Sciencemadness Discussion Board - !the tread IrC asked me to start.

!the tread IrC asked me to start.

unionised - 3-9-2005 at 03:54

Once long ago, there was a board brought forth for the discussion of science, it served to inform the world of the ideas and experiences people had and gave them a chance to ask questions.
It came to pass that a man who, notwithstanding his expertise in the field, had a problem- his kiln wasn't hot enough. IrC, for it was he, sought help by starting a thread, and it was this one

http://www.sciencemadness.org/talk/viewthread.php?tid=4376&a...

Much discussion was made of heating elements and refractories. Some others sugested the use of other means of heating, of arcs and exotic fuels. One talked of using the O2/H2 flame which is admirably hot, and can be fueled from an electrolytic cell. This was all very well until the one named darkflame89 said of the efficiency of these cells

"Yes, the volts push amps matters if u are using batteries. "
Now, sadly, it was not totally clear to what he referred. He was, I think, trying to establish the fact that, the voltages from the mains are vastly higher than the emf of the H2 generating cell. but that, with the voltages available from batteries, the cell emf is significant.
IrC, (he who would build a hotter kiln) was unimpressed by this posting and he replied.

"I=E/R, no matter where you get the electricity. When it comes to AC power you are still dealing with ohms law, you are just dealing with a cycling voltage where terms such as peak, average, and root mean square come into play. "
Unionised, feeling that darkflame89 had been wronged by this and that, furthermore, against the designs and purposes of the board, that IrC had posted something that was untrue, replied thus
"IrC
When did electrolytic cells, like those used for hydrogen generation, start obeying Ohm's law? "

And IRC's replied thus.
"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.

It is not magic, just science!"

Unionised, once again fearing for the inegrity of the board, should its accuracy be tarnished, explained to IrC that he was mistaken saying

"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? "
It seems that IrC was angered by this which he perceived as an atack on his reputation, for he replied

"Electronics is a subject I am well versed in having run a hundred million dollar R&D lab "
So blinded by his anger was he that, he failed to realise that the person he addressed had left University some long time since and he wrote
"I hope you are planning on taking at least some physical science along with your chemistry
Print this all out and take it to your physics professor, and write back here what he or she has to say about it."
Convinced of his own correctness, rather than testing his own beliefs, he replied to the posting saying

"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.
Maybe I should write them and tell them they are all wrong since the term "non ohmic" is in itself a misnomer. "
Verily did he thereby cast doubt on the knowledge of the thirteen thousand, where the lack of knowledge was his own.
And he did pour scorn on the word of Ohm, saying
"It does not matter whether or not the I versus E curves are nonlinear or not,"

And unionised, puzzled by this reply, sort first to clarify matters stating
"This is what I mean by Ohm's law "
and citing a learned reference that pointed to the Law of Ohm.
For it is written " The current flow is directly proportional to the applied potential diiference".
Yea, poor and imperfect is our world, for in truth this law is not always followed. It is hard to find a single thing that gives light or motion where the law is obeyed. Wickedly do the gas discharge tubes fail in their obedience, so too with the semiconductors.
Further, by IrC's words was Unionised left uncertain, and he stated that
"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".

And, to explain that, as a man of many summers, he no longer studied under a master, by title of professor, or any other; Unionised answered IrC's question thus
"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. "
and therby he sought to establish that he was not unversed in the field of physics.
Once more was the ire of IrC roused for he did reply

"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"
Where he made a false accusation about Unionised, for it was IrC who had first brought the law of Ohm into the thread and the discussion of the electrons. And Unionised had only sought to establish that these made no difference for electrons do not travel unchaperoned through solutions, and it is through solutions that charge must pass to generate hydrogen. Though these electrons must travel unto and leave the solution, yet they travel through it bound unto other matter.
And also did IrC say
"Should I post here what I think you and your drinking buddy can go do with your opinions of me? "
And Unionised wondered, rather than the thoughts of my fellow drinkers with whom you have no dealings, it is not better to consider the opinion of others on the board.
And IrC also said

"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."
Which again puzzled Unionised for he had not sought to glorify himself, even though he had ventured that he was better versed in the art of electronics than his coleagues, for his colleagues too are chemists and have spent their learning time on other matters.
But yet it was IrC who vaingoriously said
"Electronics is a subject I am well versed in having run a hundred million dollar R&D lab "

So be it.
And now I ask those who would comment on such matters to do so here in order that the thread on kilns maintains such purity as it may.

[Edited on 3-9-2005 by unionised]

vulture - 3-9-2005 at 05:06

Quote:

Electrons obey ohms law, no matter where they go, and sometimes they go places where the math gets complex.

I'm not a pro at electronics, but this statement would indicate conduction through superconductors is not done by electrons...

unionised - 3-9-2005 at 05:38

Your'e right true, it does imply that, but that's the least of his problems. Ohm's law is like the ideal gas laws, nothing obeys it fully.

zoomer - 3-9-2005 at 06:31

Oh contraire, good sir unionized!

Everything follows Ohm's Law exactly. Ohm's Law (V = I / R) is a specific application of Newton's Second Law (F=ma), another universal constant. Adherence to the law does not change with the material in the examples you have given. What changes is the materials' resistance to the directional movement of electrons. Most materials, like copper wire or the graphite-clay mixture in simple circuit resistors, have linear conduction curves, because they maintain constant R over a wide range of applied force (EMF). Semiconductors circuits and electro-cells, on the other hand, undergo very complex, nonlinear molecular changes to applied EMF, and therefore R is constantly changing. But the current always remains exactly proportional to the applied force with respect to the instantaneous resistance to that current.

Superconductors do conduct by electrons. When a material becomes superconducting, R goes to practically zero, and electrons spontaneously begin unconstrained movement. With R=0, only the tiniest of force is needed to direct these wandering electrons in a certain direction, and in fact often spontaneously begin a unidirectional flow through the superconductor.

[Edited on 3-9-2005 by zoomer]

[Edited on 3-9-2005 by zoomer]

[Edited on 3-9-2005 by zoomer]

IrC - 3-9-2005 at 06:41

Don't bother trying to explain cooper pairs to unionized, his head is so big already it would explode.

If ohm is defined as obstruction to the flow of an electron then what I said was true. Two electrons joined in a quantum state do hot have to act the same as a single electron.

[Edited on 3-9-2005 by IrC]

unionised - 3-9-2005 at 07:21

Ho Hum
Ohms law states that the current is proportional to the voltage.

Anyone think it states anything different?

That's a very simple law to understand. From his point of view it was based on empirical observation. Within the limits of his experiments, the current was proportional to the voltage- a nice linear relation.

It's very odd to say that "Most materials, like copper wire or the graphite-clay mixture in simple circuit resistors, have linear resistance curves"
It isn't true for most things because it doesn't work for gases or "insulators".
For most things (rather than the rather small subset you have chosen) it's not true.
On the other hand it's fairly close for metalic conductors, provided that they are thick enough not to heat up much.

Since it isn't true, it doesn't follow from Newtons laws.

Please don't bother trying to explain Cooper pairs to me because I already know about them. On the other hand, if Zoomer thinks the electrons in a superconductor are "unconstrained", perhaps someone should explain them to him.

"If ohm is defined as obstruction to the flow of an electron then what I said was true"
Ohm is a unit or a long-dead bloke. Neither of them is defined in the way you sugest.

If "banana" is defined as a swarm of left-handed bees......
It doesn't make sense to make comments like that; you aren't permited to change the definitions of words just to suit your own argument.

Ohmic is the term used for those (relatively few) materials or items that obey Ohm's law quite well.

Whether or not I'm big headed isn't the point. IrC's wrong headed.

Not only that but for him to brag like this
"Electronics is a subject I am well versed in having run a hundred million dollar R&D lab " leaves him ill-placed to comment on my ego, particularly when he's just plain wrong. I'm also not sure how he can dismiss the 13500 folks out there who disagree with him and not be counted as big headed himself.

What exactly have I said about this that indicates that I'm big headed?

12AX7 - 3-9-2005 at 08:10

Quote:

Originally posted by unionised
It's very odd to say that "Most materials, like copper wire or the graphite-clay mixture in simple circuit resistors, have linear resistance curves"
It isn't true for most things because it doesn't work for gases or "insulators".
For most things (rather than the rather small subset you have chosen) it's not true.

'Course, insulators have a defined resistance too. It drops at the breakdown voltage, sure, but any material changes under extreme conditions. Silver and copper will burn like a fuse and go open (until much larger voltages!), semiconductors fail open or shorted, heck even air and vacuum change. Don't forget that superconductors have a critical field strength that can be easily broken, given the narrow skin effect conduction mode.

Quote:

Whether or not I'm big headed isn't the point. IrC's wrong headed.

Quote:

What exactly have I said about this that indicates that I'm big headed?

OMG, ROTFLMAO. Well let me see, who opened this new thread? Who picked the fight? Who continues it?

Hmm...

Ya know unionized, it's getting real sticky around here.. quit the mental masturbation.

Tim

[Edited on 9-3-2005 by 12AX7]

zoomer - 3-9-2005 at 10:13

Well, that's how electricity worked when I was designing integrated circuits for a major chip manufacturer. But that was a long time ago, so things probably have changed since then...

unionised - 3-9-2005 at 10:33

Zoomer,
Were you using superconductors or did these chips have linear voltage vs current curves or what?

Tim,
who opened this new thread?
The man who was asked to.

"Who picked the fight?"
The man who disrespectfully commented on Darkflame's post without bothering to understand it and, while he was about it said something simply wrong.

"Who continues it? "
By that question and the others, you do, I'm just posting a reply.

I can't help wondering why you keep going on about masturbation. Have you got the wrong bit of the 'net?

I can't see what's the big problem about pointing out that some bloke wrote a law and it isn't followed.
The rule is that I is proportional to V. For elecrolytic cells, among other things, it isn't true so citing it in reply to a point about such cells isn't logical. It's like using the ideal gas laws to calculate water flows.

Eclectic - 3-9-2005 at 13:33

http://www.grc.nasa.gov/WWW/K-12/Sample_Projects/Ohms_Law/oh...

Magpie - 3-9-2005 at 14:45

I went to my university physics text and read the scant history on Ohm's Law (Modern University Physics, Sears, Zemansky et al, 1960). German scientist Georg Simon Ohm (1789-1854) noticed that there was a proportionality constant between current and voltage for certain metallic conductors. I interpret this to mean he found a linear relation over some specific range or set of conditions. The book also shows the non-linear relationships for vacuum tubes and electrolytes. I don't think Mr Ohm would have considered these latter cases to be examples of his law.

On the other had Ohm's Law does give the resistance of a material for any given set of current and voltage. So it has a practical use even in non-linear situations.

I conclude that you both have a point, but the application must be carefully defined for the non-linear situation.

trilobite - 3-9-2005 at 15:09

Is there a problem with the Ohm's law? Even if resistance is defined as R=U/I, it can still be that for a certain material the resistance isn't constant over the whole voltage range, which makes it nonlinear. However, for a perfect resistor the resistance should stay constant no matter what.

There wouldn't be much sense in the electrolytic analysis technique of polarography it if wasn't for nonlinearity.

[Edited on 3-9-2005 by trilobite]

unionised - 3-9-2005 at 23:52

Magpie, thanks for taking the time to post that, it's good to know that someone else is prepared to look at what Ohm actually said.
Trilobite It's not a matter of a "problem" with Ohm's law but, like the gas laws, you need to know where you can apply it.
For resistors it's fine for some things (like electrolytes as you say) it simply doesn't apply.
What you can't say is "Electrons obey ohms law, no matter where they go", which is what IrC said.

Ohms's law states that the current is directly proportional to the voltage.
That can be written as
I (symbol for proportionality) V
or as
I =KV
Where K is a constant of proportionality.
If V and I don't behave in such a way that you can write this expression then Ohm's law isn't obeyed. K (known as the conductance) is constant- because the law says so. So does its reciprocal (the resistance).

For any object there will be a relation between the applied voltage and the current.
V=f(I) but if that function isn't linear (or if f(0) isn't 0 )we are talking about something non ohmic.

I see it's gone quiet on the meaning of current for a single electron.

vulture - 4-9-2005 at 04:32

Quote:

Two electrons joined in a quantum state do hot have to act the same as a single electron.

Yes and which conclusion do you draw from that? It still are electrons, so they defy ohms law? Or because it's a quantum state and thus they don't have to obey ohms law?
But then again, electrons are always in one quantum state or another.

To me, you are just proving unioniseds point, that is, ohms law should only be used where it applies. And Newtons law isn't absolute either...

I also find it very strange that you are suddenly a fundamentalist defender of scientific theories, claiming they explain everything, while on the other hand you take the creationists approach in an other thread. Rather contradictory.

[Edited on 4-9-2005 by vulture]

IrC - 4-9-2005 at 08:06

Vulture you really do flip from extremes don't you. If you were able to see anything else maybe you would figure out that there are those who are not creationists or fundamentalist. And if you knew anything about superconductors then you would know the most accepted theory for superconductivity in metals use cooper pairs. Since two electrons joined in a cooper pair see no resistance (hence the term superconductor) they therefore do no see the resistance a single electron would in the same piece of metal. Let me guess, you also take the view that anyone who posts a different view is also being disrespectful. Too bad you claim this board is about science when really it is merely a forum for you to voice only that which you agree with.

vulture - 4-9-2005 at 11:09

Quote:

And if you knew anything about superconductors then you would know the most accepted theory for superconductivity in metals use cooper pairs.

Yes, this is true, where did I deny that?

Quote:

Since two electrons joined in a cooper pair see no resistance (hence the term superconductor) they therefore do no see the resistance a single electron would in the same piece of metal.

Yes, again, I accept this theory. Where did I say I didn't?

Quote:

Let me guess, you also take the view that anyone who posts a different view is also being disrespectful.

Again, where do I say this?

Quote:

Too bad you claim this board is about science when really it is merely a forum for you to voice only that which you agree with.

This is a ridiculous and untrue accusation. If that would be the case I would just censor the posts of those who disagree.

Instead, I try to use reasonable arguments to backup my point, unlike you, who immediatly snaps into personal accusations.

READ what people post. READ it. Then form an opinion and THEN judge.

Furthermore, again you are not answering the questions I raise in my post, just as in all the other discussion I've had with you.

I also think that your behaviour towards other members is crossing the line of what is decent. I will not refrain from sanctions because that would allow you to say I'm biased, so be warned.

You are using every warp and stall tactic possible in this thread to avoid having to answer the questions raised.

So, let me ask again. Are you saying because cooper pairs can't be seen as normal electrons it is ok they defy ohms law?

This is just a QUESTION. ANSWER it. Then start throwing mud all you like, I don't fucking care. If you get too much of a nuisance, we'll deal with it.

Perhaps you should consider a career in politics, as you already master the most important skill necessary: dodging nasty questions.

[Edited on 4-9-2005 by vulture]

unionised - 4-9-2005 at 11:26

I'm not sure what IrC has been creationist about but to be fair, there isn't a strict contradiction between taking a creationist view of things like evolutionary psychology and a strictly logical "hard core scientist" view on the laws of physics- after all, they might be God's laws.
On the other hand, it makes sense to ensure that the laws you chose to defend are correct- you might not get far with the ideal gas laws. Whatever point of view you take, you should be able to defend the point logically and answer such questions as people ask.

Questions like, if IrC says
"Too bad ... it is merely a forum for you to voice only that which you agree with."
Does he expect you to voice opinions that you don't agree with?
To me, that seems odd.

Incidentally, if there were only 1 electron there, it wouldn't be the same piece of metal, the nuclei would be in different places, this lattice distortion is what keeps the pairs paired (see, you really don't need to tell me about it).

BTW, Vulture, I know you're a mod but you seem to be jumping the queue. I think IrC should answer my question first because I asked first.
"IrC
When did electrolytic cells, like those used for hydrogen generation, start obeying Ohm's law? "

On the other hand, I'd be quite happy to see him answer either question.

[Edited on 4-9-2005 by unionised]

Please play nicely...

I am a fish - 4-9-2005 at 12:36

Ohm's Law can be considered in two ways:

The statement that the current through an object is proportional to the potential difference across it: Whilst this holds true in some situations, in others it is manifestly false. Therefore, by this definition, Ohm's law is an approximation, which only holds true in some circumstances.
The statement that resistance is the ratio between potential difference and current: In this case, Ohm's law is always correct (as it is always possible to find a value of resistance to match given values of current and voltage). However, in non-linear systems, the resistance will be a function of voltage. In systems with hysteresis, the resistance will also depend on the past history of the voltage. In microscopic systems, there will also be random fluctuations due to the discrete nature of the current. Therefore, Ohm's Law is always correct, but only as a mathematical construction, and not as a reflection of physical reality.

IrC - 4-9-2005 at 17:06

"So, let me ask again. Are you saying because cooper pairs can't be seen as normal electrons it is ok they defy ohms law? This is just a QUESTION. ANSWER it. Then start throwing mud all you like, I don't fucking care. If you get too much of a nuisance, we'll deal with it."

Earlier in this stupid argument I had posted the comment that superconductors were non ohmic. This means non ohms law. Supersonducting electrons see no resistance so there is no obstruction to their flow. To obey ohms law would create infinities. Voltage divided by zero would give infinite current.

Quote:

The statement that resistance is the ratio between potential difference and current: In this case, Ohm's law is always correct (as it is always possible to find a
value of resistance to match given values of current and voltage). However, in non-linear systems, the resistance will be a function of voltage. In systems with hysteresis, the resistance will also depend on the past history of the voltage. In microscopic systems, there will also be random fluctuations due to the discrete nature of the current. Therefore, Ohm's Law is always correct, but only as a mathematical construction, and not as a reflection of physical reality.

This is exactly the point I have been making from the other thread to this one. This entire thread is a mere creation by unionized to attack me and good old vulture is joining in like a pack of rabid jackals. Veiled threats of baning me and all. And all this because unionized said I was being disrespectful to darkflame for not agreeing with them. 99.9 percent of all bashing has been by unionized towards me yet I am the one vulture threatens to ban? Because I choose to state my own opinions?

I suggest you all go back and read my words from the first thread to this one, and see where it was these attacks against me are justified.

[Edited on 5-9-2005 by IrC]

Edited to fix quotation.

[Edited on 5-9-2005 by I am a fish]

Lambda - 4-9-2005 at 19:16

I personally find it rather sad, that these discussions are gaining ground on a personal level. The Whimsy thread is more appropriate for personal views, and/or attacks if desired. We all share the same passion and interest for science, and I would hate to see anyone banned because of personal disputes and/or issues with each other. We all have the intellect to do things differently, from those who we would refer to as stupid or foolish. I would like to see intellect prevail here, and mud left alone for what it is. This discussion is ok on a scientific level, and we should continue to keep it in a field that brought us all together in the first place. Common interest, is what motivated me to join this wonderful forum, and we should keep it wonderful, inspiring and motivating, don't you think ?.

darkflame89 - 4-9-2005 at 19:27

Ok, my previous statement was very vague and unclear. There's no need to start a huge thread to argue on the validity of this statement. Both views presented are correct depending on how you want to argue about it.

Ohm's law, strictly speaking, is the relationship between ohms, volts, and amps. He says that this relationship is linear. Well, his statement is somewhat true and untrue. Untrue because conductors do not follow this linearity strictly. For example, if you plot the I-V graph for say copper(II) sulphate solution, you don't see a straight line. The graph for the filament lamp looks like a y=x^3 curve. That's not saying that Ohm's Law is not obeyed. Its like water flowing in the pipe. The 'oomph' factor of the water is volts. The volume of water flowing is amps and resistance is obstacles along the way. Now, let's say I want a relationship between the oomph factor, volume of water flowing past a point per unit time, and the no. of obstacles in the pipe. Presume Darkflame's Law stated the no. of obstacles in the pipe is directly proportional to the oomph factor and inversely proportional to the volume of water flowing in the pipe. Of course, what I am implying is the graph of oomph factor vs volume of water passing through a point per unit time is a line.
Someone measures this and plots the graph, and behold! He finds out that the relationship is not linear but rather curve. Does this mean that there's no relationship between the 3 factors. No, it just mean that the relationship is not linear and nothing else! Its like Einstein found out Newton Gravitational Theory is wrong. Does it mean that we change to Relativity and stop using Newton's Law? No, because Newton's Law is not completely wrong, its just that the relationship between the mass and gravity is not completly correct!

Now, back to the part about IrC's statement about "The comment about lowering voltage and raising current will not work as it is volts that push amps. " is not true, because we are thinking about different stuff completely. Lets deal with your statement

Quote:

This means for a given conductivity the only way to increase current is to raise the voltage, and the resistance in an electrolytic cell will be considerable compared a metal such as copper. Therefore it would mean raising to an even higher voltage to increase the current flow as compared to the current in a wire.

Well, your statement works when we are talking about batteries. What you are referring to is, for a fixed resistance, if you want to raise current, you have to raise voltage. True, looking at I=V/R, we can see that if R is constant, then to increase I, we have to increase V. Another way to raise current is to keep voltage constant and decrease R. But this is not very feasible. The third way to increase I, i to connect a few batteries in PARALLEL. Then amount of I increases too, without increasing voltage.

Now, what I was thinking about was AC current, not batteries. I am talking about transformers here. Now the electricity supplied by the generators in high voltage, high current. The eaxt value of V and I doesn't matter because ultimately Power supplied by the generator is the same, and P=IV. Using a transformer to step down voltage for safe usage will step up current because looking at P=IV, for the same amt. of P, decreasing V means increasing I.

Therefore, it is possible to decrease voltage as much as possible(to 1.5 V) and increase current as much as possble.
Hope I have made myself clearer and will all of us please stop this argument over who is correct.

PS. Quantum theory does not come into picture here at all. Because the BCS theory only applies when the particles are close to not vibrating(aka absolute temps). In fact, they are looking for better explanations to explain high temperature super conductivity.

unionised - 4-9-2005 at 21:58

Can we get something straight,
Ohm's law is what he said it was, that's the first of I am a fish's definitions.
He wouldn't have been remembered for saying "you can measure 2 things and calculate a ratio". He didn't say it, it isn't his law.
You can divide the current by your shoe-size if you want, it doesn't matter, it's not Ohms law.

How many of you were taught at school that V=IR is Ohm's law?
It's only true if R is a constant.

I am a fish - 4-9-2005 at 23:09

Quote:

Originally posted by unionised
Can we get something straight,
Ohm's law is what he said it was, that's the first of I am a fish's definitions.
He wouldn't have been remembered for saying "you can measure 2 things and calculate a ratio". He didn't say it, it isn't his law.
You can divide the current by your shoe-size if you want, it doesn't matter, it's not Ohms law.

How many of you were taught at school that V=IR is Ohm's law?
It's only true if R is a constant.

If we want to consider what Ohm actually said, then his law is:

(Current Density) = (Conductivity) x (Electric Field Strength)

V = IR is actually the macroscopic version of his law.

Quote:

Originally posted by IrC
Earlier in this stupid argument I had posted the comment that superconductors were non ohmic. This means non ohms law. Supersonducting electrons see no resistance so there is no obstruction to their flow. To obey ohms law would create infinities. Voltage divided by zero would give infinite current.

The voltage across a superconductor will always be zero, and so there will be no problems with infinite current. Furthermore, a superconductor will only permit a finite current, as if it exceeds a certain value, the magnetic field generated will exceed the critical flux density, and the material will stop superconducting.

darkflame89 - 4-9-2005 at 23:51

Ah.......all this argument for nothing..I ran a search for "Ohm's Law" on google and clicked on the first link I could find. Google gives a whole range of definitions gathered from all over the Web.
We can argue our ground based on these:

Definitions of Ohm's law on the Web:

V = IR, where V is the potential across a circuit element, I is the current through it, and R is its resistance. This is not a generally applicable definition of resistance. It is only applicable to ohmic resistors, those whose resistance R is constant over the range of interest and V obeys a strictly linear relation to I.
www.lhup.edu/~dsimanek/glossary.htm

States that, in a given electrical circuit, the amount at current in amps is equal to the pressure in volts divided by the resistance in ohms. The formula is:
www.needhamre-roofing.com/Glossary.htm

The voltage across an element of a dc circuit is equal to the current in amperes through the element, multiplied by the resistance of the element in ohms. Expressed mathematically as E=IxR. The other two equations obtained by transposition are I=E/R and R=E/I.
www.esdsystems.com/training/glossary.asp

Electronics: The mathematical relationship between electrical current (I), resistance (R) and voltage (E); named for Georg Simon Ohm. Ohm's Law states that current in a resistance varies in direct proportion to voltage applied and inversely proportional to resistance and can be phrased three ways: E = IR The voltage is equal to the current multiplied by the resistance. I = E/R The current is equal to the voltage divided by the resistance. R = E/I The resistance is equal to the voltage divided by the current.
support.radioshack.com/support_tutorials/glossary/glossary-o.htm

Voltage equals resistance multiplied by current.
www.partnertechnologies.net/support/glossary/o.htm

The law which relates current measured as Amps (I), voltage (E) and resistance measured as Ohms (R). The law is E = Ix R. It can also be expressed as I = E/R, or R = E/I.
www.e-ratecentral.com/resources/help/glossary/o.asp

Written as I=V/R where I is the current flowing, V is the voltage and R is the resistance.
www.electroflash.org.nz/schoolh/glosspr.htm

The relationship that exists between the electrical parameters of voltage (electrical pressure), resistance (the opposition to the voltage), and current (the flow of electrons in the circuit). Ohm's Law states that the amount of current flowing in a circuit is equal to the applied voltage divided by the circuit resistance.
www.nuhorizons.com/Glossary/BasicElecConcepts.html

E = IR, where E is the potential in volts produced by the flow of current (I) in amperes through a length of material exhibiting resistance (R) in ohms.
www.spwla.org/library_info/glossary/reference/glosso/glosso....

The basic math needed for nearly all electrical calculations. Please see a dictionary or Pocket Ref for all of the variations on Ohm's Law! E=I*R (voltage(E)=amperage(I)*resistance(R)), and all of the algebraic variations of this (I=E/R, R=E/I). Also, for DC circuits, Watts=Volts*Amps. For AC circuits, Watts=Amps * Volts * Cosine of phase angle theta.
www.otherpower.com/glossary.html

Ohm's law is a mathematical formula that is used to describe the relationship between voltage (V), current (I), and resistance (R). Ohm's law can be written as follows:
ehs.sc.edu/modules/Electrical/02_Definitions.htm

E=IR, or I=E/R, or R=E/I. E=voltage, I=current, and R=resistance.
members.tripod.com/~masterslic/advise.html

(Ohm's law) ([omacr]mz) [George Simon Ohm, German physicist, 1787–1854] see under law.
www.merckmedicus.com/pp/us/hcp/thcp_dorlands_content.jsp

Named after the German physicist Georg Ohm who in 1827 described resistance to electrical flow. Expresses the fundamental relationship between voltage, current, and resistance. Current (Amps, or I ) in a circuit equals Voltage ( E ) divided by Resistance ( Ohms, or R) I = E / R or Amps = Volts / Ohms By using simple algebra Ohm's law can be rearranged as: E = IxR or Volts = Amps x Resistance And also be rearranged a third way: R = E / I or Resistance = Volts / Amps- So to recap: The current flow in a circuit depends on both the voltage of the source ( battery, or PV ) and the
www.independent-power.com/electrical_terms.htm

the empirical relationship between the current, potential difference, and resistance in an electrical circuit: V = IR.
phobos.ramapo.edu/~bmakofsk/energysociety/glossary.htm

Electromotive force across a circuit is equal to the current flowing through the circuit multiplied by the total impedance of the circuit. (Basic Science/Electricity/ohmslaw.htm) (Course Material/EddyCurrents/Physics/currentflow.htm) (Course Material/EddyCurrents/Physics/impedance.htm)
www.ndt-ed.org/GeneralResources/Glossary/letter/o.htm

The current flowing through a circuit is directly proportional to the electromotive force (emf) across the circuit. Expressed as: E=IR in which E is the emf (voltage), I is the current (amperes), and R is the electrical resistance (ohms). This is an analog of the relation defining airway resistance, Raw: (pressure difference along the airways) = (flow through the airways) x Raw.
www.ventworld.com/resources/glossary.asp

Formulas that quantify the relationship between Voltage, Amperage and Ohms
www.grote.com/tech/dictionary/

the fundamental relationship between voltage, current, and resistance. It is usually stated as: E = I*R, or V=I*R, where E or V = voltage (in volts. E stands for "electromotive force" which is the same thing as voltage), and I = current (in amps), and R = resistance (in ohms). The equation can be manipulated to find any one of the three if the other two are known. For instance, if you know the voltage across a resistor, and the current through it, you can calculate the resistance by rearranging the equation to solve for R as follows: R = E/I
www.aikenamps.com/AmpTerms.html

The statement of relationship between current, voltage, and resistance. Where I = Current, E = Voltage, and R = Resistance, I=E/R, E=IR, and R=E/I. The equation for calculating resistance in series is R 1 + R 2 + ... + R n = R total . The equation for calculating resistance in parallel (eg for speakers and subwoofers) is 1/R 1 + 1/R 2 + ... + 1/R n = 1/R total
www.sfxaudio.com/AudioSchool/glossary.asp

The law that explains the relationship of voltage, current, and resistance in electrical circuits. For example: V = IxR; I = V / R; R = V / I
www.customautosounds.com/faq.html

This is the electrical circuit law that states that V=IR. That is, the electric potential (in volts) equals the current (in amperes) times the resistance (in ohms).
www.satellite-tv-hq.com/telecom-glossary-o.htm

states that the current in a metallic conductor is equal to the potential difference between the ends of the conductor divided by its resistance; symbolically, I = V/R.
www.dac.neu.edu/physics/b.maheswaran/phy1121/data/glos/gloss...

An equation that expresses the relationship between voltage, current and resistance in an electrical circuit. The equation can be expressed as follows: Volts (V) = Amps (I) X Ohms (R).
www.dimensionsunlimited.com/Glossary.html

Physical law that defines electrical voltage in relation to current and resistance. Voltage (E in volts) is equal to Current (I in amps) multiplied by Resistance (R in ohms), or E = IR, or R = E/I, or I = E/R, etc. Output Current Limiting An output protection feature that limits the output current to a predetermined value in order to prevent damage to the power supply or the load under overload conditions. The supply is automatically restored to normal operation following the removal of the overload.
adm.lacitec.on.ca/~ymicha/mcours/mixte/glossaire.htm

electric current is directly proportional to voltage and inversely proportional to resistance; I = E/R
wordnet.princeton.edu/perl/webwn

Ohm's law, named after its discoverer Georg Ohm [[Ohm's law#References|[1]]], states that the potential difference (or voltage drop V) between the ends of a conductor (for example, a resistor R) and the current, (I) flowing through R are proportional at a given temperature: where V is the voltage and I is the current; the equation yields the proportionality constant R, which is the electrical resistance of the device.
en.wikipedia.org/wiki/Ohm%27s_law

PS: Ermx, why don't we just get back to the original post and discuss furthur on alternative ways to reach higher temps?

[Edited on 5-9-2005 by darkflame89]

vulture - 5-9-2005 at 07:19

Quote:

We're not the average fox news viewer who falls for even the most basic spin tactic.
If you look at the second post of this thread, you'll see I raised a point which I later asked to be explained by a question.

However, instead of simply replying to my question you decided to circumvent it and attack me personally.
It's unbelievable you can't even remember or read the first posts of this thread.

Furthermore, the only personal attacks are coming from your side:

Quote:

Don't bother trying to explain cooper pairs to unionized, his head is so big already it would explode.

Quote:

Too bad you claim this board is about science when really it is merely a forum for you to voice only that which you agree with.

Quote:

This entire thread is a mere creation by unionized to attack me and good old vulture is joining in like a pack of rabid jackals.

Furthermore, this is not the only thread where you show this behaviour. It's also very coincedental that threads you meddle with tend to explode. As an administrator it is my duty to keep everything within certain boundaries here.
I know trouble when I see it, from years of experience.

That's also why i'm having the vague suspicion that you, along with 12A7X are just here to stirr things up to the higher glory of yourselves.

So far, unionised has a much better record than you on this board. Considering the smearjobs he had to endure from your side, I think he took it rather lightly.

Maybe you should stop whining and look at yourself first. Most admins would have had you banned for those statements I quoted above before you could even blink your eyes.

unionised - 5-9-2005 at 09:06

"

If we want to consider what Ohm actually said, then his law is:

(Current Density) = (Conductivity) x (Electric Field Strength)

V = IR is actually the macroscopic version of his law.
"
Thanks for digging that out, I'd be grateful if you could supply a reference.
I'm not sure it matters.
If your first version of Ohm's law is right then R is a constant.
If the second version is right then R is a function of the field strength.
The second one is true (by deffinition) but almost useless.

I can equally state that the current is the product of the obtuseness and the square of the voltage. (This serves as the deffinition of "obtuseness"

Equally, it's the product of the awkwardness and the log of the |voltage|.
(likewise, awkwardness is defined such that this expression is true).
The important aspect of his law is that if you chose the first power of the voltage then, for many bits of wire etc. you get a (nearly) constant value of R.

The second deffinition, which does no more than state that threre is some relation between current and voltage, serves no purpose.

The first, where R is constant, actually gets used quite a lot.

I think you insult Ohm to say that he gave the second definition.

If you accept that Ohms law requires a direct proportionallity then what I said about it not applying to cells is true.

If you think of R as a variable then what, exactly can you use Ohm's law for?

I think that you have tried to move the goalposts by saying that R is a variable in V=IR- it then becomes true by deffinition. Unfortunately, it also becomes useless.
How could this version of Ohm's law be used to help design anything? it would all become a "suck it and see" approach

I can't see how changing from current to current density; voltage to field strength and conducance to resistance makes any real difference.

zoomer - 5-9-2005 at 09:43

Unionized, I hope you will take this for what it is, just some information. I do not have any beef with you or anyone else on this board.

Quote:

Originally posted by unionised
How could this version of Ohm's law be used to help design anything? it would all become a "suck it and see" approach

In semiconductor design, that's exactly what we do. We know the conductivity (the inverse of resistance) of silicon in gross terms. But as you point out, exactly determining a resistance beforehand that changes with an environment that changes with the resistance itself is a Catch-22. So we approximate the behavior, build a prototype, then test it to as many V/I curves as possible, and build a chart of the actual resistance. I used to have large volumes of nothing but conductance charts for Si+.001%Ga, Si+.002%Ga, etc. (Obviously now they are all on CD). As years go by, more and more is learned, and computer models get better and better, but they still need to take that first prototype into the lab and characterize the heck out of it. Most of the time, it's not quite what's expected, and some changes are almost always needed before production.

Z

unionised - 5-9-2005 at 11:04

It's interesting to know how these chips that the 21st century runs on are designed. (though I doubt the book was very interesting).
What I was refering to was the nightmare where, just because you raised the current, there wasn't any certainty that the voltage would rise, never mind that it would be in proportion.

sparkgap - 6-9-2005 at 00:30

Minor mathematical point of contention, unionised, but this in no way detracts from your main point:

"...There's a mathematical function to describe this called something like "Kronecker's Delta" an infinitely narrow, infinitely high spike with unit area..."

Nope, what you were referring to was the Dirac delta function, which has the properties you describe. Kronecker delta is a slightly different beast.

sparky (~_~)

unionised - 6-9-2005 at 09:34

OOps! wrong delta.
Glad to know that someone read what I posted.

zoomer - 6-9-2005 at 11:10

Actually, we chipheads were always excited when a new volume came out. WCIS.

It's all buried in the computer models now, though.

This thread has taken many directions, and I must confess to have lost track of the main issue. My apologies, but can you give another example of such a "nightmare scenario?"

Z

Twospoons - 6-9-2005 at 23:10

Myself, as an electronics engineer for 16 years, I only use 'ohm's law' in linear systems, which includes complex impedance. I can't use V=IxR to calculate the current through a diode. Its an exponential relationship. I= Isat x e ^ (-kT/V) is not ohm's law. Damn thats hard to type without superscripting!

It gets worse. There's a facinating little device called a tunnel diode. In this diode the junction doping is so sharp that the electrons are able to cross the depletion barrier by quantum tunnelling, without ever having enough energy to go over the barrier as required in a normal diode. They freakishly appear on the other side of the barrier simply because the probability function describing the orbital is significantly non-zero on the other side, because the barrier is very, very thin. In short, they can - so they do! The net result is that part of the V / I curve for a tunnel diode has negative slope - it behaves like a 'negative' resistance.

How's that for a 'nightmare'?

12AX7 - 7-9-2005 at 07:29

Idunno but it provides wonderfully precise triggering in my Tek 475.

Tim

unionised - 7-9-2005 at 09:51

I'd forgoten about tunnel diodes. They really make a mockery of the idea that V=IR.
This site
http://www.americanmicrosemi.com/tutorials/tunneldiode.htm
shows the V I curve. For some values of I there are 3 different Vs and presumably 3 different values for R.
Zoomer,
Quite a lot of things would count as that nightmare, the tunnel diode is one, how do you model a circuit where for a given cuurent there can be 3 possible values of V. It's not impossible but, compared to just V=IR, it's a nightmare.

[Edited on 7-9-2005 by unionised]

zoomer - 14-9-2005 at 12:25

(Apologies for the dropout, I've been away for a family medical emergency, everything's OK now.)

Gee, here I thought you were going to start with a tough one!

"Negative resistance" is something of a misnomer. Resistance (a molecular-level analogue to friction) is always positive, because the reverse would be "amplification," a something-for-nothing arrangement that modern physics laws frown on. N-res refers to the phenomenon where a material's resistance to electron flow is modified by applied EMF in such a way that the amount of current has an inverse reaction to changes in EMF, and not a direct correlation as with passive and "positive" semiconductor materials. The point here is that N-res refers to the curve (the trend of multiple values), and not the instantaneous R value itself at any single point.

There is a difference between the mathematical relationship between V, I & R, and the ability of humans to understand and use that relationship in complex situations. And in re-reading the thread again I wondered if that distinction is what people have been speaking to all along. The mathematical relationship between V, I & R is absolute and unchanging regardless of the situation, exactly the same way the length of the three legs of a triangle are always indivisibly linked. However, applying Ohm's Law is tricky if not impossible when dealing with active materials (semiconductors, e-cells, etc) and sometimes the only way to know the values for sure is to hook it up and measure it yourself.

unionized, if that's what you are saying then I agree with you 100%.

Z

IrC - 14-9-2005 at 17:06

It is what I had been trying to say.