Ben's Battery

[BillyJoe]

Why is it "WRONG"?

The negatively charged electrons exit from the negative terminal.
Sounds okay to me.

Anyone?

thanks,
BillyJoe

PS: My welcome message tells me I last entered the forum on 16th Dec! Has it really been that long? (I've kept reading the Commentary though.)

 

[to.by]

Who says it is wrong. Seems all right to me, apart from some redundancy: electrons do have a negative charge, otherwise they're positrons.

 

[MRC_Hans]

The reason we label elelctron negatively charged is that they emerge from the negative terminal. Obviously, the terms "positive" and "negative" are entirely arbitrary, here. We might as well call them "red" and "fish".

The old flaw in electric theory is that electric current was assumed to be something that ran from the positive terminal to the negative, not the names of the poles. I'm not sure it was Ben Franklin's idea, however; I think the idea originated back with Volta, who made the first battery (in historic time, at least, there are those things in Bagdad). He resolved that a current of something flowed from the copper plate to the zinc plate in his battery, and this was presumably because he happend to have the copper plate on top.

Hans

 

[BillyJoe]

toby,

Who says it is wrong.

Randi, in this weeks commentary.

Seems all right to me, apart from some redundancy: electrons do have a negative charge, otherwise they're positrons.

Is that true - that positrons are electrons with positive charge?

BJ

 

[BillyJoe]

The reason we label electrons negatively charged is that they emerge from the negative terminal.

I see.
So, if Ben (or Volta) had labelled that terminal as "positive", the charge of an electron would have been called "positive"?

Obviously, the terms "positive" and "negative" are entirely arbitrary, here. We might as well call them "red" and "fish".

Presumably that red fish is a certain type of eel

The old flaw in electric theory is that electric current was assumed to be something that ran from the positive terminal to the negative, not the names of the poles.

So RANDI is wrong then?

thanks,
BillyJoe

 

[Orthoptera]

I think the idea is that the side with a surplus of electrons (which we label -) would logically flow towards the side with fewer (which we label +), but Franklin didn't understand the mechanism and so guessed "wrong". Kind of like calling water at the top of a hill "Low Water".

 

[Darat]

The reason we label elelctron negatively charged is that they emerge from the negative terminal. Obviously, the terms "positive" and "negative" are entirely arbitrary, here. We might as well call them "red" and "fish".

The old flaw in electric theory is that electric current was assumed to be something that ran from the positive terminal to the negative, not the names of the poles. I'm not sure it was Ben Franklin's idea, however; I think the idea originated back with Volta, who made the first battery (in historic time, at least, there are those things in Bagdad). He resolved that a current of something flowed from the copper plate to the zinc plate in his battery, and this was presumably because he happend to have the copper plate on top.

Hans

I think at Franklin's time electrical effects (i.e. electricity being able to repulse as well as attract) were being explained by hypotheses that electricity consisted of a fluid or hypothesis that it consisted of two fluids. (This is why even today we still talk of electricity flowing!). Franklin explained the apparent contradictory properties of electricity using the idea of there just being one fluid.

 

[Freethinker]

Indeed, the electrons do exit from the negative terminal, so current flows from negative to positive. However, it was wrongly assumed that current flowed from positive to negative, and the negative electron charge made it look that way. Electrical convention today treats electricity as if it were the flow of positively charged particles from the positive terminal.

 

[MRC_Hans]

I see.
So, if Ben (or Volta) had labelled that terminal as "positive", the charge of an electron would have been called "positive"?

Presumably that red fish is a certain type of eel

So RANDI is wrong then?

thanks,
BillyJoe

Yes.

Electric eel?

Yes, or at least imprecise.

Hans

 

[MRC_Hans]

Indeed, the electrons do exit from the negative terminal, so current flows from negative to positive. However, it was wrongly assumed that current flowed from positive to negative, and the negative electron charge made it look that way. Electrical convention today treats electricity as if it were the flow of positively charged particles from the positive terminal.

Mmm, yes, if you are a scientist. If you are an electronic mechanic, however, you treat it as a flow of negative charges from minus to plus. So watch out for signs in formulas .

Actually, it is even more tricky. While by far the majority of electronic currents do consist of electrons, it is not them all. Positrons have already been mentioned (they are the antimatter counterpart of electrons), but a current can also consist of positive ions, and in (P doped) semiconductor crystals, we have "holes", which are really missing electrons, and thus act as positive charges (and move from plus to minus).

Hans

 

[Freethinker]

Mmm, yes, if you are a scientist. If you are an electronic mechanic, however, you treat it as a flow of negative charges from minus to plus. So watch out for signs in formulas .

Physicists are the only ones I know who treat electricity as it really behaves. Electrical engineers (which I am)use the positive current flow convention except at the semiconductor substrate level where the holes become a signicant enough factor that they must be considered.

 

[BillyJoe]

So, let's get this straight......

Randi was wrong when he said Ben was wrong because he was right, except for the wrong reason, which sort of makes Randi right, except that it wasn't Ben, which makes Randi wrong again.

Right?



BillyJoe

 

[MRC_Hans]

No: Randi was wrong about Ben, who was right about Volta, who was wrong, but for the right reason, which means Randi was rightly wrong, which is his right, like anybody else.

Hans

 

[Jellby]

I guess that, if electric charges were defined today, we would give the electron a positive charge, because it's usually the charge considered as "elementary", because it's the main responsible of electric current... It makes sense to have the basic unit a positive one. In this sense the original Ben Franklin's labelling was "wrong". Not that it's really wrong, but he would probably have liked it the other way. At least that's how I read it.

If I remember correctly, something similar happened when Fischer assigned the absolute configuration of glucose. But this time he was right. From http://www.cem.msu.edu/~reusch/VirtualText/carbhyd.htm :

At the time Fischer undertook the glucose project it was not possible to establish the absolute configuration of an enantiomer. Consequently, Fischer made an arbitrary choice for (+)-glucose and established a network of related aldose configurations that he called the D-family. [...] Fischer's initial assignment of the D-configuration had a 50:50 chance of being right [...] In 1951 x-ray fluorescence studies of (+)-tartaric acid, carried out in the Netherlands, proved that Fischer's choice was correct.

 

[luchog]

Mmm, yes, if you are a scientist. If you are an electronic mechanic, however, you treat it as a flow of negative charges from minus to plus. So watch out for signs in formulas .

Actually, it is even more tricky. While by far the majority of electronic currents do consist of electrons, it is not them all. Positrons have already been mentioned (they are the antimatter counterpart of electrons), but a current can also consist of positive ions, and in (P doped) semiconductor crystals, we have "holes", which are really missing electrons, and thus act as positive charges (and move from plus to minus).

Unfortunately, in Electrical Engineering, there is still a holdover from the old tradition of positive-to-negative; so you'll occasionally hear EEs talking about ridiculous fictions like "hole flow" when designing circuits.

 

[bjb]

Long ago, current flow was defined as the transfer of positive charge carriers. Using this definition, current always flows from positive to negative. Benjamin Franklin's designation of the battery terminal polarity is still correct as long as we define electricity as *current flow*. Once electrons were shown to be the charge carriers and that they had a 'negative' charge, the term 'electron flow' came into use. Electron flow is opposite to current flow, and it always flows from negative to positive.

But within an electrochemical battery, current flows because charge carries are migrating to both battery terminals. In a battery, electrons are *not* the charge carriers. Positively and negatively charged ions are moving through the battery electrolyte and in opposite directions. It is entirely correct to say that 'electricity' is moving from the + terminal to the - terminal *and* from - to +, both at the same time. Charge carriers are moving in two directions at once, so to avoid confusion, the convention that *current* flows from + to - is still needed.

 

[BillyJoe]

....who was wrong, but for the right reason...

It is easy to see how you can be right for the wrong reason, but I didn't immediately understand how you can be "wrong, but for the right reason".

But you do make sense

I guess what he intended to do was to label the terminals according to the direction the current flows. This is the right reason. But he simply assumed that the current was flowing from top to bottom in his experimental setup. But he was wrong in that assumption.

Hope that clears everyone else up as well.


BillyJoe

 

[BillyJoe]

Jellby,

I guess that, if electric charges were defined today, we would give the electron a positive charge....

.....and reverse the names of the terminals. Agreed?

...because it's usually the charge considered as "elementary", because it's the main responsible of electric current... It makes sense to have the basic unit a positive one.

Sounds good to me.

In this sense the original Ben Franklin's labelling was "wrong".

Yes.

Not that it's really wrong, but he would probably have liked it the other way. At least that's how I read it.

No, he was really wrong. He thought the current was flowing the other way.


At least that's my take,
BJ

 

[BillyJoe]

bjb,

Long ago, current flow was defined as the transfer of positive charge carriers. Using this definition, current always flows from positive to negative. Benjamin Franklin's designation of the battery terminal polarity is still correct as long as we define electricity as *current flow*. Once electrons were shown to be the charge carriers and that they had a 'negative' charge, the term 'electron flow' came into use. Electron flow is opposite to current flow, and it always flows from negative to positive..

Now you ARE a naughty boy aren't you? Please pay attention and listen carefully, because you have missed the point entirely....

But seriously...the electrons were said to be negatively charged BECAUSE of the (wrong) way the terminals were named. If they were labelled correctly, the electrons would be said to be positively charged.

But within an electrochemical battery, current flows because charge carries are migrating to both battery terminals. In a battery, electrons are *not* the charge carriers. Positively and negatively charged ions are moving through the battery electrolyte and in opposite directions. It is entirely correct to say that 'electricity' is moving from the + terminal to the - terminal *and* from - to +, both at the same time. Charge carriers are moving in two directions at once, so to avoid confusion, the convention that *current* flows from + to - is still needed.

I take it all back! You do make sense.
(That's not to say you weren't not incorrect before though)


BJ