Hacker News Board Hacker News, browsed like a classic message board
Live data from Hacker News

Why does current flow the opposite way from the electrons?

mathstodon.xyz

Post reply on HN
Print view View original

201–210 of 254 posts

Re: Why does current flow the opposite way from the electrons?

#201

Post by kazinator »

justhadto123094 wrote: post #29
Gibbon1 wrote: post #24

Earlier quoted context omitted.

Anytime electrochemistry is involved it's important. But regular electronics not very much. I think positive and negative mostly trips up people trying to use what they think is happening to explain theory. When it's not that useful most of the time. What I could never keep straight is anode and cathode.

CAThodes are PAWsitve

But if you connect a 5V battery in parallel with a 4V battery, the 5 will try to charge the 4. So the (+) terminal of the 5V battery will act as a cathode, but the (+) terminal of the 4V battery as anode.

"CCD" -> "cathode: current departs"

In chemistry though, cations are positive ions and anions are negative ions.

Re: Why does current flow the opposite way from the electrons?

#202

Post by SoftTalker »

wongarsu wrote: post #189
shepherdjerred wrote: post #173

Earlier quoted context omitted.

I thought that was safe because the voltage/current isn't enough to go through skin or something like that.

For AA batteries that's true. But licking a 9V battery gives you a notable shock. Any wet skin should work to some degree at 9V, but the tongue is very sensitive so it brings the most dramatic effect.

Licking across both terminals? Or licking just one?

Re: Why does current flow the opposite way from the electrons?

#203

Post by RevEng »

luyu_wu wrote: post #60
Am4TIfIsER0ppos wrote: post #15

Electrons were not discovered for more than a hundred years after his death. How could he have done the "right" thing other than by chance?

IMO the issue is that we used his convention even after we realized he was wrong. As a student, this trips me up immeasurably, especially after learning non-symmetric circuits.

We did so because it would have been even more confusing if one day we just switched the meaning. Electricity had been studied for a hundred years by the time we understood electrons as the charge carrier. In the mean time, many formulas were derived and books were written. To flip the meaning of everything would result in mass confusion about which way we were defining current flow. To disambiguate, we would want some unique name to describe one system versus the other. And so we did: we understand a distinction between conventional current flow and electron flow.

Re: Why does current flow the opposite way from the electrons?

#205

Post by oneshtein »

kevin_thibedeau wrote: post #83
xdavidliu wrote: post #27

Earlier quoted context omitted.

how is this recent? This was like 1900.

The Nobel prize for proving the existence of molecules was awarded in 1926. Less than 100 years ago. Our understanding of physical chemistry is extremely recent.

In the absence of firsthand accounts, historical sources become our sole means of understanding past events. This transition typically occurs within two generations, or roughly 50 years, of the event's occurrence.

Re: Why does current flow the opposite way from the electrons?

#207

Post by gus_massa »

marcosdumay wrote: post #132
gus_massa wrote: post #77

Earlier quoted context omitted.

https://en.wikipedia.org/wiki/Hall_effect If you put a magnetic field that is perpendicular to the current, you get a charge in one dide of the wires that depends on the moving charges. This is used to measure magnetic fields. https://en.wikipedia.org/wiki/Vacuum_tube usualy you heat only one electrode, but you must heat the correct one so electrons can jump to the other electrode. https://en.wikipedia.org/wiki/Catho…

> https://en.wikipedia.org/wiki/Transistor IIRC they are also not symetric They kinda are. Solid state conductors have those virtual particles called holes, that represent the global state of "having fewer electrons around here". You can have transistors where the electrons are carrying charge or where holes are. But the properties of holes and electrons are not completely symmetric. Holes disperse each other more st…

I agree, but think you are talking about the differences of the NPN and PNP transistors, but I'm talking about the differences of the emisor and the collector in the same transistor.

In a very naive explanation, you can exchange the emisor and the collector, but in a real cirtuit it is a bad idea. (I'm not sure why. I think it may stil work but it's slower or less efficient, but I'm not sure about the details.)

Re: Why does current flow the opposite way from the electrons?

#208

Post by DidYaWipe »

This is great. I'm glad I'm not the only one this annoyed about the mixed messages in electronics. It really does mess you up as you try to learn and reason about how circuits work, when the first thing you learn in school is that electrons flow from negative to positive.

Re: Why does current flow the opposite way from the electrons?

#209

Post by wruza »

timschmidt wrote: post #99
lazide wrote: post #64

Earlier quoted context omitted.

Was ‘Blue’ invented or discovered? Fundamentally, it’s the same type of problem - and really more of a philosophical thing.

Color perception depends on peculiarities of biology. Numbers and numeric quantities do not. The number of quarks in a proton or neutron is always 3. There are a fair number of dimensionless physical constants: https://en.wikipedia.org/wiki/Dimensionless_physical_constan... You can choose different number systems to represent the values symbolically, but the numbers will always be the same. At least in this universe.…

Interestingly, this argument was weak before we ended up with truly elementary particles. Cause there’s no such thing as three apples or three people. They are unique objects with similarities defined by an observer, and then you go deeper and note that “object” is also a purely synthetic delineation. 3 is a model, not an element of reality. Even advanced maths define it as a set which contains nothing, 1 and 2 (which contains nothing and 1, which contains nothing and is preceded by nothing). Counting and measuring is equivalent to drawing lines — adding something that wasn’t there before.

The fact that particles have identity is also vague, afaiu, so existence of numbers or their non-biological origin is not as easy to prove by example as it seems.

Re: Why does current flow the opposite way from the electrons?

#210

Post by timschmidt »

wruza wrote: post #209
timschmidt wrote: post #99

Earlier quoted context omitted.

Color perception depends on peculiarities of biology. Numbers and numeric quantities do not. The number of quarks in a proton or neutron is always 3. There are a fair number of dimensionless physical constants: https://en.wikipedia.org/wiki/Dimensionless_physical_constan... You can choose different number systems to represent the values symbolically, but the numbers will always be the same. At least in this universe.…

Interestingly, this argument was weak before we ended up with truly elementary particles. Cause there’s no such thing as three apples or three people. They are unique objects with similarities defined by an observer, and then you go deeper and note that “object” is also a purely synthetic delineation. 3 is a model, not an element of reality. Even advanced maths define it as a set which contains nothing, 1 and 2 (whic…

> [sic]Cause there’s no such thing as three apples or three people.

I understand what you're saying. Occurrences like https://en.wikipedia.org/wiki/Ring_species demonstrate that the idea of "species" isn't firm and that what truly matters is each individual and their unique circumstances. But this seems to me to be more a limitation of language and philosophy than a repudiation of math.

As you pointed out, it's all equivalent to drawing tally lines, counting pebbles, sliding counters on an abacus, or counting fingers and toes. Despite the fractal nature of coastlines and the constant exchange of matter and energy between adjacent parts of the universe, it is possible to agree upon useful delineations. And there is not any alternative maths which happens to describe practical observations in a way which does not reduce to the maths with which we are familiar.

Post reply on HN