Does Voltage Work Against Electron Movement?

[jartsa]

jartsa: yes, and how would you then interpret this:

VOLTS x COULOMBS = JOULES It takes energy to push some charge against the voltage pressure

here it doesn't say 'against resisting force' but 'against voltage pressure'? This is, to my understanding, two completely different things.

I interpret it this way:

It takes energy to push some charge to where the charge is unwilling to go, like for example into a place filled with similar charges.And here are some additional thoughts:

A negative charge wants to go from the minus electrode of a battery to the plus electrode. It takes energy to push the charge the other direction, from plus to minus. Battery happens to push electrons from plus to minus, inside the battery.

In a circuit consisting of a battery and a resistive wire, electron has the most energy at the negative electrode. If electron moves from there into either one of the two possible directions, its energy decreases.

Charges are sensitive to voltage pressure, whatever voltage pressure means. If a charge is effected by a voltage pressure and the charge is pushed, work is being done.
voltage = energy / charge

If a charge is effected by a voltage pressure and the charge moves by itself, work is being done by the charge.
voltage = energy / charge

 

[sophiecentaur]

sophiecentaur: I'm not asking for at metaphor, but a description.

jartsa: yes, and how would you then interpret this:

VOLTS x COULOMBS = JOULES It takes energy to push some charge against the voltage pressure

here it doesn't say 'against resisting force' but 'against voltage pressure'? This is, to my understanding, two completely different things.

You say you don't want a metaphor but that is a total metaphor. Volts are not pressure so you are starting with a metaphor in that phrase (the two terms just can't go together in a sentence that is self consistent). You may feel a bit defensive about that article - which I agree, is pretty good - but straying away from precise wording in an attempt to make things more acceptable (I don't use the word 'understandable') he has introduced just the sort of confusion that you have here. It can't be surprising when a when a fudge results in a fudge. You should not feel constrained to that article for ever. It has actually let you down in this. Don't throw it away though - this is a demonstration where multiple sources are always needed when you want to get to grips with things. Needless to say, the Maths approach will not let you down that this.

I can see your problem with the notion of charges 'struggling against a force' in a circuit. That problem arises because it's not a good way to look at it. You need to 'push' charges uphill when charging a battery. In the end, this will involve forcing them against the electric field - doing work against the field from the battery, to cause the chemical changes so using the idea of a force is fair enough - if you insist. But your thread title has the word "voltage" in it and voltage is energy. You also could say that you need to 'push' charges through a resistor - on the grounds that the energy dissipated can be likened to a force times a distance. But why not stick to the electrical world and say the energy is Charge times Volts?

You seem to have reached an impasse in this because you appear determined to get over this hurdle on your own terms. Why not take the accepted approach? You are not selling out if you do - you are opening up the next stage. I can guarantee that the new paradigm will only help you.

 

[Crazymechanic]

Just to add to my previous post and all that ahs been said after that.
I do think the modern society is actually very dumb and ignorant , let me explain why.Not because we would not know more than we knew some time ago rather because these days we are so interested and obsessed with the feelings that the modern day man needs to be a self contained little genius.Everybody's so " smart" and all knowing these days it sometimes makes me sick just by looking at them.Today it's more about your status than what you actually know , everyone wants to be lawyer , a bank director, a famous nobel prize winning scientist and a King of a country , I too had my classmates dream of big things meanwhikle they were so ignorant to simple learning stuff they couldn't tell their right from their left.
I apologize for telling you all this kjeldsmark but I do think sometimes it's very healty to realize how far one needs to go.
Pick up a thing and ask yourself are you strong enough to lift it if your not then put it back and come to try again after you had some training.I know some sports people , you see when it comes down to physical weight lifting you cannot find a side way with a great analogy or something similar you either have it or you don't , there is no way around.
Nobody comes perfect they all had to sweat and fight a lot before they had the power to do those things they do.

As for the thread topic.

jarsta said:

I interpret it this way:

this is the problem when we all come together and each of us interpret it this and that way.In this case i happen to agree with Sophie because if you have a 2+2=4 thing there is nothing to interpret anymore.your either right or your wrong.too bad but this isn;t psychology were we are being teached these days that everyone is right just in his own kind of way , I think such a teaching is destructive to the person hearing it as it leads one into thinking that no matter how wrong you get you can still be right.

And lastly , why are you so obsessed with the against voltage thing? All that matters is that you have voltage which is called PD.It's always some kind of voltage level with respect to a common point of no voltage or lower voltage or whatever different potential at some other point, like a PD across a resistor or across the terminals of a battery.There is no pressure before PD but after you apply a PD you can think of it as a force , the electric field that is associated with the PD which is responsible for " pushing" charges in the wire.Even though pushing may even not be the best word to use here.Now the part where you say that the electric field or voltage pushes against something is the tricky thing here , have you heard os superconductors? in other word say a copper wire at very low temperatures and the current can be there forever , theoretically , so there is no more loss or resistivity so the PD does't have to push agaisnt anything.
I believe the author using the against thing just wanted to show that a PD is doing work but he could have just said that when you have a PD it does a certain amount of work which is proportional to the amount of the PD or volts you have in agiven situation.

 

[sophiecentaur]

this is the problem when we all come together and each of us interpret it this and that way.In this case i happen to agree with Sophie because if you have a 2+2=4 thing there is nothing to interpret anymore.your either right or your wrong.too bad but this isn;t psychology were we are being teached these days that everyone is right just in his own kind of way , I think such a teaching is destructive to the person hearing it as it leads one into thinking that no matter how wrong you get you can still be right.

It's nice to know that. It may be a shame that life can't be lived without the Maths and Engineering - which aren't matters of opinion. But people who are posting on this forum are making use of other people's use of those disciplines so they can hardly dismiss them as a nuisance. There's a time and a place for such things and there are other times and places for culture and subjectiveness. The two things do, rather, run counter to each other and we are stuck with the dichotomy.

 

[Crazymechanic]

I think the problem is not in how much one understands something , it's rather that these days poeple want to pretend they understand things they have no clue about and maybe they even should't as it's not their deal and they don't even care about it.people like that fuzzy good little feeling inside when you ahev read something and you think oyu now know it ad you almoust go like yes I did it, but then one needs to be subjected to the harsh reality where he is proven or said wrong from a source of authority , we all need a point of reference to understand how far or how good or bad we are without that referance we are unable to understand anything.
I'm not good at maths either , when it comes to quantum mechanics and stuff like that I too understand better by analogies rather than numbers and equations.But atleas I'm fair to myself and don't call myself a quantum scientist.

On the other hand in no way do I want to discourage someone from learning into stuff even if he isn't good at maths , I believe that there can be people who can be good at physics and maybe evne discover something new without being very good at each particular thing ,overall it's not so muhc a question of how good your nature given talents are than a question of how really passionate and devoted one is in trying to reach for the top but not to be proud but for the fun of it and because he likes it that way.The results will show themselves.No hard work can go unseen.

 

[kjeldsmark]

I interpret it this way:

It takes energy to push some charge to where the charge is unwilling to go, like for example into a place filled with similar charges.


And here are some additional thoughts:

A negative charge wants to go from the minus electrode of a battery to the plus electrode. It takes energy to push the charge the other direction, from plus to minus. Battery happens to push electrons from plus to minus, inside the battery.

In a circuit consisting of a battery and a resistive wire, electron has the most energy at the negative electrode. If electron moves from there into either one of the two possible directions, its energy decreases.

Charges are sensitive to voltage pressure, whatever voltage pressure means. If a charge is effected by a voltage pressure and the charge is pushed, work is being done.
voltage = energy / charge

If a charge is effected by a voltage pressure and the charge moves by itself, work is being done by the charge.
voltage = energy / charge

Another question for you:

Again, regarding this sentence:

VOLTS x COULOMBS = JOULES It takes energy to push some charge against the voltage pressure

Does this sentence imply to you that the charges move because of the voltage force or in spite of the voltage force?

 

[Crazymechanic]

the charges move because of the electric field which is a direct result of voltage in a conductor.
PD is applied to a conductor and the charges are now pushed under force towards one or the other direction.before the voltage was applied the charges moved randomly with no net movement in a given direction so there was no voltage in the wire.
As you can tell something made them change that behaviour and move all in one direction to create a what's called current flow.So obviously there is a force involved here and that force is the electric field from the PD you applied to the wire.Is this good enough?

jarsta said

It takes energy to push some charge to where the charge is unwilling to go, like for example into a place filled with similar charges.

that is correct as alike charges repel but in a circuit with a PD , say a resistor connected to a battery you have the +ve and the - terminal , the + charges are wiling to go towards the - ones and to cancel out , so it's rather that a Potential difference is a situation where you separated charges using energy , and now once you have them separated you can use them to do work as they will want to get back to that equilibrium situation which is more commonly known as a empty battery.
Yet anyway the separated charges create a PD and the PD exerts a force on the charges in the conductor which makes them flow one or the other way , instead of zapping around randomly.
So a force is exerted by voltage to the charges if you like it better this way said.
But i wouldn't say theu have to move against anything after that, well they do encounter resistance and some other forces which can arise in devices like transformers etc like inductance but that is a whole different point , the basic thing is yu have voltage and you have it applied over a wire or circuit and you have current and the one is the result of the other.

Don't get mislead by bad wording, many poeple talk about cars and horsepower but few of them actually have a clue of what it actually means and some may even think that there are horses packed in the engine it doesn't change a thing.that is just a word used to describe certain units of power output.

 

[sophiecentaur]

Another question for you:

Again, regarding this sentence:

VOLTS x COULOMBS = JOULES It takes energy to push some charge against the voltage pressure

Does this sentence imply to you that the charges move because of the voltage force or in spite of the voltage force?

I see where you're coming from now. You can only make a charge move by providing a potential. (You can't poke it with a stick. Lol) so everything happens due to some imbalance of forces ( gradient of potential). Charges respond only to that. Descriptive words like 'with' and 'against' are what are getting in your way again. That's why the Sign in maths is so useful and it is consistent.

 

[jartsa]

Another question for you:

Again, regarding this sentence:

VOLTS x COULOMBS = JOULES It takes energy to push some charge against the voltage pressure

Does this sentence imply to you that the charges move because of the voltage force or in spite of the voltage force?

The answer to the question: In spite of the voltage force.Or if we want to say it correctly: In spite of the Coulomb force q*E (charge q times electric field E)

if we multiply force q*E with distance d we get q*E*d , which is energy
if we divide energy q*E*d by charge q, we get energy per charge which is voltage

 

[kjeldsmark]

This thing IS a question of wording. We 'agree' about these basic voltage things.

My question was regarding the specific sentence (which I'm translating), if it says (THE SENTENCE) that the charges move because OR in spite of the voltage pressure/force?

 

[kjeldsmark]

Jartsa: thanks. That was for me a concise explanation.

The sentence imply to you that the charges move - in spite of - the voltage force, but this is wrong isn't it? In reality they move BECAUSE of the voltage force right?

So the sentence is wrong?

 

[jartsa]

Jartsa: thanks. That was for me a concise explanation.

The sentence imply to you that the charges move - in spite of - the voltage force, but this is wrong isn't it? In reality they move BECAUSE of the voltage force right?

So the sentence is wrong?

That sentence seems correct to me: It does take energy to push a charge against an electric field E, over a voltage E*d.

But before and after that sentence Bill Beaty talks about charges that are NOT being pushed against an electric field, those charges are just "falling" at some terminal velocity in an electric field. That may be some kind of problem. I mean, the reader may become confused.

Actually, maybe it's not impossible that the writer got confused. So maybe there's an error in that sentence, although it's correct.

 

[kjeldsmark]

but the charge moves BECAUSE of the voltage force. When the sentence say the opposite - how can it be correct?

 

[Crazymechanic]

I think there is a problem here , jarsta told you about the coulomb force and yes indeed like charges repel, but here we are speaking about a conductor which only serves as the current carying medium , we are not talking about some free floating electrons in a vacuum chamber and even those align themselves to form a current path if a sufficiently high PD is applied, like in a CRT tube.

The conductor about which the OP speaks in a current carrying medium , the PD is the battery or any other power source introduced in the picture, the + charges want to get to the - charges whenever you form a path between the battery terminals , so what has that to do with the coulomb repulsion between electrons? We can observe that current is made in the wire when closing a circuit , and if that wire is cooled to low enough temperatures the current flow become resisatnce free.

Why would the charges need to be pushed agaisnt the very own field which made their flow possible in the first place?
You have a PD , you have a wire you connect the wire to form a cirucit , current flows , it doesn't flow against anything , would you say that a river flows against hill? The river flows from the highest place read potential to the lowest place /potential...

 

[sophiecentaur]

but the charge moves BECAUSE of the voltage force. When the sentence say the opposite - how can it be correct?

In the context you are seeing, it is not correct. It is badly put. The best thing you can do is just to let it go.
That statement would apply of you charged up a ball and we're moving it in the field between two plates. You would then be able to move the charge against the force caused by the field. In a purely electrical set up charges only move with the field. + charges will move to a lower electrical potential. To charge a battery, you need a source of higher PD than the battery is producing. Charge will then flow down into the battery - against the emf of the battery. The current that flows will be the difference between the two voltages / any resistance in the circuit. There! I even managed to get the word 'against' into my description.

 

[Crazymechanic]

Like sophie said , the argument you brought in is used in a purely electrostatic situation , charged objects repulsion etc, in a circuit PD moves charges and forms current

 

[kjeldsmark]

"Why would the charges need to be pushed agaisnt the very own field which made their flow possible in the first place?"

This is what I'm asking!

"VOLTS x COULOMBS = JOULES It takes energy to push some charge against the voltage pressure"

So, how do read this sentence (I'm not talking about ohms law in general but this specific sentence(which of cause is about ohms law)?

The sentence (FOR ME) says: it takes energy to push som charge (IN DIRECTION ONE) A G A I N S T the voltage pressure (DIRECTION TWO). In other words: it says that the same forcefield is pushing in two opposite directions. This makes NO sense to me!

 

[kjeldsmark]

I need to be absolutely sure that I don't misinterpret the English language with regards to the word "against" in this specific context.

 

[Crazymechanic]

just throw out that sentence , in the context were talking here it is wrong.
sophie already said that.
in a circuit there is no field agaisnt a field.There is a PD and a electric field which causes the charges to align and move in a given direction.there is no field against them.

in a transformer and other inductive devices there is a phenomenon called back EMF which acts against the change in current.that could be something closer , imagine in an inductor or a transformer when you first apply a PD , say turn on a switch imediately current rushes through the windings inducing magnetic flux in the core the induced flux creates a field opposite to that which induced it in the first place called back EMF.And even then your description doesn't apply in the way you think of it.
So I would say just let go that statement and rewrite it the way people explained it to you here.

Under normal conditions when you apply a PD to a circuit or whatever wire or etc there is a field and that field moves charges in a direction , there aren't two fields opposing each other , if there were there would be no charge movement,m the field would cancel out and it would be a static situation.Charges flow from higher potential to lower , the actual electrons if you care about them flow the other way but they both flow from one place towards another and there is a difference in potential between those two places , voltage doesn't go against voltage , that's like putting two battery + together, if they are at the same potential , guess what? Nothing happens.

 

[sophiecentaur]

Why do you insist on using the phrase "voltage pressure" when it is such a bad one? Also, you are making a pointless stand about the particular sentence which I have already said, doesn't make proper sense. It never will. Just because you read it in your favourite article in the whole world, it is not 'Gospel' but it is a fair article..
Just have the confidence to look at the whole thing another way round.
I don't think you can have read my last post because I did put the whole thing another way round to sort out your problem. To find which way a charge will flow, you just need to know which way is 'downhill'. Take a 3V battery, connect the neg terminal to Earth. Take a 6V battery, do the same. Connect the two + terminals together with a 1 Ohm resistor. Current will flow into the + terminal of the 3V battery against the 3V because there is a higher potential on the + terminal of the 6V battery. There will be (6-3)/1 Amps flowing (I=V/R)
The 3V acts against the 6V and the actual current flowing is regulated by the resistor.

You will notice that I never once mentioned Fields because they just do not help in any way to solve this problem. When you have taken things on board my way, and got some working knowledge of circuit calculations, then it might be a good time to investigate the Fields thing but you can spend y our whole life as an Electrical Engineer and only use the Field approach once or twice.

 

[kjeldsmark]

Thank you for trying to help me.

The reason I'm so opsessed with this expression 'against voltage pressure/force' is that it's used by so many professionals and people who I considder true experts. That's why I was/am thinking that the most reasonable explanation is that they mean something by this use of words which I don't see.

 

[sophiecentaur]

"so many"?
In what context?
I know a lot of seriously 'real' professionals and it's not the sort of thing they would be likely to say because it doesn't describe an electrical situation except in electrostatics, when other forces than directly electric ones come into play..
Are you sure this isn't a bit of displacement activity - putting off getting down to the real stuff? Huh?

'Professionals' talk in the correct way about Potential Difference, in any case. Voltages (emfs) can oppose one another, as Kirchoffs Second Law demonstrates but that is not what you are worrying about, I think.

 

[Crazymechanic]

I also said in earlier posts that there are situations in circuits where a situation similar to that you describe comes into play but first of all it's not defined the way you say it here and secondly the situation you are describing which is a fairly simple one , not even the sophies mentioned batteries rather a simple wire and some voltage on it and current running through it in such a situation there isn't anything opposing the original PD that creates the current in the wire.
So I would say in the situation you are talking about which is a basic current through a wire in a circuit situation nothing like you describe happens.


2+2=4 no matter is it said by a approved professional with a phd or a random stranger on the street you must be smart enough to see that sometimes truth can be said by anyone , I believe this is the case as I see no reason to disbelieve in sophies and other forum members arguments.

 

[jartsa]

but the charge moves BECAUSE of the voltage force. When the sentence say the opposite - how can it be correct?

Well ok I agree then. When reading a larger chunk of that text, then everything seems fine, except that one line sticks out, and there's a feeling that that one line is wrong.

 

[kjeldsmark]

And regarding 'learning style' I feel the same way as Mr. WJB:

"When I went into engineering school, I found it extremely odd that there were still no good explanations of bipolar transistors. Sure, there were detailed mathematical treatments. Just multiply the Base current by "hfe" to obtain the Collector current. Or, treat the transistor as a two-port network with a system of equations inside. Ebers-Moll and all that. But these were similar to black-box circuits, and none of them said HOW a transistor works, how can a small current have any effect on a larger one? And nobody else seemed curious. Everyone else in the class seemed to think that to memorize the equations was the same as learning concepts and gaining understanding of the device. (R. Feynman calls this the Euclidean or "Greek viewpoint;" the love of mathematics, as opposed to the physicists' "Babylonian viewpoint" where concepts are far more important than equations.) I'm a total Babylonian. For me, math is useless at the start, equations are like those black box Spice programs which might work great, but they don't tell you any details of what's happening inside a device in the real world. I can learn the math, but that just means I can run a "mental spice program" without needing any computer, and I still don't know how transistors work. First tell me what "Transistor Action" is all about. Show me animated pictures, use analogies. Only after I've attained a visual and gut-level understanding of something, only then is the math useful to me for refining it and adding all the details. However, for me the math alone is not a genuine explanation. Math is just a tool or a recipe, a crutch for those who want nothing except the final numerical result, and it certainly does not confer expert knowledge."

(http://amasci.com/amateur/transis.html)

 

[Crazymechanic]

Ok I understand your concern , I too am not a fan of mathematics mainly because I'm not that good at it.
Just to start this I want to say that the maths and the images and schematics in your head of how it works go hand in hand.I agree that it is good and even necessary to understand how does it work, but when you will need to make a physical device you will need some accurate measurements and sizes and dimensions and then mathematics will become involved.
Einstein realized that the atomic bomb is possible because he was a man of great mind yet it took much more physiscists and Oppenheimer as the leading one to calculate all the details to make a real physical example of that imagined bomb.

Second of all when we get down to the very small , say quantum level it becomes really really troubling to imagine and have a picture in your head about how it works , mainly because you can't see it , and every analogy every story about how atoms look or behave isn't a perfectly accurate picture it just goas as far as it can , and here maths also isn't the full answer it describes the interaction in detail but that doesn't make you suddenly an observer of atomic stuff.
I would say that in certain physics areas due to the fundamental limitatios of this world we live in no way is good enough to have this " gut" feeling you are talking about.

Why do you think there is something magical inside a transistor ? It's nt so much about smaller current controling larger one in a sense that you would think that you can move a big rock with a tiny little stick , its rather applying that small current into the right place.
let me make an analogy , maybe not a perfect one but from what i ca tell you like them.
imagine the BJT as a dam on a small river made of sand and soil.the damn keeps the river at a certain height so the water before the dam has a pretty high potential and that would be our collector current. Now the water even though could destroy the dam and wash it away doest do that it just sits there.Now take a little side stream and apply it to the right place inside them dam so that it washes away the soil and makes it wet , now the large water mass is able to push the dam aside and run free.

in a transistor bjt, the small base current isn't physically pushing the large collector current, it just makes the transistor conducting from a non conducting state and so the larger current can flow.

 

[sophiecentaur]

And regarding 'learning style' I feel the same way as Mr. WJB:

"When I went into engineering school, I found it extremely odd that there were still no good explanations of bipolar transistors. Sure, there were detailed mathematical treatments. Just multiply the Base current by "hfe" to obtain the Collector current. Or, treat the transistor as a two-port network with a system of equations inside. Ebers-Moll and all that. But these were similar to black-box circuits, and none of them said HOW a transistor works, how can a small current have any effect on a larger one? And nobody else seemed curious. Everyone else in the class seemed to think that to memorize the equations was the same as learning concepts and gaining understanding of the device. (R. Feynman calls this the Euclidean or "Greek viewpoint;" the love of mathematics, as opposed to the physicists' "Babylonian viewpoint" where concepts are far more important than equations.) I'm a total Babylonian. For me, math is useless at the start, equations are like those black box Spice programs which might work great, but they don't tell you any details of what's happening inside a device in the real world. I can learn the math, but that just means I can run a "mental spice program" without needing any computer, and I still don't know how transistors work. First tell me what "Transistor Action" is all about. Show me animated pictures, use analogies. Only after I've attained a visual and gut-level understanding of something, only then is the math useful to me for refining it and adding all the details. However, for me the math alone is not a genuine explanation. Math is just a tool or a recipe, a crutch for those who want nothing except the final numerical result, and it certainly does not confer expert knowledge."

(http://amasci.com/amateur/transis.html)

I have to say that William Beatty and / or his tutors must just have been out of their depth about the mechanism which makes a transistor work. Of course there is a 'good' (accurate) description in many textbooks. The point is that the description cannot be reduced to a trivial level whilst remaining accurate. How is that 'unsatisfactory'? Life is not full of simple solutions to all problems. If someone can't understand the full description then they are either limited by the level of their basic ability or by how much they are prepared to work at it. (Like weight lifting and triathlons).
That statement reflects either a sloppy attitude or an over estimate of his understanding of the topics he is applying to. It's not a matter of 'the Maths of the Ideas'. You need both, if you want to understand advanced Science to a level where you can predict and synthesise usefully. If you didn't need the Maths, then you could get a higher Physics degree on the strength of what they tell you on the TV Science programmes.
Do you really believe that this computer you are using, at the moment, was made to work by people who just waved their arms about and had a 'comfortable' feeling that they grasped how solid state devices work? Maths is not "just a crutch". It is a vital extension to everyday language which allows people to manipulate and communicate ideas and relationships that are way beyond the limits imposed by English. A picture speaks a thousand words - very true - but there is no satisfactory verbal description that can deal with even the simple operation of changing the subject of a linear algebraic equation to get a numerical answer to a simple electrical problem. Try describing, concisely, the Fourier transform in simple words.

 

[Crazymechanic]

another thing people are not ready to wait these days, eberyone needs everything on the spot.understanding and knowledge including , but the thing is understanding and " gut" feeling comes only after a while , after many hours spent learning and trying to undersand stuff.
I may hate that myself but sadly it's the truth.

So paraphrasing Jack Nicholson, I want to ask you , Can you handle the truth? :D

 

[ZapperZ]

This thread has degenerated into something completely different and is no longer on the physics. It is now done.

Zz.