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Topic: Flow of electricity - Simple Circuits (Read 12301 times) previous topic - next topic

polymorph

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But one can have a charge without flow, as in static electricity, so that doesn't answer the question of what is the direction of current flow and what is actually flowing in a DC circuit wired to a voltage source.


I don't get your point. One can have water without it flowing.

What is actually flowing in a DC circuit depends. Through a wire, electrons. Through a battery (parts of it), the majority charge carriers are positively charged ions. Negatively charged electrons are pulled to the more positively charged parts of the circuit (battery, generator, etc) and if positively charged ions are flowing, they move towards the more negatively charged parts.

Holes are just fictions, models created to aid in approximating semiconductor behavior. Within those limitations, you treat a hole as if it were a positively charged particle.

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So do you agree that holes are not real, but rather just a means to explain how solid-state material supports current flow?


I've never said any different. It isn't a means to explain how solid state material supports current flow, after all, copper is a solid. It is a means to more easily model semiconductor action. So we say that electrons obliterate holes, we act as if holes were virtual positively charged particles, sort of anti-electrons. But it is just a model.

Heck , the so-called free electrons are not really free. N-type is not really negatively charged, those are not really excess electrons.

It is all an aid in understanding. Approximations. Like having an approximation of a diode being just a one-way valve, or the approximation that a diode drops 0.7V.

I don't know of any credible physicists or EEs who claim that holes are real, or who claim that "conventional current" is really holes flowing. I've known a few ignorant instructors who've said some stupid things. Heck, you should see my review of Sams "CET Study Guide 4th Edition", that's my review at the top:

http://www.amazon.com/CET-Study-Guide-Joseph-Risse/product-reviews/0070529337/ref=dp_top_cm_cr_acr_txt?ie=UTF8&showViewpoints=1

Or my review of "RESIDENTIAL CONSTRUCTION ACADEMY: ELECTRICAL PRINCIPLES", a popular textbook on electricity for electricians. The author has written -loads- of highly regarded texbooks, yet everyone I've been able to see a preview of has the same horrible, basic mistakes.

http://www.amazon.com/RESIDENTIAL-CONSTRUCTION-ACADEMY-ELECTRICAL-PRINCIPLES/product-reviews/B00B7BCA5O/ref=dp_top_cm_cr_acr_txt?showViewpoints=1

So there is a lot of bad information out there. And at least a few ignorant but well-placed people writing books.
Steve Greenfield AE7HD
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polymorph

That dufus who wrote "Residential Construction Academy: Electrical Principles" released a new edition. A quick scan of the pages available on Amazon turns up a few gems including his assertion of conventional current as a "theory" and that we've "established almost to a certainty" that electron flow is correct. Derp.

So I see where people could get confused about this.

The same guy asserts that the effects of electricity in a wire travel faster than the speed of light. Another derp.

Steve Greenfield AE7HD
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retrolefty

#32
Feb 07, 2014, 12:26 am Last Edit: Feb 07, 2014, 12:28 am by retrolefty Reason: 1

That dufus who wrote "Residential Construction Academy: Electrical Principles" released a new edition. A quick scan of the pages available on Amazon turns up a few gems including his assertion of conventional current as a "theory" and that we've "established almost to a certainty" that electron flow is correct. Derp.

Well in this case I agree with the derp, 'conventional current flow' is a myth and unsubstantiated no matter how it is spun. Current does flow and electrons are the flowing carriers.

So I see where people could get confused about this.

I agree, it's a topic that has confused people learning electronics for generations and I suspect will never go away.


The same guy asserts that the effects of electricity in a wire travel faster than the speed of light. Another derp.

In this case the derp is wrong, Einstein stated such.


I have found this discussion enjoyable and hope people can see that topics like this can be discussed without flaming and personal insults, but rather that there is room for technical disagreement while still respecting peoples opinions. It's not so important about being right or wrong, but rather that one can participate with mutual respect.

Lefty

polymorph

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That dufus who wrote "Residential Construction Academy: Electrical Principles" released a new edition. A quick scan of the pages available on Amazon turns up a few gems including his assertion of conventional current as a "theory" and that we've "established almost to a certainty" that electron flow is correct. Derp.


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Well in this case I agree with the derp, 'conventional current flow' is a myth and unsubstantiated no matter how it is spun. Current does flow and electrons are the flowing carriers.


My point was that he presents conventional current as if it were still considered correct by some and that there is still some doubt about electron current flow. Conventional current is not a theory, in the scientific use of the word.
Steve Greenfield AE7HD
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polymorph

When it comes to books aimed at beginners, books that have gone through multiple editions, I lose my patience with the amount of incorrect information.
Steve Greenfield AE7HD
Drawing Schematics: tinyurl.com/23mo9pf - tinyurl.com/o97ysyx - https://tinyurl.com/Technote8
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retrolefty

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My point was that he presents conventional current as if it were still considered correct by some and that there is still some doubt about electron current flow. Conventional current is not a theory, in the scientific use of the word.


Well my point is that 'conventional current flow direction' has no useful place in the teaching of electronics, it adds no value and only confuses. Just teach that current flows in DC circuits from negative to positive via electrons. I would just eliminate all reference to 'conventional current flow' and just explain that the arrows drawn on semiconductors symbols are backwards because the Physic and EE world would not live up to their original misunderstanding of what carries that current. Recall that electricity was being discovered and attempted to be explained before there was a complete understanding of atoms and their structure. They just guessed wrong about the direction of flow.





polymorph

This book, page 40 he discusses conventional current "theory" as if it were anything but a simplification, and aid in following what is happening in a circuit.

http://www.amazon.com/Residential-Construction-Academy-Electrical-Principles/dp/1111306478/ref=sr_1_9?s=books&ie=UTF8&qid=1391731676&sr=1-9

On page 41, he claims the "impulse of electricity can travel faster than light". For those following along, the speed of light is a limit on the speed of information, too. In this case, basically the electrons pushed into one end of a wire don't just go down the wire and out the other side, instead it is like turning on a pump - water pushed in one end results in water already in the pipe coming out the other end.

But the jostling of electrons cannot travel even as fast as light, because it is the result of physical objects, electrons, which cannot travel even at the speed of light, repelling other electrons.


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Well my point is that 'conventional current flow direction' has no useful place in the teaching of electronics, it adds no value and only confuses. Just teach that current flows in DC circuits from negative to positive via electrons. I would just eliminate all reference to 'conventional current flow' and just explain that the arrows drawn on semiconductors symbols are backwards because the Physic and EE world would not live up to their original misunderstanding of what carries that current. Recall that electricity was being discovered and attempted to be explained before there was a complete understanding of atoms and their structure. They just guessed wrong about the direction of flow.


I agree with you. Partly it has to do with instructors being more comfortable with conventional current flow. I'm part of a maker club here called OlyMEGA, and a lot of the 20 somethings don't even want to hear about "conventional" current flow. That makes me happy. I made myself look at circuits both ways back when teachers and books all stuck with "conventional" flow, with the exception of maybe a couple of mentions of electron flow near the front of the books.

But then, I have been cheering for the US to convert to the metric system since I found out about it.
Steve Greenfield AE7HD
Drawing Schematics: tinyurl.com/23mo9pf - tinyurl.com/o97ysyx - https://tinyurl.com/Technote8
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retrolefty

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I agree with you. Partly it has to do with instructors being more comfortable with conventional current flow.

Well some instructors maybe. As I said my Air Force electronics instructors were quite clear about it and told us to just ignore the EEs that tried to spin other explanations of current flow and it's direction. They also said to not lose sleep over it as whatever convention (yes, pun) one uses, as long as your consistent your circuits can still be made to work correctly. At least sometimes.  ;)

polymorph

I still agree with you. I started learning electronics quite young. I can't really remember not being interested in electronics, although I do remember deciding that I wanted a career in electronics. I think I was 9, which would have been 1970/71. Not that I didn't study it before then...

I remember wondering why everyone didn't just describe things the way they are. If electrons are the charge carriers, then say so. If positive ions are the charge carriers in a different part of the circuit, then say so.
Steve Greenfield AE7HD
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retrolefty

#39
Feb 07, 2014, 04:05 pm Last Edit: Feb 07, 2014, 04:08 pm by retrolefty Reason: 1
A though came to me overnight on this topic.

There is a reason they call this field "electronics". It's because it's all about the electron and it's behavior.


Grumpy_Mike


Well my point is that 'conventional current flow direction' has no useful place in the teaching of electronics, it adds no value and only confuses. Just teach that current flows in DC circuits from negative to positive via electrons.


Well I would strongly disagree with you and so would most of the rest of the world because conventional current is taught and it has no detrimental effects on the understanding of anything.
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They just guessed wrong about the direction of flow.

Did you not read my post? It was not a guess, it was a reasoned argument from the phenomena of electrolysis. It actually is the right direction for positive charge carriers, which was the effect being observed.

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Well in this case I agree with the derp, 'conventional current flow' is a myth and unsubstantiated no matter how it is spun.

It is not a myth.
Electrons are just as made up as holes are made up. One is no more real than the other. Each can be described in terms of the other, each are equally as valid.

There is a phenomena of electric flow. Depending on the material it is flowing in one of the concepts of electrons or holes describe what is happening simply, the other still works but is way more complicated.

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and a lot of the 20 somethings don't even want to hear about "conventional" current flow.

So not actually scientists are they. There are lots of things that 20 somethings don't want to know about, don't take that as any sort of evidence of anything.

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What is actually flowing in a DC circuit depends. Through a wire, electrons. Through a battery (parts of it), the majority charge carriers are positively charged ions. Negatively charged electrons are pulled to the more positively charged parts of the circuit (battery, generator, etc) and if positively charged ions are flowing, they move towards the more negatively charged parts.

No .... what is flowing is charge, depending how you define that charge defines the direction in which it flows.


There is a reason they call this field "electronics". It's because it all about the electron and it's behavior.

:) yes but that is only a convention guess  :P

retrolefty

#41
Feb 07, 2014, 04:49 pm Last Edit: Feb 07, 2014, 04:51 pm by retrolefty Reason: 1
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It is not a myth.
Electrons are just as made up as holes are made up. One is no more real than the other. Each can be described in terms of the other, each are equally as valid.


Good morning GM. I covered this earlier.  Electrons are not 'made up' objects, They are one of several components that make up the structure of a atom and it's the electrons in the outer valence orbit that allows for current to flow among atoms. What real physical object is a hole again? Again not talking about 'black holes'.  ;)


mirith

The physical representation of a hole is a positively charged atom missing an electron that it normally would have in equilibrium.  Its basically a vacuum of electrons.  If that is not a real world thing to you, then we will have to agree to disagree on things that exist in the real world.  In terms of Hole-Flow theory, I have completely ignored it, as it sounds like a silly justification. 

While I think we all agree that there is no major issue to performing EE work using Conventional vs Electron Flow, I do think most major US universities still teach Conventional over Electron.  Its the same reason the US still uses imperial units, its hard to make large numbers of people change.  I'd be curious of the statistics behind what major universities teach what, and what percentages, etc, but a quick Google search turns up little.  I was surprised to hear that the USAF teaches electron flow.

Grumpy_Mike

Hi,
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Electrons are not 'made up' objects,

Yes they are. They are made up to describe the phenomena we see. They are a model. They are a very successful model and they can be used in a great many number of things, but that does not change the fact that the idea has been made up.  
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hey are one of several components that make up the structure of a atom

Yes and they are made up as well, again they are very successful at describing what things we see. But never the less they are made up, just like all of physics. They carry credence as long as they continue to be able to describe what we see. When that limit is reached we modify the model  or make up a new one. That is how science progresses.

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t's the electrons in the outer valence orbit

Now orbits of an electron are made up as well. In this case we know that this does not describe what is actually going on, so the electron orbit model is not a full description of what happens in a atom. However, it is a good enough model to be useful in a number of limited circumstances so it is still kept around. However, we know that an electron does not orbit an atom, we have known this since the 30's. The negative charge around an atom is smeared over the whole radius of what your model calls the orbit. So there are lots of things that you are thinking are "real" that are only models. These models approach reality but no scientist would claim they describe things perfectly.

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What real physical object is a hole again?

A deficient electron.
Not real enough for you?  ;)
I can assure you physics gets a lot more unreal than that without batting an eyelid.
You can weight a deficient electron and come up with a positive number. This means that electrons in these circumstances have negative mass. Is that real? It is about as real as a hole having a positive one.

Anyway why do you think it matters what direction you think current is flowing in? It is normally brought up by beginners trying unsuccessfully to get to grips with a series circuit. They say things like "if the current first flows through the resistor then it will use all it's energy on this resistor first".

Electricity is a model for what we see. You can construct that model round electron flow or hole flow it matters not because both are going on at the same time but it is a symmetrical situation so you can safely ignore one of them. It doesn't matter which one.


JimboZA

Interestingly, the OP has been completely silent in this pissing contest arcane discussion since the thread started  2 1/2 days ago.
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