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Using Arduino => General Electronics => Topic started by: AppleAssassin on Feb 05, 2014, 01:38 am

Title: Flow of electricity - Simple Circuits
Post by: AppleAssassin on Feb 05, 2014, 01:38 am
Okay, so I have a class for my third year software engineering at university and have to do things with arduino which is fine however:

I took physics in high school and got a B however recently I just can't get my head around circuits   :| The whole flow of current vs the flow of electrons, positive to negative, negative to positive etc. But I just can't get my head around WHY it doesn't matter which side of a simple circuit the resistor is on. I'd like a good analogy, because currently I'm imagining a sort of road with cars as electrons and when they get to the resistor they slow down, but when they come back to the power source they speed up again. I just don't get how they can come up to the LED, without having gone through the resistor, out of the battery and not damage it. I'm so confused.

However upon just typing that paragraph I thought of a new analogy, still with cars though. Is it more like a traffic jam? Like when the circuit is completed the "cars" start to move but are held up by the "cars" in front of them?
Title: Re: Flow of electricity - Simple Circuits
Post by: polymorph on Feb 05, 2014, 03:29 am
The much maligned water analogy works, if you don't try to take it too far.

If you put a restriction in a pipe, the water slows down on both sides of the restriction. But the pressure on the downstream side is a lot less.

If you take the restriction out and put it back in the other way, nothing changes. The upstream side has more pressure, but the same number of gallons per minute flows on each side.

The car analogy does not work because cars are a compressible fluid. Water is an incompressible fluid, and if you don't go to extremes, electricity mostly acts like an incompressible fluid. Again, don't try to take the analogy too far.
Title: Re: Flow of electricity - Simple Circuits
Post by: Grumpy_Mike on Feb 05, 2014, 04:50 am
Forget trying to work out electron flow it only confuses. Concentrate on current flow from positave to negitave . What is flowing? It is charge. Just think of it as electric charge that flows.
It flows in a circuit, that means it circulates so it is not important what component is encountered first because all components have to be gone through in a compleat lap of a circuit.
Title: Re: Flow of electricity - Simple Circuits
Post by: cjdelphi on Feb 05, 2014, 05:09 am
With your car analogy. ..

Think of a resistor as a speed limit, the road (single series circuit anyway) is the wire, the cars all travel at the speed set by the total resistance...

The speed limit affects all cars on that one road before and after (single series circuit) so if we have 2 resistors on the same road combine the value and the resistance equal how fast the cars travel, and they all move at the same speed, decrease the resistance the faster the cars go, on both sides of the resistor.

Now stick an led into the mix, the led will consume (providing threshold voltage met) everything you give it, too many cars/current/electrons will blow it, so you add a speed limit to control the current.. so remember that the resistor slows the electrons down regardless where you place it in a single series circuit.

Title: Re: Flow of electricity - Simple Circuits
Post by: AiRgeek on Feb 05, 2014, 06:07 am
I hope this helps to clear up current flow, for reference purpose

Quote

Conventional Current assumes that current flows out of the positive terminal, through the circuit and into the negative terminal of the source.

Electron Flow is what actually happens and electrons flow out of the negative terminal, through the circuit and into the positive terminal of the source.


Ref: http://www.mi.mun.ca/users/cchaulk/eltk1100/ivse/ivse.htm# (http://www.mi.mun.ca/users/cchaulk/eltk1100/ivse/ivse.htm#)

In electrical engineering i.e. for circuit analysis, it is common to adopt  Conventional Current flow.

I am not sure what you mean by "but when they come back to the power source they speed up again", I think looking into The Mesh Current Method of circuit analysis could help to clear things up a bit.
http://www.allaboutcircuits.com/vol_1/chpt_10/3.html (http://www.allaboutcircuits.com/vol_1/chpt_10/3.html)
Title: Re: Flow of electricity - Simple Circuits
Post by: dlloyd on Feb 05, 2014, 08:39 am
Analogies are great ... the more the better!
Voltage <--> Pressure
Resistance  <--> Pipe Size
Amps <--> flow rate (of charge or force)
Power <--> Speedometer
Energy <--> Odometer
Visual analogy of electricity at work <--> Kinetic Pendulum

I thought check a few videos of kinetic pendulums and after seeing a few, here's a variation that's quite amazing. This (in my opinion) seems to demonstrate the truth about wave forms, where a square wave is actually an infinite series of sine wave harmonics added together. The square wave would be when the pendulums are moving in one line (end to end). Or possibly it demonstrates this: "It has been found that any repeating, non-sinusoidal waveform can be equated to a combination of DC voltage, sine waves, and/or cosine waves at various amplitudes and frequencies".

Repeating Waveforms <-->
http://www.youtube.com/watch?v=yVkdfJ9PkRQ





Title: Re: Flow of electricity - Simple Circuits
Post by: JimboZA on Feb 05, 2014, 08:52 am
And whichever way it really flows, the key principles are those of Kirchoff:

Title: Re: Flow of electricity - Simple Circuits
Post by: dave-in-nj on Feb 05, 2014, 01:03 pm
I think one part that might be missing is relativity.

the electron entering the LED can only move through the LED as fast as the flow allows.  the resistor limits the flow.

for the classic resistor and led, one way to look at it is a pipe,  the resistor limits the speed (voltage) from the point the individual pipe is connected to power all the way to the point it is connected to something on the other side.

if they were beans, then you could count how many went into the pipe, or in the middle or out the other end.   it would not matter.

back to relativity.   if you need 20 beans, you calculate the resistor.  you get 20 beans.

no where does the amount of beans available ever come into play.  it could be a cup you are pouring in, or it could be a 5 pound bag, or a cargo ship at the dock.    if your LED wants 20 beans, your resistor is selected, you only ever get 20 beans in that pipe.

so, if your power is 9 volts or 8,000 volts, the resistor only allows 20 beans to pass. 

Many people try to think the available quantity has any effect.   

another idea might be if you take a cup to the water fountain and try to fill it.  all you care about is how full the cup is.
next use a garden house.  were you able to fill the cup any more ?
now, dip it in the swimming pool.  could you fill it more ?
now go to the ocean, could you fill it any faster or and fuller ?

what is available has no bearing on what you use.
Title: Re: Flow of electricity - Simple Circuits
Post by: JimboZA on Feb 05, 2014, 01:06 pm
Quote
the resistor only allows 20 beans to pass.


.... per unit time.

Title: Re: Flow of electricity - Simple Circuits
Post by: polymorph on Feb 05, 2014, 02:44 pm
OK, this is getting confusing even to me.

Voltage is not power. Current flow is not speed. Given a specific flow of current (1A = 6.24x10^18 electrons/sec past a point), the speed of the electrons in a thin wire are much faster than the speed of the same current flow in a thick wire. Just as the water shooting out the nozzle on the end of a garden hose is moving very quickly, but the exact same amount of gallons per minute in the big pipe feeding your block is very slow.

Imagine a big loop of pipe connected to a pump we'll call V1, with two valves inline, we'll call the valves R1 and R2. The system does not leak.

Open R1 partway, and R2 partway. With the pump running and creating a constant pressure of water between its inlet and outlet, can you see that both valves inline reduce water flow to less than what it would be if there were only one valve? Can you see any reason it would matter which valve is "first"?
Title: Re: Flow of electricity - Simple Circuits
Post by: mirith on Feb 05, 2014, 04:13 pm
Physicists use Electron Flow
Real people use Current/Traditional/Ben Franklin Flow
I would try and ignore Electron Flow unless you are specifically wanting to get deep into the physics aspect of it.  Or you are trying to do Semi-conductor/material science.
Title: Re: Flow of electricity - Simple Circuits
Post by: Grumpy_Mike on Feb 05, 2014, 05:12 pm
Quote
Physicists use Electron Flow

No they don't.
They use charge flow depending upon what is the majority carriers in the substance they are studying.

Quote
the speed of the electrons in a thin wire are much faster than the speed of the same current flow in a thick wire.

No the speed of electrons is always about the same irrespective of the wire. That speed is only about 30 miles per hour so it is not very fast.

Quote
so, if your power is 9 volts or 8,000 volts, the resistor only allows 20 beans to pass. 

Total rubbish.

Quote
back to relativity.   if you need.......

Relativity concerns traveling at close to the speed of light, nothing to do with this argument.

Title: Re: Flow of electricity - Simple Circuits
Post by: Teslaspigeons on Feb 06, 2014, 03:51 am

Physicists use Electron Flow


Physicists use the majority charge carrier which depends on the material.  It can be electrons or it can be holes moving through a lattice. 
Title: Re: Flow of electricity - Simple Circuits
Post by: retrolefty on Feb 06, 2014, 02:08 pm

Physicists use Electron Flow
Real people use Current/Traditional/Ben Franklin Flow
I would try and ignore Electron Flow unless you are specifically wanting to get deep into the physics aspect of it.  Or you are trying to do Semi-conductor/material science.


From my experience that is exactly backwards. I was taught in military electronic training that EE physics teaches and uses the concept of 'conventional' current flowing being positive to negative while we were taught to use that electron/current flows negative to positive. It's an old argument/preference dating back forever to the early discovers of electricity. The physicists, once aware of their basic error invented 'hole flow' so they could continue to believe (in error) that current flows from positive to negative.

Take your side of the 'argument', but just stay consistent and your circuits will still function. It wouldn't be a problem except the physicists got to define which way the arrow points in semiconductors symbols so as to maintain their original error in defining current flow direction, so all our schematic drawings are wrong.  ;)
Title: Re: Flow of electricity - Simple Circuits
Post by: polymorph on Feb 06, 2014, 02:21 pm
Quote
The physicists, once aware of their basic error invented 'hole flow' so they could continue to believe (in error) that current flows from positive to negative.


I don't even know where to start with how wrong this is.

Title: Re: Flow of electricity - Simple Circuits
Post by: retrolefty on Feb 06, 2014, 02:56 pm

Quote
The physicists, once aware of their basic error invented 'hole flow' so they could continue to believe (in error) that current flows from positive to negative.


I don't even know where to start with how wrong this is.




Bring it on.  :D Please be aware that the U.S. Air Force has drones available if needed.
Title: Re: Flow of electricity - Simple Circuits
Post by: mirith on Feb 06, 2014, 03:10 pm


Physicists use Electron Flow
Real people use Current/Traditional/Ben Franklin Flow
I would try and ignore Electron Flow unless you are specifically wanting to get deep into the physics aspect of it.  Or you are trying to do Semi-conductor/material science.


From my experience that is exactly backwards. I was taught in military electronic training that EE physics teaches and uses the concept of 'conventional' current flowing being positive to negative while we were taught to use that electron/current flows negative to positive. It's an old argument/preference dating back forever to the early discovers of electricity. The physicists, once aware of their basic error invented 'hole flow' so they could continue to believe (in error) that current flows from positive to negative.

Take your side of the 'argument', but just stay consistent and your circuits will still function. It wouldn't be a problem except the physicists got to define which way the arrow points in semiconductors symbols so as to maintain their original error in defining current flow direction, so all our schematic drawings are wrong.  ;)


No, EE teachers, (at least in the US and at my my university), teach conventional flow.  My various physics teachers over the years would teach either conventional or Electron flow depending on how spiteful they are.  Physics are entirely willing to change their viewpoint for correctness.  Its the engineers who don't due to practicality. 

As mentioned, as long as you are consistent, it should not matter, though your schematic symbols make significantly less sense with electron flow (Look at a Diode, with a triangle with the point in the direction current can flow with conventional).
Title: Re: Flow of electricity - Simple Circuits
Post by: cjdelphi on Feb 06, 2014, 03:21 pm

Quote
The physicists, once aware of their basic error invented 'hole flow' so they could continue to believe (in error) that current flows from positive to negative.


I don't even know where to start with how wrong this is.




Which part?

In the past they believed the flow to be from positive to negative.. until it was proven untrue.

Title: Re: Flow of electricity - Simple Circuits
Post by: Grumpy_Mike on Feb 06, 2014, 03:23 pm

From my experience that is exactly backwards. I was taught in military electronic training that EE physics teaches and uses the concept of 'conventional' current flowing being positive to negative while we were taught to use that electron/current flows negative to positive. It's an old argument/preference dating back forever to the early discovers of electricity. The physicists, once aware of their basic error invented 'hole flow' so they could continue to believe (in error) that current flows from positive to negative.

Well do you know how this "mistake" was made? It was from the observation that in electroplating the metals end up being removed from the anode to the cathode. So the reasoning was that the metal was carried by the electricity from the anode to the cathode, not such a daft idea, but in fact with hindsight it was wrong.
Then by studying cathode rays it was realised that electrons in the gas were the carriers of charge. However that only applied to gasses where electrons were the majority carriers.
As theory advanced and semiconductors were explored materials were found that showed charge being transferred from positive to negative just like originally thought. To explain this the concept of the hole was created having a positive charge and incidentally under the right conditions also a positive mass. A hole can be considered as the absence of an electron in the same way you can think about the dynamics of a bubble in soda rather than thing about it as the absence of soda and having to work out the movement of all of the soda round this absence.

So in the end it did not matter at all what way you considered electricity to flow because it flowed in a different direction depending on the material it was flowing in. Therefore there was no need to change anything as there is an equally compelling case for either direction.

Quote
I was taught in military electronic training ......

Yes and they would know I suppose? Sounds like a bit of macho spin on the tale.
Title: Re: Flow of electricity - Simple Circuits
Post by: retrolefty on Feb 06, 2014, 04:40 pm


From my experience that is exactly backwards. I was taught in military electronic training that EE physics teaches and uses the concept of 'conventional' current flowing being positive to negative while we were taught to use that electron/current flows negative to positive. It's an old argument/preference dating back forever to the early discovers of electricity. The physicists, once aware of their basic error invented 'hole flow' so they could continue to believe (in error) that current flows from positive to negative.

Well do you know how this "mistake" was made? It was from the observation that in electroplating the metals end up being removed from the anode to the cathode. So the reasoning was that the metal was carried by the electricity from the anode to the cathode, not such a daft idea, but in fact with hindsight it was wrong.
Then by studying cathode rays it was realised that electrons in the gas were the carriers of charge. However that only applied to gasses where electrons were the majority carriers.
As theory advanced and semiconductors were explored materials were found that showed charge being transferred from positive to negative just like originally thought. To explain this the concept of the hole was created having a positive charge and incidentally under the right conditions also a positive mass. A hole can be considered as the absence of an electron in the same way you can think about the dynamics of a bubble in soda rather than thing about it as the absence of soda and having to work out the movement of all of the soda round this absence.

So in the end it did not matter at all what way you considered electricity to flow because it flowed in a different direction depending on the material it was flowing in. Therefore there was no need to change anything as there is an equally compelling case for either direction.

Quote
I was taught in military electronic training ......

Yes and they would know I suppose? Sounds like a bit of macho spin on the tale.


No spin GM, they explicitly covered this in the first couple of weeks of training in the Fundamental DC segment. So while some may not accept it all as fact, it's how they decided to deal with the concept and try to explain a seemingly conflicting definition of what direction does current flow in a DC circuit. And yes they did use some water piping analogies in helping to teach basic ohm's law.  ;)
Title: Re: Flow of electricity - Simple Circuits
Post by: retrolefty on Feb 06, 2014, 04:47 pm
Quote

So in the end it did not matter at all what way you considered electricity to flow because it flowed in a different direction depending on the material it was flowing in. Therefore there was no need to change anything as there is an equally compelling case for either direction.


That seems lame to me. Circuits are a combination of components and conductors. Surely something can not be flowing in one direction through a transistor say emitter to collector and somehow reverse direction as it hits the wires going to and from the transistor. There seems to be no questions that something physical is flowing in only one direction in a DC circuit, which is it that is physically moving? 'Holes' are not physical things but rather a lack of something physical.

My opinion is that 'holes' are a human invention, not unlike religions are, not a physical reality. It's a journey into creative human spin.  ;) 

Title: Re: Flow of electricity - Simple Circuits
Post by: mirith on Feb 06, 2014, 05:06 pm

Quote

So in the end it did not matter at all what way you considered electricity to flow because it flowed in a different direction depending on the material it was flowing in. Therefore there was no need to change anything as there is an equally compelling case for either direction.


That seems lame to me. Circuits are a combination of components and conductors. Surely something can not be flowing in one direction through a transistor say emitter to collector and somehow reverse direction as it hits the wires going to and from the transistor. There seems to be no questions that something physical is flowing in only one direction in a DC circuit, which is it that is physically moving? 'Holes' are not physical things but rather a lack of something physical.

My opinion is that 'holes' are a human invention, not unlike religions are, not a physical reality. It's a journey into creative human spin.  ;)  




Holes are a Material Science concept.  Basically it is the lack of an electron where there should be one.  In some materials (mainly a subset of semi-conductors I believe, but I could very well be wrong, this was from a class a few years ago), electrons move by filling other nearby vacant holes.  Thus the 'hole flow'  This is however less efficient than conductors, which work by free electrons moving around freely, rather than moving from vacant hole to vacant hole.  This is what makes Gold and Copper good conductors, while (I think) Carbon or Silicon can be a very good or bad one, depending on what you are doing and how it is doped.

I'm actually fairly surprised the US Military teaches Electron flow.  Its good to know on a material science/semi-conductor level, but I never considered it practical for common EE practices (See Designing, building and troubleshooting circuits).  Its good to know that it exists, why it exists and that it is the actual physical way things happen, but it again never seemed practical to me.
Title: Re: Flow of electricity - Simple Circuits
Post by: Grumpy_Mike on Feb 06, 2014, 06:35 pm

'Holes' are not physical things but rather a lack of something physical.

Well if something carries charge and has positive mass then in my book it is a good candidate for existing as anything else. The idea of electrons as little bullets is equally as made up.
The thing is that the whole world is stuff we have made up, we have made up the concept electron in just the same way we made up the concept of the hole. We do experiments, do the math and then make up something that fits those two.
We have done well with the made up charge carriers, it allows us to understand how to make transistors.

Quote
Surely something can not be flowing in one direction through a transistor say emitter to collector and somehow reverse direction as it hits the wires going to and from the transistor.

Now you are not grasping the fact that the something is not the same when the direction changes. In metals then electrons are the majority charge carriers but there are still holes. In P type semiconductors where the majority charge carriers are holes there are still electrons. So in ALL circuits electrons flow in one direction and holes in the other. Both are made up and ultimately it makes not a jot of difference which you chose to consider as long as you are consistent.
Title: Re: Flow of electricity - Simple Circuits
Post by: retrolefty on Feb 06, 2014, 06:50 pm


'Holes' are not physical things but rather a lack of something physical.

Well if something carries charge and has positive mass then in my book it is a good candidate for existing as anything else. The idea of electrons as little bullets is equally as made up.
The thing is that the whole world is stuff we have made up, we have made up the concept electron in just the same way we made up the concept of the hole. We do experiments, do the math and then make up something that fits those two.
We have done well with the made up charge carriers, it allows us to understand how to make transistors.

Quote
Surely something can not be flowing in one direction through a transistor say emitter to collector and somehow reverse direction as it hits the wires going to and from the transistor.

Now you are not grasping the fact that the something is not the same when the direction changes.  In metals then electrons are the majority charge carriers but there are still holes. In P type semiconductors where the majority charge carriers are holes there are still electrons. So in ALL circuits electrons flow in one direction and holes in the other. Both are made up and ultimately it makes not a jot of difference which you chose to consider as long as you are consistent.


There does not need to be the concept of a hole to support electron flow in metals as it's perfectly possible that a atom with an extra electron (negatively charged atom) in it's valence orbit jumps to an adjacent neutrally charged atom which then becomes negatively charged and the prior atom returns to become a neutral charged atom, no hole required to support this 'electron jumping' in the direction of negative to positive potential. Even in the case of semiconductors it's the electrons that are moved in the direction of 'true' current flow. In a moving car with no ambient wind one may seem to feel that the wind is moving from front to rear of  a moving car if you stick your head out the window, however it's still the car (an electron if you will) that is actually moving in the opposite direction of this 'apparent wind'.
Title: Re: Flow of electricity - Simple Circuits
Post by: Grumpy_Mike on Feb 06, 2014, 07:04 pm
Quote
There does not need to be the concept of a hole to support electron flow in metals

This is true but the fact remains that the flow of charge in a metal can be modeled by the concept of holes, it is just harder. In exactly the same way as you can describe the flow of charge in a P-type semiconductor by using the concept of electrons, it is just that it is harder than using holes. So we use what ever concept is easier to cope with.

Quote
Even in the case of semiconductors it's the electrons that are moved in the direction of 'true' current flow.

I think that encapsulates your problem. There is no "true" direction of current. It is that misconception probably that is driving the military education.
Current is charge flow, there is no true direction. If you consider positive charge carriers it is one way, if you consider negative charge carriers it is the other way. Each is an exact mirror complement of the other and both are something that us humans have made up.
Title: Re: Flow of electricity - Simple Circuits
Post by: retrolefty on Feb 06, 2014, 07:14 pm

Quote
There does not need to be the concept of a hole to support electron flow in metals

This is true but the fact remains that the flow of charge in a metal can be modeled by the concept of holes, it is just harder. In exactly the same way as you can describe the flow of charge in a P-type semiconductor by using the concept of electrons, it is just that it is harder than using holes. So we use what ever concept is easier to cope with.

Quote
Even in the case of semiconductors it's the electrons that are moved in the direction of 'true' current flow.

I think that encapsulates your problem. There is no "true" direction of current. It is that misconception probably that is driving the military education.
Current is charge flow, there is no true direction. If you consider positive charge carriers it is one way, if you consider negative charge carriers it is the other way. Each is an exact mirror complement of the other and both are something that us humans have made up.


I hear what you are saying, there are three charge states an atom can posses, negative, positive, or neutral and electron movement results in two of these three states potential difference allowing among adjacent atoms. But back to the fact that an electron is a real object that science does acknowledge is a real physical object just as are neutrons and protons are, as well as sub-atomic particles discovered like quarks and the such. While I'm no scientist for sure I've never come across  them mentioning a hole being among the other real physical objects. Unless you claim that really small black holes are flowing inside transistors.  ;)

Holes are a religion.   ;)
Title: Re: Flow of electricity - Simple Circuits
Post by: polymorph on Feb 06, 2014, 07:29 pm
I think you have a misconception that any physicist or EE thinks that holes exist. It is merely a model used to make visualizing what is going on in semiconductors easier.
Title: Re: Flow of electricity - Simple Circuits
Post by: retrolefty on Feb 06, 2014, 08:24 pm

I think you have a misconception that any physicist or EE thinks that holes exist. It is merely a model used to make visualizing what is going on in semiconductors easier.


I agree that it's a model that certainly worked to support the impressive development of solid-state electronics I have seen in my lifetime (67 years old in my case). However I have based my comments on the fundamental question of what direction does current flow in all DC circuits, and what is actually moving to support that flow?
Title: Re: Flow of electricity - Simple Circuits
Post by: polymorph on Feb 06, 2014, 08:27 pm
In that case, it depends... ;') Charge flows. Holes are merely a model, a simplification. Because it is far too complicated to use the Standard Model to calculate everything.
Title: Re: Flow of electricity - Simple Circuits
Post by: retrolefty on Feb 06, 2014, 08:31 pm

In that case, it depends... ;') Charge flows.
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.
Holes are merely a model, a simplification. Because it is far too complicated to use the Standard Model to calculate everything.
So do you agree that holes are not real, but rather just a means to explain how solid-state material supports current flow?
Title: Re: Flow of electricity - Simple Circuits
Post by: polymorph on Feb 06, 2014, 08:49 pm
Quote
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.

Quote
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 (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 (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.
Title: Re: Flow of electricity - Simple Circuits
Post by: polymorph on Feb 06, 2014, 09:00 pm
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.

Title: Re: Flow of electricity - Simple Circuits
Post by: retrolefty on Feb 07, 2014, 12:26 am

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
Title: Re: Flow of electricity - Simple Circuits
Post by: polymorph on Feb 07, 2014, 12:50 am
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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.
Title: Re: Flow of electricity - Simple Circuits
Post by: polymorph on Feb 07, 2014, 12:52 am
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.
Title: Re: Flow of electricity - Simple Circuits
Post by: retrolefty on Feb 07, 2014, 01:06 am
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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.




Title: Re: Flow of electricity - Simple Circuits
Post by: polymorph on Feb 07, 2014, 01:11 am
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 (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.
Title: Re: Flow of electricity - Simple Circuits
Post by: retrolefty on Feb 07, 2014, 01:53 am
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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.  ;)
Title: Re: Flow of electricity - Simple Circuits
Post by: polymorph on Feb 07, 2014, 03:27 am
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.
Title: Re: Flow of electricity - Simple Circuits
Post by: retrolefty on Feb 07, 2014, 04:05 pm
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.

Title: Re: Flow of electricity - Simple Circuits
Post by: Grumpy_Mike on Feb 07, 2014, 04:09 pm

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
Title: Re: Flow of electricity - Simple Circuits
Post by: retrolefty on Feb 07, 2014, 04:49 pm
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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'.  ;)

Title: Re: Flow of electricity - Simple Circuits
Post by: mirith on Feb 07, 2014, 05:25 pm
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.
Title: Re: Flow of electricity - Simple Circuits
Post by: Grumpy_Mike on Feb 07, 2014, 05:34 pm
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.

Title: Re: Flow of electricity - Simple Circuits
Post by: JimboZA on Feb 07, 2014, 05:57 pm
Interestingly, the OP has been completely silent in this pissing contest arcane discussion since the thread started  2 1/2 days ago.
Title: Re: Flow of electricity - Simple Circuits
Post by: Grumpy_Mike on Feb 07, 2014, 06:11 pm

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

Well his original problem was nothing to do with what direction current flows, it was in understanding a serial circuit. He said:-
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But I just can't get my head around WHY it doesn't matter which side of a simple circuit the resistor is on.

I think that was answered long ago. In fact the question troubling him has nothing to do with the direction of the flow of current. The fact that he thought it did was the major part of his problem.
Title: Re: Flow of electricity - Simple Circuits
Post by: retrolefty on Feb 07, 2014, 06:56 pm


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

Well his original problem was nothing to do with what direction current flows, it was in understanding a serial circuit. He said:-
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But I just can't get my head around WHY it doesn't matter which side of a simple circuit the resistor is on.

I think that was answered long ago. In fact the question troubling him has nothing to do with the direction of the flow of current. The fact that he thought it did was the major part of his problem.



Well to fair to my side the OP did also state/ask in his original post:

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The whole flow of current vs the flow of electrons, positive to negative, negative to positive etc.


That kind of sums up the majority of the comments in this thread, no?
Title: Re: Flow of electricity - Simple Circuits
Post by: cjdelphi on Feb 07, 2014, 09:34 pm

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


"Superior" posts like this one always makes me think that the poster feels left out...