SY,
Correct me if I'm wrong I remember someone saying they would like to throw all books with "sun & planet" system atoms in the bin! Who was that?
So what's the chance of a few pictures and info of "electron flow" and explanation...unlearning the wrong. 🙂
I bet many folks would find it interesting..if put in easy terms.
Regards
M. Gregg
Correct me if I'm wrong I remember someone saying they would like to throw all books with "sun & planet" system atoms in the bin! Who was that?
So what's the chance of a few pictures and info of "electron flow" and explanation...unlearning the wrong. 🙂
I bet many folks would find it interesting..if put in easy terms.
Regards
M. Gregg
Dave, it's turtles all the way down.
MG, sun and planet have to do with how atoms and molecules are put together. It's irrelevant to electron flow- or any other sort of charge flow. Rather than rehash some excellent textbooks which already exist, I'd refer you to one of my favorites: Shive and Weber, "Similarities in Physics."
MG, sun and planet have to do with how atoms and molecules are put together. It's irrelevant to electron flow- or any other sort of charge flow. Rather than rehash some excellent textbooks which already exist, I'd refer you to one of my favorites: Shive and Weber, "Similarities in Physics."
No, sun and planet is thoroughly wrong and can't really be fixed. The core electrons and the nucleus can be thought of as pretty much a featureless sphere. Conduction electrons act more like a diffuse gas and can't really be associated with individual atoms. Concepts like delocalization, exclusion, exchange, and indistinguishability are really quite simple, but totally counterintuitive. There's no analogy to them in quotidian life.
Yep.
Well, actually it was obviously my fault for not being clear enough. Some history:
There's an entire sub-field of physics education which deals with the major learning barriers caused by student misconceptions. I think the field first appeared in the late 1970s when "Naive Conceptions" suddenly took off as a hot physics-edu subject (mostly in TPT and Science Teacher magazines, and see http://physics.indiana.edu/~hake/AronsAdvMeth-8.pdf .) I watched as it quickly grew to include all misconceptions, not just the pre-classroom ones. Misconception- fighting curriculum programs appeared (even in electricity, for example Steinberg/Wainwright's famous supercapacitor-based C.A.S.T.L.E. project. http://www.pasco.com/featured-products/castle/ , AAPT The Physics Teacher: Using Models to Teach Electricity Cookies Required )
I became directly involved myself when working on designs for the Electricity exhibit at Museum of Science around 1987. To develop materials, I referred to the pros: to the major K6-grade science texts for the "right way" to explain electricity. Big mistake. I discovered they were completely full of egregious physics errors. Not the quibbles, but complete distortions of simple physics. (see Index to the Web site of The Textbook League for examples in all topics.) I realized that many of those physics errors were still in my own head. After all, I'd been through the K6 grades myself, and the modern K6 books weren't much changed over 20yrs. As a kid I'd been a straight-A teachers'-pet science fanatic, so I concluded that if my concepts of electricity were damaged by screwy textbooks, then probably everyone else had a similar problem. And ...this strongly suggests that a portion of students' physics misconceptions aren't Naive Concepts, and aren't picked up accidentally.
Instead they're intentionally taught by K6 science textbooks.
Therefore I decided to add misconception-fighting techniques to our Electricity exhibit devices. What misconceptions? There were very few refs back then (though the ref at the end of this was an excellent start.) I started collecting "Electricity Misconceptions" from K6 textbooks, from visitors using our exhibit prototypes, from museum design staff, from research papers, pop books/magazines/texts, and especially from my own head. The unedited version is WHY HARD: Why Electricity is Impossible to Understand
I crafted a set of new electricity explanations for Museum of Science. Rather than following any existing K12 texts, instead I took undergrad physics and engineering textbooks and translated their math models into verbal explanations aimed at the US 6th grade level. I designed an LED chaselight device to "make electricity visible" in actual working circuitry. Both are now in the exhibits and text at MOS Boston. But also the material sat for years in my filing cabinet. Not having any classroom experience, I couldn't very well write a teaching manual!
Internet appears. I discover PHYS-L and TAP-L, the physics teaching forums. I start bringing up the EM misconception issues and distilling my museum exhibit notes into simple essays, and over years I heavily discuss these on the two forums. Those essays aren't my eccentric personal take on EM teaching ...they are my eccentric personal take on EM teaching as vetted by physicists at the university level. (Well, the actual process was piecewise and unofficial; far from actual "peer review." Many PHYS-L people read my papers and sent public and private comments, but the vast majority probably did not.)
My online essay collection has been in heavy use by science teachers for almost two decades now. I receive lots of email questions/commentary and am constantly making revisions to the writing (sample at Electricity Questions Answered [The Science Hobbyist]) The actual mistakes were cleaned out by PHYS-L in the early 1990s. Unclear parts are vastly reduced, but there's still far to go before I'd want to get them published.
Over the years I see three kinds of responses: physicists and physics educators love my material. It's right out of their textbooks ...but all verbal, no equations. They can use it for public lectures and grade school demos. Engineers and techs usually say "it's OK, but what's the big deal? Not useful, except perhaps for teaching newbies." (Well yes, that was the whole point.) A third and relatively tiny group absolutely loathes the essays, sending me long messages full of, at best, streams of logical fallacies, and at worst, huge volumes of ad hominem. They almost never point out one single error.
When someone say's my material contains any mistake, I take it very seriously. Even if it's not an outright error, it might be an unclear misleading section which needs rewrite. So, which of my articles has the problem (I need the url.) Which paragraph? Copy/paste the offending sentences if you can.
When I say it ...in one of my articles? Or you mean here on this forum?
Instead I try to make clear that, if "electric current" is a flow of electricity, then electricity cannot be a form of energy, since it flows through the flashlight bulb and it all returns to the battery without any of it being converted into heat. If electricity was a form of energy, then the flow into one resistor terminal would have to be larger than the flow coming back out. Part of it would exit as watts of heating, part would return to the battery.
Conclusion: either we must declare that Electric Current is not a flow of Electricity, or we must declare that Electricity is not a form of energy. How to decide between these two? Go to the top physics references. They say that "electricity" has pos or neg polarity, flows as electric current, and is measured in coulombs.
So any book which says "Electricity is a form of energy" is misleading its audience. The authors are confused about the difference between watts versus amperes. (This is like being confused about the difference between water in a river, versus hydro energy extracted by dams.)
ref:
McDermott, L.C. & van Zee, E.H. (1984). Identifying and addressing student difficulties with electric circuits. Proceedings of the International Workshop: Aspects of Understanding Electricity, Pdagogische Hochschule Ludwigsburg, W. Germany, pp. 39-4
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For understanding current flow through resistors, wires, and capacitors, fluid concepts are surprisingly accurate. There is no good Machian analogy to how semiconductor junctions work, unfortunately. There's nothing else to do than to start thinking about band theory, and that involves some basic quantum mechanics, I'm afraid.
This brings us back to how do you teach a subject and remove barriers.
The nonsense example-
There is a simple way its like this "imagine"....
A magnet spinning around another magnet (this can be your atom)
The speed centrifugal force can offset the magnetic attraction so the spinning one stays in orbit. The outer magnets are all the same polarity.
How much push do you need to overcome the magnetic attraction of the spinning magnet to the one in the centre. This is voltage or pressure applied. When the pull is over come this is conduction. If each of our imaginary atoms were in line each magnet would be pushed to the next because the polarity of all spinning magnets are the same.
The higher the magnetic attraction to the center the more push or voltage you need to push the spinning magnet to the next "atom"
This is resistance.
Everything will conduct with sufficient push " voltage applied". Even the air " lightning.
A circuit is like marbles in a circle of pipe with no gaps. if you move one they all move at the same time. At no time is there no marble under your finger. This is Kirchhoff’s law what goes in comes out.
Very simple and basic.
Just for fun.
M. Gregg
NO! NO! Please excuse the shouting, but this is the very point we have been arguing. We do not have to declare that electricity is any one thing - that is your fundamental mistake. Electric charge is one thing. Electric current is one thing. Electrical energy is one type of energy. We do science and engineering using those concepts. Please stop using electricity as a precise 'scientific' term. You are creating confusion.wbeatty said:
and completely wrong! It would take too long to explain all the misconceptions in this model. I will pick just one: resistance does not arise from the energy needed to push an electron to the next atom (as you get all that energy back at the next atom), but from the energy needed to overcome random scattering. Resistance is a bit like friction.M Gregg said:
I agree,
Remember this is a way of creating an idea, Its not going to be electrically correct. It is a way of breaking the ice so that you can then modify the idea. The nonsense example!
Regards
M. Gregg
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I am confused (I get easily confused!). In order to get the correct idea across, you deliberately give some completely wrong and misleading ideas so that you can then correct them? Simplified ideas, yes. Completely wrong ideas, no.M Gregg said:
This is a concept,
EG describe the colour yellow to someone blind from birth. You can only say it's like this its like that. You will never achieve this!
If you can start the ability to visualize you can then expand the idea.
The lesson is to visualize an electrical idea. Then modify it.
This is linked to learning styles.
When you start a course you need the entry behavior to get on it.
Some people can read a book and understand, some need ideas and pictures. Some need both. Some need to be told the same things in different ways. The important thing is that in the end they can visualize and understand the information.
Just for interest,
You have just proved the model. You have visualized the model and found fault. Some people cannot do this because they cannot visualize information.
Regards
M. Gregg
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I'm not certain I did visualise it. I just thought that magnetism is a poor model for electrostatic forces, and conservative forces are a bad model for dissipative forces.
Part of the art of choosing models is to pick appropriate models, even if you can't/don't tell your pupils why they are appropriate. This reduces the amount of stuff they have to unlearn later.
I don't accept the 'learning styles' concept. Learning styles must fit the subject, not the pupil. You learn mathematics by sitting down with a pencil and paper. You learn football by running around a field. Swapping over 'learning styles' would be unproductive, yet this is what some teachers seem to believe.
Part of the art of choosing models is to pick appropriate models, even if you can't/don't tell your pupils why they are appropriate. This reduces the amount of stuff they have to unlearn later.
I don't accept the 'learning styles' concept. Learning styles must fit the subject, not the pupil. You learn mathematics by sitting down with a pencil and paper. You learn football by running around a field. Swapping over 'learning styles' would be unproductive, yet this is what some teachers seem to believe.
Just for interest.
You say people learn Maths with paper and pen, I can't remember now if it was in China or Japan. Students do Maths with an abacus. They can add / subtract etc faster than a person with a calculator. When they do this after mastering the abacus they do it with out one. You can see them moving imaginary beads with their fingers and visualize the abacus. They are just as fast.
Regards
M. Gregg
You say people learn Maths with paper and pen, I can't remember now if it was in China or Japan. Students do Maths with an abacus. They can add / subtract etc faster than a person with a calculator. When they do this after mastering the abacus they do it with out one. You can see them moving imaginary beads with their fingers and visualize the abacus. They are just as fast.
Regards
M. Gregg
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Have you had the chance to discuss the airfoil issue with a real engineer? And, you need to fix your airfoil lift errors, as a rotating cylinder creates lift in an airstream, yet you've stated the the trailing edge needs to point down..
I KNEW IT!!!! Eureka!
Cheers, John
Different methods for performing arithmetic are equivalent if they give the same answers. This is not really a learning style issue, as in either case something concrete stands for a number : either symbols on paper, or positions of beads.
The 'learning style' people want us to believe that you can learn arithmetic by running around, or learn football by reading the rules. OK, maybe I am exaggerating a little but the main point is that the style should suit the topic rather than the pupil. A bright pupil can use any learning method, as appropriate. A weaker pupil may be restricted in styles, so some topics may be beyond him.
The 'learning style' people want us to believe that you can learn arithmetic by running around, or learn football by reading the rules. OK, maybe I am exaggerating a little but the main point is that the style should suit the topic rather than the pupil. A bright pupil can use any learning method, as appropriate. A weaker pupil may be restricted in styles, so some topics may be beyond him.
My best high school math teacher always said "Math is not a spectator sport, you have to work through it yourself or you will never learn it." This meant of course everyone in class got their turn to solve problems at the board.
🙂
No standardized tests for me when I was in school, ie pick the one that looks the rightest
it was all fill in the blank and show your work as you are graded on it, or use your own paper for the test.😛
I wonder why kids can't figure change in their heads working a cash register any more.
...🙄
🙂No standardized tests for me when I was in school, ie pick the one that looks the rightest
it was all fill in the blank and show your work as you are graded on it, or use your own paper for the test.😛I wonder why kids can't figure change in their heads working a cash register any more.
...🙄
Just for interest,
In the model the word resistor was not used.
If we measure the resistance of a piece of plastic we will get a resistance value in Megohms. If we apply a voltage across it (and keep increasing the value) at what point does it flash over. Why does it flash over?
At what point does electron scatter come in?
Regards
M. Gregg
In the model the word resistor was not used.
If we measure the resistance of a piece of plastic we will get a resistance value in Megohms. If we apply a voltage across it (and keep increasing the value) at what point does it flash over. Why does it flash over?
At what point does electron scatter come in?
Regards
M. Gregg
The resistance of most plastics will be FAR higher than megohms (there are a few exceptions, but their conduction mechanisms are quite exotic). Dielectric breakdown has nothing to do with electron scatter in a resistance sense.
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