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Why does current flow the opposite way from the electrons?

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

#191

Post by afiori »

adrian_b wrote: post #125
throwway120385 wrote: post #13

Because he didn't know anything about electrons, and the experiment he did involving rubbing amber and glass rods on fur and silk cloth only showed that something was transferred between the two materials, and that when the material containing the substance was brought near to the other material containing the other substance, the property conferred by the substances appeared to negate. If you read Teaching Introduct…

The reason why which charge is named positive and which is named negative does not matter is because in all the equations that relate electric charge with other measurable physical quantities we never have an electric charge alone, but we always have the product of two electric charges. The value of the product of two electric charges is invariant to the convention chosen for the sign of the electric charge. Numbers…

There is a way in that it matters: in a vacuum tube you can have cathodic rays but (pragmatically) not anodic rays.

IIRC a Veritasium video claims that these where essentially discovered by mistake in lightbulbs, so I suspect that Franklin would have had a hard time finding them...

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

#192

Post by afiori »

bithive123 wrote: post #165
adrian_b wrote: post #125

Earlier quoted context omitted.

The reason why which charge is named positive and which is named negative does not matter is because in all the equations that relate electric charge with other measurable physical quantities we never have an electric charge alone, but we always have the product of two electric charges. The value of the product of two electric charges is invariant to the convention chosen for the sign of the electric charge. Numbers…

Negation, being a concept, exists only in the mind. Same with "things". A thing is a noun; a part of speech. The "real world" is undifferentiated quanta.

I have an hard time coming to terms with this platonic view of the mind, as if our minds where some kind of extradimensional aliens playing with this sandbox of "undifferentiated quanta" sometime called reality.

I understand how it make sense saying that the concept of spedrunning is completely absent in Ocarina Of Time and only exists in the player playing the game, but I do not see how this would be a good philosophy to apply to ourselves.

I confess that I have a particular aversion to this specific philosophy/POV because I feel like it is riding on the respectability and "coolness" of science to sound more serious while being just another metaphysics without (IMHO) any* particularly good qualities.

* Ok, I admit that it has at least a good quality: it is a good example of a non-religious metaphysics to give to people that cannot imagine a non-religious metaphysics.

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

#194

Post by kazinator »

afiori wrote: post #191
adrian_b wrote: post #125

Earlier quoted context omitted.

The reason why which charge is named positive and which is named negative does not matter is because in all the equations that relate electric charge with other measurable physical quantities we never have an electric charge alone, but we always have the product of two electric charges. The value of the product of two electric charges is invariant to the convention chosen for the sign of the electric charge. Numbers…

There is a way in that it matters: in a vacuum tube you can have cathodic rays but (pragmatically) not anodic rays. IIRC a Veritasium video claims that these where essentially discovered by mistake in lightbulbs, so I suspect that Franklin would have had a hard time finding them...

But a cathode is that terminal of the device where positive current escapes!

It's only a "cathode ray" because it's reversed inside the tube: the terminal where positive current comes out of the device is where the negative current emanates internally to go to the other terminal.

An electron beam shooting out of a device is an anode ray.

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

#195

Post by [deleted] »

throwway120385 wrote: post #13

Because he didn't know anything about electrons, and the experiment he did involving rubbing amber and glass rods on fur and silk cloth only showed that something was transferred between the two materials, and that when the material containing the substance was brought near to the other material containing the other substance, the property conferred by the substances appeared to negate. If you read Teaching Introduct…

[deleted]

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

#196

Post by dotnet00 »

im3w1l wrote: post #133
dotnet00 wrote: post #110

Earlier quoted context omitted.

I think they don't mean it in the literal "you physically can't tell the direction of charge at all" sense. As you say, the very fact that we know the real direction counters that. They mean that within the abstract context of electronics presented in introductory physics, the real direction of charge doesn't matter and cannot be determined. As long as you pick one consistent convention and stick to it, the math will…

I think there might be a difference. From our experience with air we know that blowing and sucking are not quite the same. Blown air has a much greater capacity for direction than sucked air. I would assume that this is because the when we blow we add additional molecules and we get to decide the inertia of those molecules, but when we suck we take away molecules and they have the inertia they have. I would suspect t…

I wouldn't consider the working of an electron gun to be an introductory physics context.

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

#197

Post by kazinator »

adrian_b wrote: post #125
throwway120385 wrote: post #13

Because he didn't know anything about electrons, and the experiment he did involving rubbing amber and glass rods on fur and silk cloth only showed that something was transferred between the two materials, and that when the material containing the substance was brought near to the other material containing the other substance, the property conferred by the substances appeared to negate. If you read Teaching Introduct…

The reason why which charge is named positive and which is named negative does not matter is because in all the equations that relate electric charge with other measurable physical quantities we never have an electric charge alone, but we always have the product of two electric charges. The value of the product of two electric charges is invariant to the convention chosen for the sign of the electric charge. Numbers…

It didn't matter in Franklin's time, but it came to matter later, due to the discovery or invention of devices in which it matters which charge carrier is moving.

For example, in naming the parts of a NPN bipolar junction transistor, the negatively connected terminal is the "emitter", and the positive one the "collector". The base-emitter diode arrow points toward the emitter.

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

#198

Post by [deleted] »

bithive123 wrote: post #165
adrian_b wrote: post #125

Earlier quoted context omitted.

The reason why which charge is named positive and which is named negative does not matter is because in all the equations that relate electric charge with other measurable physical quantities we never have an electric charge alone, but we always have the product of two electric charges. The value of the product of two electric charges is invariant to the convention chosen for the sign of the electric charge. Numbers…

Negation, being a concept, exists only in the mind. Same with "things". A thing is a noun; a part of speech. The "real world" is undifferentiated quanta.

[deleted]

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

#199

Post by kazinator »

joquarky wrote: post #169
bithive123 wrote: post #165

Earlier quoted context omitted.

Negation, being a concept, exists only in the mind. Same with "things". A thing is a noun; a part of speech. The "real world" is undifferentiated quanta.

Put simply, "the map is not the territory"

It would be a bad convention for a map to use valleys to represent mountains.

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

#200

Post by kazinator »

lukeasrodgers wrote: post #106
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.

It doesn't help that very many explanations on the web of anode/cathode are wrong, or at least misleading, and only cover catalytic or galvanic cells. I believe https://chemistry.stackexchange.com/questions/16785/positive... is correct.

The terms "anode* and cathode have their own problems. The cathode is that terminal of a device where positive current emanates. The (+) terminal of a batter is normally a cathode, but when the battery is being charged, it becomes an anode.

The terms anode and cathode should be burned. We don't use them much in modern electronics. E.g. we don't say that the positive power pins of a CPU are anodes, or that ground pins are cathodes.

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