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.
Actually I suspect that training and experience can make a big difference in most fields.
🙂
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 😀
To whether that person is more likely than average to deliver truth?
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.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.' "
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."
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)
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?
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.
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
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.)
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
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.
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'?
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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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.
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.
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.
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
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
Who says they don't agree? That's not my experience. Give evidence: which physics texts in particular are you talking about?
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.
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.
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."
I'm not "suggesting." Instead I'm giving a capsule history of the changes to the word "electricity" over time. We as a culture changed our minds, but did it silently without discussion. I'm describing what actually happened in the real world.
Originally the meaning of "electricity" was a bit fuzzy in the 1600s. Then it grew to have a fairly precise scientific definition: it meant much the same as "charge" means today. In other words, quantity of electricity was quantity of vitreous or resinous electricity, later renamed "positive" and "negative." A metal sphere can be charged with a quantity of electricity, and if electricity is moving then you have electric current.
But then with the rise of the electric utility companies, "electricity" was redefined to mean the same as electromagnetic energy. (This of course directly contradicts the definition of electricity=charge.) But this is a big problem, since the charges move fairly slowly during electric currents, yet the energy moves at almost the speed of light. Both can't be the electricity. It would be like defining air molecules as a kind of sound wave, or like saying that sound waves were made of nitrogen molecules flying through space at 720MPH.
Still later the grade-school textbooks started defining 'electricity' not as charge or energy, but as the motion of charges; as electric current. So now the quantity of electricity is measured in coulombs per second or amperes, not in coulombs or in KWH. But electric current is not energy, nor is it charge, so this third definition contradicts both of the earlier ones. Analogy: we say that nitrogen is made out of sound waves, and that sound and wind are the same thing.
CHILDREN are expected to do this? You're joking. In the K6 classroom, children are expected to know that the word "electricity" has several different precise definitions? And that the several definitions contradict each other? And then they somehow have to know which of the contradictory definitions are being used in any sentence?
No.
Instead kids come to think that just one single "electricity" exists ...but obviously this electricity is impossible to understand. It's impossible to understand because "electricity" passes through a light bulb filament and none of it is used up, but at the same time "electricity" is consumed by the bulb and converted into light/heat output. How can it be consumed, yet also every bit must flow out of the second wire and returns to the battery? And, while "water" is a clear and sensible concept which is measured in gallons, "electricity" is measured in coulombs, amperes, and KWH, all at the same time. (No, actually it's not. Three entirely separate concepts have been mixed together. The contradictions turn the entire topic into tangled garbage.)
As I said before: textbooks mix several narrow distinct definitions together, then present them to children. They do the equivalent of teaching kids that "cranes" are birds made of steel; birds which are simultaneously five feet and 50ft tall; birds which are powered by eating frogs and also by burning gasoline.
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I think you seriously misunderstand our natural language abilities - with children being extremely mentally flexible
the problem becomes trying to pin down semantics, meaning for "linear", "logical reasoning" that we pretend can lead to "self discovery" of scientific principles if somehow we were only able to teach the basics "Right" in the 1st place
human learning, discovery is not in the main linear, logical - that is a structure/"story line" imposed after the fact
the problem becomes trying to pin down semantics, meaning for "linear", "logical reasoning" that we pretend can lead to "self discovery" of scientific principles if somehow we were only able to teach the basics "Right" in the 1st place
human learning, discovery is not in the main linear, logical - that is a structure/"story line" imposed after the fact
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Oddly enough , you did. Here's what you said :
But get a stack of books and you'll find that there is no single clear definition upon which experts agree.
But if you read what I wrote then you'd discover I wasn't talking about definitions, rather words in everyday use. I'll leave you to uncover the relevant context.
Once again, I was not speaking about colloquial definitions. I explained that 'colloquial definition' was pretty much an impossibility.
I'm done here as this is a long way from being generative dialogue. Oh and you will benefit from revisiting (if you visited it the first time) the rules on apostrophes page I linked to because you're still not getting it 😀
Student misconceptions in physics are fairly well understood, no big mysteries. Kids find some topics easy to learn, while others are difficult or even impossible. Electrical physics is one of the most difficult ones. It's my own conclusion that the problem of student electricity misconceptions is mostly caused by mistakes in textbooks, actual widespread mistakes, not slight semantic quibbles. Many students end up like me: they go in to physics or electrical engineering, give up on visualizing the details inside circuits, and instead just use math models. That does an end-run around the misconception problem, but it keeps us from understanding electricity in the way that we can understand, say, machines. (Yes, hydraulic analogy helps greatly, but hydraulic analogy doesn't appear in textbooks aimed at the earlier grades. Usually only the techs and engineers ever get to hear about it.)
A great book on student electricity misconceptions is:
ASPECTS OF UNDERSTANDING ELECTRICITY: PROCEEDINGS OF AN INTERNATIONAL WORKSHOP, R. Duit, W. Jung, C. von Roneck (Eds),
Verlag Schmidt & Klaunig, 1985 (QC530.A78 1985)
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That's what I'm hoping to accomplish with my online collection of simple descriptions on how electricity works.
That's the topic of this thread, right? I publish online curriculum material for science teachers and students. Mine is unusual in that I remove contradictory uses of words, and I subtly attempt to cure some of the common misconceptions which are known to act as learning barriers.
If you haven't encountered them, then we're not on the same page here. Go try this one:
Watts, Ohms, Amps, Volts
Electrical curriculum: watts, ohms, volts, and amps
Also:
Answers to Electricity Questions (FAQ)
SCIENCE HOBBYIST: Electricity F.A.Q.
The whole collection is here:
Articles on "Electricity" . . . . WJ Beaty
You have not been successful; simplicity is where you falter. The more you strain at the gnats, the less people care to listen. You can be correct all day long, but I for one am satisfied with my usage of the word 'electricity'. Your quoting of physics books won't change that, and I have one on my bookshelf that I open from time to time. It is my job to communicate power system recommendations to laymen in my reports every day. If I communicated with your pedantry, I would be out a job. Whether I write "electricity flows" or "current flows" is irrelevant to the customer who just wants an answer they can comprehend.
No, most misconceptions are caused either by lack of ability or poor teaching. A problem in the UK is that far too many schools have no physicist on the staff, so physics has to be taught by someone from a different discipline. A different problem happens in university engineering departments: too little physics is taught, often not by physicists, and approximations and simplified models are taught as absolute truth (explicitly or implicitly).wbeatty said:
I had two physics teachers in secondary school. One aimed at understanding. The other was a pedant, and aimed at definitions. Unfortunately the second one also taught organic chemistry by what I call the 'recipe method' - no understanding, just learn that 'this+this=that'. As a result I never got to understand organic chemistry, but was fine with physical and inorganic as the teacher for that was a real chemist.
How did I know the teacher was a pedant? Here is a conversation I heard on a number of occasions:
Pupil "Please, sir, can I borrow your biro?"
Teacher "I'm sorry, I don't have a Biro. I am happy to lend you my ball-point pen (which was made by Bic)."
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From a layman's point of view, it would seem that the massflow concept is correct. That said...
Consider a real airplane wing with trailing edge flaps. There are times when the trailing flap is positioned such that the massflow coming off the trailing edge is parallel to the ground and the direction of flight. So no net massflow down yet the plane does not flip as a result of zero lift. Does a plane immediately lose all lift if the main flaps are horizontal to fligh direction? Does this mean that if I design an airfoil twice as long by extending the trailing edge very thin, that this airfoil will have no lift whatsoever?
The net massflow argument (or any argument for that matter) must be capable of explaining all actions which were defined and modelled based on previous understandings. If one instance counter to the argument fails, the argument must be discarded.
Cheers, John
Ugh, DF96, you brought up my particular sore point. That's the way organic chemistry was traditionally taught, memorize reactions and the names associated with them. As an experiment, my undergrad institution decided to teach the course by considering structure/reactivity and mechanisms. For me, this was wonderful- for the majority of students (who were pre-med), not so much. They just wanted lists to memorize; I could sympathize, since their entrance and qualification exams would ask questions like, "Give an example of a Mannich reaction." It did them no good to be able to recognize that the nonbonding electron pair of an amine will be nucleophilic, that the carbon of a protonated aldehyde will be electrophilic, and the reaction pathway will lead to an addition followed by a dehydration. No, their exams wanted "an example of a Mannich reaction," so it was important for them to know the name and know that "formaldehyde plus primary amine gives Schiff base."
The experiment was dropped after a year because of the complaints. I was fortunate to be taking organic during that one magic year, and it allowed me to test out of two of the graduate chemistry courses I would have otherwise had to suffer through.
The experiment was dropped after a year because of the complaints. I was fortunate to be taking organic during that one magic year, and it allowed me to test out of two of the graduate chemistry courses I would have otherwise had to suffer through.
I enjoyed chemistry so much at school (apart from organic) that I considered studying it at university instead of physics. I was fascinated by the idea that given an atomic number I could make a stab at guessing electron arrangements, then from that predict likely elemental properties. This seemed like real science! I am concerned to hear that my experience of organic may be typical - I just assumed I had a bad teacher.
The 'physics' taught to some EEs is not much better than organic chemistry recipes. "This is what it is called; this is the formula; now go and plug some numbers in".
The 'physics' taught to some EEs is not much better than organic chemistry recipes. "This is what it is called; this is the formula; now go and plug some numbers in".
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