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Old 16th July 2011, 05:39 AM   #101
wbeaty is offline wbeaty  United States
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Originally Posted by DF96 View Post
And I never said that either. You need to read exactly what I said.
Sorry, I responded because you said the following (when we were defining electricity as charge, and for clarity I've substituted the definitions):
"The fact that charge is not gained or lost is perfectly consistent with charge being a form of energy."
See how I read that? When I saw what you'd written, I simply stopped reading. I decided that you must have zero training or knowledge in any sort of physics whatsoever. Seriously arguing that, because charge is conserved, therefore charge could be a form of energy? And saying that I'm wrong because I didn't consider this?

Don't you see a problem there?

Sheesh.

Next you said this below (still with "electricity" meaning "charge," and again I've swapped the words in. That way you can see how I've been reading this all along.)
"You said that charge could not be a form of energy because it is conserved. I tried, but obviously failed, to point out that such conservation would be a requirement if charge is a form of energy."
See the problem? CHARGE ISN'T ENERGY. You're trying to start arguments about charge being energy. In addition my point was that charge flows through a battery without any being gained, so obviously charge is not energy. This whole exchange was just unbelievably stupid. And then you say you're a physicist?!! WTF

But maybe the actual problem here is that you weren't really defining "Electricity" as meaning charge, and were still defining it to mean some fuzzy energy/charge/joulecoulombs thing. In your quotes above, replace "charge" with "electricity" again. See what happens? But that's not what I was seeing. I was seeing the word "charge" in all instances.


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Of course, who I am is irrelevant to the discussion so I probably should not have mentioned it. Truth is truth, whoever says it.
Actually I suspect that training and experience can make a big difference in most fields.

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Old 16th July 2011, 05:51 AM   #102
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Originally Posted by wbeaty View Post
But maybe the actual problem here is that you weren't really defining "Electricity" as meaning charge, and were still defining it to mean some fuzzy energy/charge/joulecoulombs thing.
Or as seems more likely, he wasn't 'defining' it at all but rather using it as a placeholder for something flexible, according to the context in which he found himself. 'A rose by any other name would smell as sweet'. Which from his point of view is a feature, not a bug

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Actually I suspect that training and experience can make a big difference in most fields.
To whether that person is more likely than average to deliver truth?
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Old 16th July 2011, 06:02 AM   #103
wbeaty is offline wbeaty  United States
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Why would a colloquial word such as 'electricity' need to be defined in science, that's what I'm curious about?
It isn't. It's just wbeatty asserting that it is, as the same as 'electric charge'.
Don't be disengenuous. It's just wbeaty giving evidence for the scientific definition of the word "electricity." Did you miss it? Or are you just ignoring it, refusing to click on links, etc.? Evidence in the form of CRC handbook, the NIST website, and don't forget all textbooks which state that an electric current is a "flow of electricity."

Have you ever heard of electricity flowing? Isn't that what an "electric current" is? If so, then you've been using the original scientific definition, where "electricity" means "charge," and a flow of electricity is measured in amperes.

If a book says that, in AC systems the electricity moves rapidly back and forth, then that book is using the centuries-old scientific definition of the word "electricity."

Really the word "electricity" first had a clear scientific meaning, and all the colloquial definitions were piled on more recently. I've seen the confusion this has caused. The real question is, why do we need so many different incorrect colloquial definitions for a simple physics term?

Want more? Here's JC Maxwell himself. In the following he's using the term "electricity" with the same scientific meaning described by the references I gave. He makes some very interesting points about energy, so I encourage everyone to take a look.
Part I, ELECTROSTATICS, Chapter I DESCRIPTION OF PHENOMENA
Conductors and Insulators

"35] While admitting electricity, as we have now done, to the rank of a physical quantity, we must not too hastily assume that it is, or is not, a substance, or that it is, or is not, a form of energy, or that it belongs to any known category of physical quantities. All that we have hitherto proved is that it cannot be created or annihilated, so that if the total quantity of electricity within a closed surface is increased or diminished, the increase or diminution must have passed in or out through the closed surface."

<snip>

"There is, however, another reason which warrants us in asserting that electricity, as a physical quantity synonymous with the total electrification of a body, is not, like heat, a form of energy. An electrified system has a certain amount of energy, and this energy can be calculated by multiplying the quantity of electricity in each of its parts by another physical quantity, called the Potential of that part, and taking half the sum of the products. The quantities 'Electricity' and 'Potential', when multiplied together, product the quantity 'Energy.' It is impossible, therefore, that electricity and energy should be quantities of the same category, for electricity is only one of the factors of energy, the other factor being 'Potential.' "
See what happened there? Maxwell showed that electricity is not a form of energy.

He's just saying that coulombs are not joules, and since the word "Electricity" means electric charge, that's why Electricity is not a form of energy. Anyone who disagrees can go argue with the NIST standards committee. See if you can convince them that electricity is actually the motion of electrons, or that the quantities of Electricity should measured in Amperes. And when you get done convincing them, go and convince the physics community that JC Maxwell dishonestly tried to confuse everybody through his habitual incorrect use of the word "electricity."


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Originally Posted by DF96 View Post
Note that 'electricity' is not a term which physicists use very much, we prefer to talk about charge or current or electrons etc.
Very true. But it's a simple fallacy if you reason that, because you personally don't ever use it, or because the physics community tends not to use it too much, somehow this proves that "Electricity" has no physics definition. One look at various physicists writings, or one look at the CRC handbook, shows your error.

If the scientific community didn't use it at all, that would be different. But we still do say this: Faraday's Law is when we pass a quantity of electricity through an electrolysis cell, and it releases a quantity of gas, or deposits a quantity of electroplated metal. Each electron and proton carries a certain fixed quantity of electricity.

When getting into stupid arguments about terminology, usually you go to the dictionary for the real story. Often that doesn't work for physics terms. To settle physics arguments we instead go to major physics references. Ever heard of the SI units in physics? That org has a website. What does that website say? "Quantity of electricity" is to be measured in coulombs. That's good enough for me, but with some people, if they don't already know, you can't tell 'em.

Essentials of the SI: Base & derived units (down in table 3)
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Old 16th July 2011, 06:14 AM   #104
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Originally Posted by wbeaty View Post
Really the word "electricity" first had a clear scientific meaning, and all the colloquial definitions were piled on more recently. I've seen the confusion this has caused. The real question is, why do we need so many different incorrect colloquial definitions for a simple physics term?
But are the 'colloquial definitions' really definitions in the sense in which you use the word 'definition' ?

My second question is related to this. When I last used a dictionary, I found words which were polysemous. It would appear from what you're saying that beyond the first given meaning of the word, the subsequent meanings I find in a dictionary would have to be 'incorrect' (because in general, they're different). Am I reading you correctly?
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Old 16th July 2011, 06:27 AM   #105
wbeaty is offline wbeaty  United States
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Originally Posted by DF96 View Post
Any comments on the discussion about writing textbooks? Should an elementary book strictly avoid any 'untrue' statements, or is this impossible?
I think the solution is pretty simple. Go and find out if a statement in the books is causing student misconceptions. Or, record the known student misconceptions, then go back and see if the textbooks are the cause.

For example, most early chem textbooks teach us that atoms are like little solar systems. This is wrong. Years later we learn that atoms aren't like little solar systems after all. No big deal. The "solar system model" doesn't cause enormous learning barriers. It wasn't wrong, it was "wrong." It was a "lie to children," see Lie-to-children - Wikipedia, the free encyclopedia

On the other hand, many early science books clearly state that electricity is a form of energy, and then they also state that electricity flows around a circuit, passing through light bulbs etc. They say that it's made of electrons, and the electrons move at the speed of light. All this is wrong. But does it create misconceptions? OH yeah. In questioning science museum visitors, in observing students, and while tracking misconceptions in pop literature, I found that the wrong explanation has totally destroyed most people's ability to understand how electricity works. It's energy... yet it passes through a light bulb without any of it being consumed? And at the same time the light bulb turns electrical energy into heat and light? Okaaaaayyy.

And then people back carefully away from Electricity. They know it's totally dangerously insane. It might have a knife hidden behind its back! Better run away screaming.

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Originally Posted by DF96 View Post
My own view is that accuracy is important, but clarity may require some compromise. It helps, of course, if the writer is aware of when he is compromising so he needs to have a level of knowledge which exceeds the level of the book he is writing. Poor books can be written by people who don't realise when they are offering simplification or approximation, but people who are too advanced (or think they are) can also write bad books.
Another method is to make a large collection of typical student misconceptions. Then be incredibly careful while writing textbooks. (If people accuse you of pedantry, it's a good idea to ignore them.) After all, if you're not careful enough, your book could be the single original source of all those widespread student misconceptions which the education researchers are constantly complaining about.

Try this one:
AAAS - Project 2061 - Why some schools may not want to go by the book
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Old 16th July 2011, 06:51 AM   #106
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Originally Posted by abraxalito View Post
But are the 'colloquial definitions' really definitions in the sense in which you use the word 'definition' ?
They're found in dictionaries, encyclopedias, textbooks. Is that what you mean? The textbooks might not define terms, but instead just contain examples of a common usage. Sometimes one reference will stick to a single definition. But get a stack of books and you'll find that there is no single clear definition upon which experts agree. (Well, maybe the SI standards committee trumps everybody else.)

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Originally Posted by abraxalito View Post
My second question is related to this. When I last used a dictionary, I found words which were polysemous. It would appear from what you're saying that beyond the first given meaning of the word, the subsequent meanings I find in a dictionary would have to be 'incorrect' (because in general, they're different). Am I reading you correctly?
Maybe not. Example, "Crane" is defined as a migratory wetlands bird which eats frogs and small fish, and also is defined as a tall metal gas-powered machine for lifting heavy objects. The second definition isn't wrong.

But if this was a typical K-12 textbook electricity chapter, we'd define "crane" as a man-made migratory metal gasoline-powered shorebird hundreds of feet tall which lifts heavy objects and subsists on a diet of frogs and small fish. Textbooks would show an artist's conception.

That's what happens when we define electricity as "electric charge," then we change our minds and define it as energy, then we change our minds and define it as the flowing motion of charge. Then we say it's an entire class of phenomena. Then we say that it's the transfer of energy, as in "watts of electricity." And don't forget "volts of electricity." Then we publish textbooks which contain all these usages (maybe in a single book!) Then we go out and teach kids all about "Electricity." If they grow up to be physicists and engineers, they escape the problem by abandoning all hope of any visual/intuitive understanding, and instead just learn the equations.

I built a device to help educators cut through the morass. It makes electric current visible:
VISIBLE ELECTRIC CURRENT
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Old 16th July 2011, 07:16 AM   #107
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Originally Posted by wbeaty View Post
They're found in dictionaries, encyclopedias, textbooks. Is that what you mean? The textbooks might not define terms, but instead just contain examples of a common usage. Sometimes one reference will stick to a single definition. But get a stack of books and you'll find that there is no single clear definition upon which experts agree. (Well, maybe the SI standards committee trumps everybody else.)
Right, and if the textbooks in (say) physics can't agree what hope have dictionaries and encyclopedias of agreeing when it comes to words in everyday parlance? That was where I was leading - they do not fit your word 'definition' because they're imprecise. Whereas a definition of 'electricity is electric charge' is fairly well pinned down and so, to me, this does count as a definition. But colloquial words, er by definition don't have precise definitions because they're so context dependent.


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Maybe not. Example, "Crane" is defined as a migratory wetlands bird which eats frogs and small fish, and also is defined as a tall metal gas-powered machine for lifting heavy objects. The second definition isn't wrong.
Right, so different meanings are not necessarily 'wrong' then. So I'm led to enquire - what leads you to say that the more recent colloquial meanings for the word 'electricity' are 'incorrect'?

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That's what happens when we define electricity as "electric charge," then we change our minds and define it as energy, then we change our minds and define it as the flowing motion of charge.
But we don't need to 'change our minds' as you're suggesting. We merely need to recognise that context is important in determining a word's meaning. If I'm at a wildlife park then the word 'crane' suggests something quite different from if I'm wearing a hard hat at a building site. I did not have to 'change my mind' to encompass both meanings.
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Last edited by abraxalito; 16th July 2011 at 07:25 AM. Reason: misattribution
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Old 16th July 2011, 01:31 PM   #108
DF96 is offline DF96  England
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The fact that charge is not gained or lost is perfectly consistent with charge being a form of energy.
wbeatty, quoting DF96 (with modifications).

That is a true statement, although you misunderstood why I said it. I said it because you appeared to say that electricity (by which you mean electric charge) is conserved, therefore it can't be a form of energy. The statement "conserved implies 'not energy'" is a false statement. As you now know, I was not asserting that charge=energy but conserved=could be energy.

You quote Maxwell trying to understand/teach something about this strange new stuff called electricity. The context shows that he is clearly talking about what we now call electric charge. He is showing that electric charge is not energy. He calls it electricity because it is a good name to use. He is not defining electricity, but seeking to explain it. As I said, physics is about understanding not definitions. Your confusion arises because you persist in sticking to your assertion that 'electricity' means 'electric charge' and only 'electric charge'. When I am sent an electricity bill should I query it and complain that the electricity company hasn't given me any electricity at all, but removes via one wire all the electricity it gives me via the other wire? Do you complain to your electricity company? You should if you wish to be consistent.

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If they grow up to be physicists and engineers, they escape the problem by abandoning all hope of any visual/intuitive understanding, and instead just learn the equations.
I don't think I have met any professional physicists or engineers who have trouble understanding electricity. Hobbyists, yes. First-year students, yes. Maybe your experience is different. I have met physicists who appear to have abandoned intuitive understanding and just do calculations, but this was in fields like quantum gravity where intuition can easily lead people astray. These people stuck out precisely because this way of doing things is unusual in physics.

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On the other hand, many early science books clearly state that electricity is a form of energy, and then they also state that electricity flows around a circuit, passing through light bulbs etc. They say that it's made of electrons, and the electrons move at the speed of light.
The only false statement here is that electrons move at the speed of light. I am quite happy with saying that electricity is a form of energy because by doing that I am not defining a word but identifying a group of related phenomena. I don't put emphasis on "is". I am starting from what is familiar (most people have heard of electricity - its what they run their TV on), which is usually a good teaching technique. I might then go on to talk about the quantity of electricity, and introduce the idea of electric charge. To simply say that electricity is electric charge is unhelpful, as you have just swapped one familiar term for another unfamiliar one without explaining either. If it would make you happy it ought to be possible to teach about electricity without ever using the word, except in the final sentence of the book.
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Old 16th July 2011, 05:17 PM   #109
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Important issues because of the impact on young students (my eleven year old daughter).
My opinion is: instruction should lead to the desire and ability to learn more.

Of course I believe that consistency is important but as I see it, its not the main ingredient. Misinformation is wrong, but so is biasing a young mind to accept rigid definitions of the way we currently define our understanding. Ones visual/intuitive understanding often comes from having to reconcile the different information presented to us.

This latest discussion of the word electricity has at least forced me to re-think my understanding.
I have thought of electricity as related to static or dynamic charge but not in the sense of Coulomb's but rather many aspects, current, voltage, power etc. If it does indeed have an official definition of 1 coulomb I can accept that, but I would like to know what is the the officially defined word to be used in place of the colloquial “electricity”.

Just in trying to follow the arguments I'm getting more confused, if electricity is defined as 1 coulomb then it can be electrons flowing or static charge. Never considered Physics to be built from definitions but rather concepts and interactions.

Bottom line I would feel grateful for instructors to lead and write texts that open minds and encourage independent thinking even at the expense of inconsistencies, especially since we really don't know it all and inconsistencies are a part of it (if they can do this, I believe their “facts” and “definitions” will be more than adequate and not confusing unless meant to be).
I'm not smart enough to be a physicists but I have worked for and with many of them, and just love the way they can see the picture without definitions getting in their way.

Hope this helps
-Antonio
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Old 21st July 2011, 03:32 AM   #110
wbeaty is offline wbeaty  United States
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Originally Posted by abraxalito View Post
Right, and if the textbooks in (say) physics can't agree
Who says they don't agree? That's not my experience. Give evidence: which physics texts in particular are you talking about?

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Originally Posted by abraxalito View Post
what hope have dictionaries and encyclopedias of agreeing when it comes to words in everyday parlance? That was where I was leading - they do not fit your word 'definition' because they're imprecise.
Who say's they're imprecise? I've found the opposite to be true. Give evidence: name any of the common definitions, and show why they're imprecise.

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Originally Posted by abraxalito View Post
Whereas a definition of 'electricity is electric charge' is fairly well pinned down and so, to me, this does count as a definition. But colloquial words, er by definition don't have precise definitions because they're so context dependent.
No, that's silly. The colloquial definitions are very precise, but they contradict the accepted scientific definitions.

Here's an example of a colloquial definition:
Electricity is the flowing motion of charges within a conductor. The amount of electricity is measured in amperes
The above definition appears very widely, and is the version commonly adopted by K6 science texts. According to the above, 'electricity' isn't charge, instead it's the rate of charge flow or transfer.

Here's another:
Electricity is a form of energy. It's produced by batteries and generators, and sold by electric utility companies. It's usually measured in KWH
The above definition appears widely too. According to this one 'electricity' isn't charge, nor is it charge-flow; instead electricity is electromagnetic energy. It contradicts the original scientific definition.


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Right, so different meanings are not necessarily 'wrong' then. So I'm led to enquire - what leads you to say that the more recent colloquial meanings for the word 'electricity' are 'incorrect'?
Because they're narrow and precise, and they contradict the scientific definition.

If someone tries to redefine the word "black" to mean white, or redefine the word "circle" to mean square, that's called "being wrong."
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