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[*] posted on 31-8-2005 at 11:55


Electrolysis is used for hydrogen production, certainly on a lab scale.

"Electrons obey ohms law, no matter where they go, and sometimes they go places where the math gets complex. However, this does not change a thing, unless you put your cell inside a black hole it will still always obey the laws of the universe. "

Bollocks!

Plenty of things have non linear I vs V curves, electrolytic cells are among them. Semiconductors and gas lamps are some of the better known ones.

Google finds about 13500 hits for "non ohmic". Are you going to write to them all and tell them they are wrong?

[Edited on 31-8-2005 by unionised]
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[*] posted on 31-8-2005 at 14:34


How can you be so good at chemistry and say something like that? Electrons obey all the physical laws of the universe whether or not you believe it. Just because you are dealing with complex ( and by this I include non linear) and changing impedances does not change a thing. Electronics is a subject I am well versed in having run a hundred million dollar R&D lab where my function was engineering and reverse engineering various technologies. I find it simply astounding to hear such opinions as if electrons follow some magical route just because chemistry is involved. Go back to the statement I first responded to and read it again. The statement was that somehow batteries made a difference in current versus voltage as compared to a line derived power source. I hope you are planning on taking at least some physical science along with your chemistry in order to have a better idea of what you mean when you say "Bollocks!".

It does not matter whether or not the I versus E curves are nonlinear or not, there is still a mathmatical formula to predict the values of each parameter, and you will find that the laws of science are still being obeyed even if you do not like it!

Let me explain this in simple terms for you. Ohms is opposition to the flow of electrons intrinsically. So in any circuit no matter what the conditions a given voltage will produce a given current with a given impedance to the flow of said current. I=E/R still prevails, you must simply find out what the complex value of R is, and R may be negative but the math still works. Maybe I should write them and tell them they are all wrong since the term "non ohmic" is in itself a misnomer. A bad term. Simply because the opposition to current does not follow a linear curve does not mean there is no opposition to current flow, which again is the definition of the term ohms. Why would you wish to make an argument out of my previous statements? Merely because you did not understand what I was saying? There must be better things you can do with your time.

Looking at a source of power as a generator with a voltage, current potential, and internal resistance, it makes no difference where the power comes from, house current or batteries, conditions outside of the generator in the same circuit will not change, and this was the point of my statements. You are creating a whole new subject to argue about, for some reason I do not see. I mean think about it. You quoted my statement that electrons obey the laws of physics and you come back to this statement with "Bollocks!"! Do me a favor. Print this all out and take it to your physics professor, and write back here what he or she has to say about it.

[Edited on 31-8-2005 by IrC]

[Edited on 1-9-2005 by IrC]
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[*] posted on 31-8-2005 at 16:51


...Non-ohmic refers not so much to the instantaneous V/I = R points on the V vs. I graph but more to the derivative, which is in units of rise/run = volts/amps = ohms (dynamic impedance in this case)...

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IrC
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[*] posted on 31-8-2005 at 17:45


That much is clear, but I for one would be happier if they would change the name from "non-ohmic" to something more correct in description. That's all I'm complaining about. Who coined that term anyway and who do we call to get it changed to something more appropriate? To me "non-ohmic" describes a superconductor, or something like one.

Or in general "ohmic" means anything which obstructs the movement or lowers the kinetic energy of an electron in motion. If a field is applied in the circuit there is an energy loss which results in the need to apply more energy to maintain the uniform motion of charges. So we see that to increase the velocity of the charges and compensate for the kinetic energy lost in collisions, we have to increase the accelerating voltage or field. This is why volts push amps.

[Edited on 1-9-2005 by IrC]
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[*] posted on 1-9-2005 at 11:31


Are we at crossed purposes or what?
This is what I mean by Ohm's law

http://micro.magnet.fsu.edu/electromag/java/ohmslaw/

it's the one Ohm postulated a long time ago. The part that I'm talking about is the bit where it says proportional. That's what Ohm said- that's his law.
Any V/I relation that isn't linear (ie where I is not directly proportional to V) is a deviation from Ohm's law.

You can define a dynamic resistance (or impedance) if you want but the law that the bloke wrote is very simple and electrolytes don't generally obey it.

Another sense in which you are clearly talking through your hat is that you keep on talking about electrons, it may have escaped your notice that the current carriers in solutions are not electrons so your whole argument is based on an irrelevance.
That's not the whole story. The V vs I relation is about current- the rate at which electrons pass through a circuit. |If you only have one electron it either does or does not pass a point. If it does then the current is infinite (finite charge, zero time). If not the current is zero.
Given that current is that poorly defined for a single electron, saying it obeys Ohms law is meaningless.

Before you tell me to study some physics perhaps you should take the time to learn what you are talking about.

"Electronics is a subject I am well versed in having run a hundred million dollar R&D lab where my function was engineering and reverse engineering various technologies."
And the fact that you did that without taking the trouble to learn Ohm's law makes it so much more impressive in one sense, but like empty bragging in another.

BTW, one of my drinking buddies is an electronics lecturer- would you still like me to ask his opinion of your work? I'm sure he would enjoy it.
And to answer your first question about how I can be so good at chemistry- well, I studied it for a while then used it to earn a living for a couple of decades. At least most of the time I was doing chemistry- sometimes, when the section needed some electronics doing, they asked me.

[Edited on 1-9-2005 by unionised]
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[*] posted on 1-9-2005 at 15:12


Quote:
Originally posted by unionised
(finite charge, zero time).


Uh, sorry but current is generally in units of coulombs per second, so the 'time' is NOT zero. So for a single electron the current would be either unbelievably small (1.6 e-19 amps) or zero if it doesn't pass in that second.

Oh, and I agree that 'Ohm's Law' refers to linear resistance. And in real life non-linear V/I relationships are very common.




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[*] posted on 1-9-2005 at 16:00


unionised, this all started as I was trying to get someone to see that a line powered supply can do the same job as a battery supply, and you are turning my kiln thread into a bunch of useless argument about how you can have current flow with no electrons at all moving in the circuit. Why bother even hooking wires to your cell? I guess then only protons, holes, and bacteria are moving in your circuits but I for one could not care less, the point of this thread was my kiln. I don't need your insults to my knowledge, intelligence, abilities or past work I have done. Should I post here what I think you and your drinking buddy can go do with your opinions of me?

I think you should go start your own thread and talk about how wonderful you are there, and leave my kiln subject alone. I have better things to do with my time.


[Edited on 2-9-2005 by IrC]
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[*] posted on 1-9-2005 at 21:56


Twospoons, if the charge takes half a second, the current is twice as large, if it takes .1 sec the current is 10 times as large
Since the time taken for an electron to pass a mathematical point (ie with no size) is zero, the current is infinite.

IrC,
So, when do you admit that you totally failed to understand Ohm's law then? Is that when you apologise to Darkfire for not understanding the impedance matching idea? When do you explain to me how you were so conceited that, rather than check on the accuracy of those 13500 folks, you decided you were right and patronised me?
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[*] posted on 2-9-2005 at 02:43


Hello unionised,

I don't think that's quite correct; since an electron has finite size, finite charge, and finite velocity, the current resulting from its passage cannot be infinite.

Regards,
Joe

Quote:
Originally posted by unionised
Twospoons, if the charge takes half a second, the current is twice as large, if it takes .1 sec the current is 10 times as large
Since the time taken for an electron to pass a mathematical point (ie with no size) is zero, the current is infinite.
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[*] posted on 2-9-2005 at 06:49


Well, all these arguments aren't really that neccesary, what I had meant all along was that to power the cell, its more efficient to have very low voltages and increase current as much as possible. Yes, agreed that when you pump electrons(amps), you need energy(volts). But current is limited by resistance and voltage. What you mean when you say that by to increase current, you need more voltage. That is true, when you have fixed resistance. Then, to pump more amps, you need more volts.

What I mean is that you do not neccesarily need more volts to pump more amps. Because ultimately, batteries and AC power supply are determined more accurately by power. P=VI. That is, for the same power, you can have more volts but less amps. Conversely, you can more amps, but less volts. For the batteries, this means that if you draw a larger current by lowering resistance, you draw more power and the batteries goes flat rapidly; not at all what we want for we want a sustained production of hydrogen gas, we certainly do not want the battery to go flat in 10 mins.

Instead, we can use the wall adapter, the wall adapter steps down voltage, but steps up current. The power station provides a certain amount of power. Its up to you to use allocate the power to push only a few electrons with a lot of energy, or push a lot of electrons, but all them having lower energy. That is how you can lower the voltage as much as possible, but still increase current.

What unionised means is not that Ohm's Law is not obeyed. There's a relationship between resistance, ohms and volts, yes, no one's denying that. But Ohm's states that the relationship is linear, that is, the graph of the current vs volts is a line. But from normal experience, we know that it is not neccesarily a line. So this sort of conductors is termed non-ohmic. Which means that they do not conform to the linear rule. Non-ohmic does not mean that the conductors do not obey the part of volt push amps.




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[*] posted on 2-9-2005 at 07:38


Quote:
Originally posted by unionised
Since the time taken for an electron to pass a mathematical point (ie with no size) is zero, the current is infinite.


What the? Oh, I see, you slept the week when the prof was going over current flow. Something about a variable, vector even, named J.

Current is electrons <B>passing through a cross section.</B> At t=0, they were on one side, at t=1 they passed it. No infinities.

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[*] posted on 2-9-2005 at 11:54


You need merely think of a generator and compare the internal impedance of one to another. More current capacity does not dictate that more amps will flow, it depends upon the circuit. I didn't bother to get into mobilities, and the fact that the electrons in a cell have the highest mobility. In fact, I give up on this entire line.

Can we go back to talking about kilns and improvements in same?
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[*] posted on 2-9-2005 at 18:47


Try this IrC:

if you plan on making high temp stuff, this is ok (wouldn't buy the refractory blanket or castable, but the brick is good)

http://www.uu77.com/groupslist.aspx?CategoryID=109&Categ...
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[*] posted on 3-9-2005 at 02:33


I will just deal with the current current debate here.
It takes just the same time to pass through a cross section as it does to go past a point.
"Current is electrons passing through a cross section. At t=0, they were on one side, at t=1 they passed it. No infinities.
"
In what units are you measuring T? t=1 day, 1 hour, 1 nanosecond?

The point I was making is that at t=0 the electron is on one side; at T=delta t it is on the other side. As delta t tends to zero the rate of change of charge dQ/dt tends to infinity.
The instant the electron clears the starting gate the charge goes from nil to about 10^-16C. That happens in zero time, at one instant it's on one side, the next instant, its on the other. The time interval is vanishingly small so the current dQ/dt is infinite.
The average current over any practical time scale is small, but the instantaneuos cuurent is infinite*. There's a matematical function to describe this called something like "Kroneker's Delta" an infinitely narrow, infinitely high spike with unit area.

Anyway, the fact that we are having this debate proves my point.
Ohms law talks about currents and currents, as we have seen, are poorly defined for single electrons so IrC's assertione that every (single) electron obeys Ohm's law is clearly not true.
Any further discussion about current with single electrons will just reinforce this point.

IIRC Ohm was dead roughly 50 years before the electron was characterised- He was a clever man, but not that clever, he didn't include electrons in his law.

I will set up another thread to avoid cluttering this one further while setting the record straight.
Here it is.
http://www.sciencemadness.org/talk/viewthread.php?tid=4405&a...


* actually, since attosecond timings are possible and picoseconds are quite commonplace, this is not strictly true one electron per picosecond is a perfectly respectable current. Since the debate was about single electrons it's not an important matter


[Edited on 3-9-2005 by unionised]
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[*] posted on 3-9-2005 at 05:16


The time it takes an electron to traverse a geometrical point in space is simply the electron's "length" (diameter) divided by its velocity, no? Since both of these quantities are finite, the current is also finite.

Using the "classical" electron radius of about 2.82 x 10^-15 meters, a velocity of 0.1 c (ignoring relativistic length contraction) and a charge of 1.6 x 10^-19 coulomb (your value of 10^-16 is incorrect), I get a very finite current of about 851 amps.

Quote:
The point I was making is that at t=0 the electron is on one side; at T=delta t it is on the other side. As delta t tends to zero the rate of change of charge dQ/dt tends to infinity.
The instant the electron clears the starting gate the charge goes from nil to about 10^-16C. That happens in zero time, at one instant it's on one side, the next instant, its on the other. The time interval is vanishingly small so the current dQ/dt is infinite.
The average current over any practical time scale is small, but the instantaneuos cuurent is infinite*. There's a matematical function to describe this called something like "Kroneker's Delta" an infinitely narrow, infinitely high spike with unit area.
...[Edited on 3-9-2005 by unionised]
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[*] posted on 3-9-2005 at 08:20


Quote:
Originally posted by unionised
"Current is electrons passing through a cross section. At t=0, they were on one side, at t=1 they passed it. No infinities.
"
In what units are you measuring T? t=1 day, 1 hour, 1 nanosecond?


...WTF...?! How fucking desperate ARE you?

<B>You know as well as I do that time doesn't matter, it's all factored when going back to coulombs <I>per second</I>!</B>

Going to dt --> 0 doesn't work for the express reason that nothing happens in zero time. I guess you forgot that before you made an ass of yourself... (where's that rolleyes smiley)

And besides, quantum theory applies at this scale (obviously). Ohm's law works quite nicely for averages of many electrons. Ohm's law still works, but you keep trying to undermine it with dubious statements designed not to argue scientific fact but to publicly masturbate your ego. Which reminds me, since this post is getting somewhat heated and you will certainly reply to it, in an attempt to draw me into the fray, this will probably be my last word on the subject.

Quote:
Using the "classical" electron radius of about 2.82 x 10^-15 meters, a velocity of 0.1 c (ignoring relativistic length contraction) and a charge of 1.6 x 10^-19 coulomb (your value of 10^-16 is incorrect), I get a very finite current of about 851 amps.


There you go, a finite answer using your imagined situation <U>properly</U>. You were saying?

Tim




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[*] posted on 3-9-2005 at 08:34


I'm not desperate yet, and I don't think I will be any time soon.
The point I was making is that one second is a totally arbitrary time and that the interval, delta t, that you need to divide the change in charge (deltaq) by to get the current isn't 1
It isn't 1 second, it isn't 1 day. It's the time taken for an electron to cross the line.
If the electron were a block of wood with the size and velocity you give it then the time interval would be as you calculated and the current would be the value you gave it.
The problem is that we are talking about electrons.

The size of an electron is poorly defined but the value you have use is perfectly reasonable, the trouble is that it's classical.
You seem to have forgotten that while you made your "propper" finite calculation. Who exactly has made a fool of themself?
However, I take the view that, since the elecrons wave function is infinite in extent you cannot use it's size in this way because, if you do, then it takes an infinite time for an electron to cross from one side to the other- an equally absurd notion.

The best way forward that I can see for expressing the position of an electron is to use the maximum of its wave function.

That, of course, is a mathematical point and takes no time to cross the line.

You can take any value you chose as the size of an eletron in this context. A mathematical point or an infinite wave function. You seem to have chosen a value in between those two extremes and calculated from it as if there is some God -given reason to say it's correct.
With an ego like that I'm sure that you can masturbate it wherever you want.

All of this goes to prove my point that, since Ohm's law refers to current and current isn't well defined for a single electron, IrC's assertion that Ohm's law holds for every electron is questionable at best.



BTW, Perhaps it would be better to move this discussion to the other thread I set up.



[Edited on 3-9-2005 by unionised]

[Edited on 3-9-2005 by unionised]
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