. It’s a strong memory because he also said something to the effect of that being a good question and at that age, comments like that had an impact on me.
jeffwass 2y ago
But that’s because of historical precedent, if you weren’t aware of this then congrats for being one of today’s lucky 10,000! Ben Franklin arbitrarily picked the positive anode as the starting point when coming up with the idea of electricity flowing, long before we had any understanding of atomic theory. It wouldn’t make sense to just invert everything after we discovered that electrons are the actual fundamental charge carriers.
ysofunny 2y ago
It seems to me like it's an artifact of how it was all discovered and initially implemented. like scientists didn't realize electrons were flowing in the opposite direction, but engineers already had working electrical devices
at_a_remove 2y ago
I have expressed this repeatedly: the assignation of a negative value to the electron and a positive value to the proton has probably slowed humanity by a decade.
- dotancohen 2y ago
  Anybody who needs to know this detail to design or repair a device, already knows it. There are no simple enough devices where this is relevant for casual repair or modification. You can fix your DC devices such as cellphones and your AC appliances such as refrigerators, and even design your own phones and refrigerators, without knowing in which direction the fundamental particles flow.
- srean 2y ago
  Could you give one example
  - at_a_remove 2y ago
    In terms of pedagogy, it is a problem. I started tutoring other kids in grade school and eventually got paid for it as a side gig later in life. If I ended up covering electronics and/or general electricity, I saw the same thing I saw as an undergrad taking EE courses: confusion. A lot of people found the situation counter-intuitive. It required extra mental labor for them. Hence, multiplied against millions of people, there's overall lost time. And this isn't just in young people, either. Knew a guy who swore up and down that the "electron holes" really represent positrons. Bad notation, weird syntax, poor choices in variable names, and so on, all of these are a collective drag which could be streamlined away.
    - srean 2y ago
      Seems a pretty trivial change, like, hot water's on the left tap not the right tap. Humans are more than capable of handling that minor conceptual change. Life routinely throws far more challenging changes to adopt to. Nothing fundamentally changes because of Franklin's incorrect guess. The postit sticker goes "there " instead of "here" kind of a thing. Certainly not as grandiose and melodramatic as putting humanity back by a decade.
card_zero 2y ago
The terms are due to Ben Franklin: We say B is electrised positively; A negatively: or rather B is electrised plus and A minus ... These terms we may use until your philosophers give us better. Here A and B are Franklin's buddies, standing on insulating plates while one of them rubs a glass tube with a piece of, if I remember rightly (can't find the proper source), "buckskin". Then they reach out to join hands and a spark crosses the gap. Problem is, it isn't even clear from the experiment which of A and B really was negatively charged, because it turns out the charge depends on the nature of the "buckskin" (or whatever term he used), and how hairy, furry, or possibly even leathery it was. The resulting charge could be positive or negative, depending. So he defined the terms, but didn't even clearly assign them to direction of electron flow. Edit: the ambiguity is shown in this picture: https://en.wikipedia.org/wiki/Triboelectric_effect#/media/File:Triboelectric-series_EN.svg https://en.wikipedia.org/wiki/Triboelectric_effect#/media/Fi... Here leather is above glass, and fur is below it. He was definitely rubbing glass with something like leather or fur, but the resulting charge depends on where in the series that thing was relative to glass.
- saghm 2y ago
  As usual, xkcd has a relevant comic about this: https://xkcd.com/567/ https://xkcd.com/567/
  - 3eb7988a1663 2y ago
    This makes the robot apocalypse happen at an increased rate. All the advancements made without this stupid error infecting everything.
  - card_zero 2y ago
    Found it from the horse's mouth, finally: "We rub our tubes with buckſkin". https://archive.org/details/experimentsobser00fran_0/page/17/mode/1up?q=%22We+rub+our+tubes+with%22 https://archive.org/details/experimentsobser00fran_0/page/17... Don't know where Randall get "silk" from.
    - ThrowawayTestr 2y ago
kqr 2y ago
> about flow of energy going from + to - is the idea of "electron holes" flowing You mean flow of charge. My favourite thing about electricity is how the actual energy is transferred on the outside of the wires, in both the directions of positive and negative charge. Resistance is the portion of the energy that accidentally enters the wire. The energy flux inside the wires -- and on the surface of the wires -- is zero. Just outside their surface it is very high. A capacitor wouldn't work if the energy came from its poles. No, the energy used to charge it enters from the side. This is so counter-intuitive!
- benterix 2y ago
  > accidentally Well, we may see it this way, but there's nothing accidental in it, it's juts an inherent property of every conductor (except superconductors).
- marcosdumay 2y ago
  Charge flows on the same medium as energy. There's current on the equation of electrical power for a reason. That bullshit model about electricity flowing around the wires is good for generating Youtube engagement, but it doesn't represent the actual physics, makes things impossible to calculate, doesn't lead to any intuitive understanding, and makes things impossible to learn. Or, in other words, the model is bullshit. DC current flows entirely in the wires (up to at least "parts per billion" precision), as does energy, because energy flows at the same place current flows. AC current leaks. Everybody knows that, how it leaks is well known, and there are plenty of resources to calculate almost everything around it.
  - jmb99 2y ago
    Exactly. If energy flowed around the wires and resistance was “the portion of the energy that accidentally entered the wire” then larger wires would have larger resistance (due to a higher chance of “stray energy entering the wire”) than smaller wires, which is clearly incorrect. It really is a terrible model in almost every way.
    - 2y ago
choxi 2y ago
It’s weird in semiconductor physics too because the electrons flow uphill through voltage potentials
veunes 2y ago
And it's wild for me that we've been teaching it this way for so long just because of a historical guess made before electrons were even discovered

by ok_dad 2y ago

snailmailstare 2y ago

I had a similarly funny discussion with a proper engineering student on refrigeration insulation and why it isn't more natural to express it similarly with temporarily trapping cold given the inevitable nature of heat/entropy.

criddell 2y ago
I remember when I was very young I asked my dad if a refrigerator works by moving cold into the box or heat out of the box and he told me it was the latter. It’s a strong memory because he also said something to the effect of that being a good question and at that age, comments like that had an impact on me.

jeffwass 2y ago

But that’s because of historical precedent, if you weren’t aware of this then congrats for being one of today’s lucky 10,000! Ben Franklin arbitrarily picked the positive anode as the starting point when coming up with the idea of electricity flowing, long before we had any understanding of atomic theory. It wouldn’t make sense to just invert everything after we discovered that electrons are the actual fundamental charge carriers.

ysofunny 2y ago

It seems to me like it's an artifact of how it was all discovered and initially implemented. like scientists didn't realize electrons were flowing in the opposite direction, but engineers already had working electrical devices

at_a_remove 2y ago

I have expressed this repeatedly: the assignation of a negative value to the electron and a positive value to the proton has probably slowed humanity by a decade.

dotancohen 2y ago
Anybody who needs to know this detail to design or repair a device, already knows it. There are no simple enough devices where this is relevant for casual repair or modification. You can fix your DC devices such as cellphones and your AC appliances such as refrigerators, and even design your own phones and refrigerators, without knowing in which direction the fundamental particles flow.
srean 2y ago
Could you give one example
- at_a_remove 2y ago
  In terms of pedagogy, it is a problem. I started tutoring other kids in grade school and eventually got paid for it as a side gig later in life. If I ended up covering electronics and/or general electricity, I saw the same thing I saw as an undergrad taking EE courses: confusion. A lot of people found the situation counter-intuitive. It required extra mental labor for them. Hence, multiplied against millions of people, there's overall lost time. And this isn't just in young people, either. Knew a guy who swore up and down that the "electron holes" really represent positrons. Bad notation, weird syntax, poor choices in variable names, and so on, all of these are a collective drag which could be streamlined away.
  - srean 2y ago
    Seems a pretty trivial change, like, hot water's on the left tap not the right tap. Humans are more than capable of handling that minor conceptual change. Life routinely throws far more challenging changes to adopt to. Nothing fundamentally changes because of Franklin's incorrect guess. The postit sticker goes "there " instead of "here" kind of a thing. Certainly not as grandiose and melodramatic as putting humanity back by a decade.

card_zero 2y ago

The terms are due to Ben Franklin: We say B is electrised positively; A negatively: or rather B is electrised plus and A minus ... These terms we may use until your philosophers give us better. Here A and B are Franklin's buddies, standing on insulating plates while one of them rubs a glass tube with a piece of, if I remember rightly (can't find the proper source), "buckskin". Then they reach out to join hands and a spark crosses the gap. Problem is, it isn't even clear from the experiment which of A and B really was negatively charged, because it turns out the charge depends on the nature of the "buckskin" (or whatever term he used), and how hairy, furry, or possibly even leathery it was. The resulting charge could be positive or negative, depending. So he defined the terms, but didn't even clearly assign them to direction of electron flow. Edit: the ambiguity is shown in this picture: https://en.wikipedia.org/wiki/Triboelectric_effect#/media/File:Triboelectric-series_EN.svg https://en.wikipedia.org/wiki/Triboelectric_effect#/media/Fi... Here leather is above glass, and fur is below it. He was definitely rubbing glass with something like leather or fur, but the resulting charge depends on where in the series that thing was relative to glass.

saghm 2y ago
As usual, xkcd has a relevant comic about this: https://xkcd.com/567/ https://xkcd.com/567/
- 3eb7988a1663 2y ago
  This makes the robot apocalypse happen at an increased rate. All the advancements made without this stupid error infecting everything.
- card_zero 2y ago
  Found it from the horse's mouth, finally: "We rub our tubes with buckſkin". https://archive.org/details/experimentsobser00fran_0/page/17/mode/1up?q=%22We+rub+our+tubes+with%22 https://archive.org/details/experimentsobser00fran_0/page/17... Don't know where Randall get "silk" from.
  - ThrowawayTestr 2y ago

kqr 2y ago

> about flow of energy going from + to - is the idea of "electron holes" flowing You mean flow of charge. My favourite thing about electricity is how the actual energy is transferred on the outside of the wires, in both the directions of positive and negative charge. Resistance is the portion of the energy that accidentally enters the wire. The energy flux inside the wires -- and on the surface of the wires -- is zero. Just outside their surface it is very high. A capacitor wouldn't work if the energy came from its poles. No, the energy used to charge it enters from the side. This is so counter-intuitive!

benterix 2y ago
> accidentally Well, we may see it this way, but there's nothing accidental in it, it's juts an inherent property of every conductor (except superconductors).
marcosdumay 2y ago
Charge flows on the same medium as energy. There's current on the equation of electrical power for a reason. That bullshit model about electricity flowing around the wires is good for generating Youtube engagement, but it doesn't represent the actual physics, makes things impossible to calculate, doesn't lead to any intuitive understanding, and makes things impossible to learn. Or, in other words, the model is bullshit. DC current flows entirely in the wires (up to at least "parts per billion" precision), as does energy, because energy flows at the same place current flows. AC current leaks. Everybody knows that, how it leaks is well known, and there are plenty of resources to calculate almost everything around it.
- jmb99 2y ago
  Exactly. If energy flowed around the wires and resistance was “the portion of the energy that accidentally entered the wire” then larger wires would have larger resistance (due to a higher chance of “stray energy entering the wire”) than smaller wires, which is clearly incorrect. It really is a terrible model in almost every way.
  - 2y ago

choxi 2y ago

It’s weird in semiconductor physics too because the electrons flow uphill through voltage potentials

veunes 2y ago

And it's wild for me that we've been teaching it this way for so long just because of a historical guess made before electrons were even discovered