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Something like
I think, has to be replaced by
With for Thomson-coefficient. Any comments on this? — Preceding unsigned comment added by 158.64.77.102 ( talk) 11:23, 16 June 2015 (UTC)
This is a very badly written article about a very interesting topic, a major re-write is long overdue:
PLease re-organize this article from basic principles (thermodynamics) ---> details.
Put all the integrals at the END of the article, where they actually mean something, so that a person interested in this topic can read the article in a LINEAR fashion, without having to crypto-analyze it.
Martin —Preceding unsigned comment added by 24.79.209.165 ( talk) 23:28, 22 July 2008 (UTC)
Joule heating has not been reversed, but is theoretically possible under the laws of thermodynamics ...and... The first term ρ J² is simply the Joule heating, which is not reversible
I've been working on a paper regarding thermoelectricity for a class, and it's taken me a while to get the factors straightened out in my own head. At this point, I think I can present the information fairly clearly. The peer review page doesn't seem to be there still, but I'll definitely be looking over the material here for suggestions on directions to take. -- Beakdan 16:52, 15 November 2007 (UTC)
I've commented out the link to " Two Utah teens invented a durable, clean, efficient air conditioner based on this principle" because the page has been removed. It is however available in the google cache, so I'm not sure if whoever added that would like to do something about it to keep it around, or not. - Scott Dial 02:08, 3 September 2005 (UTC)
How is the EMF generated and where does the engery for this come from?
I am also looking for the more fundamental reason for the effect as to why "hot" electrons want to move to "cold" area. Of course, electrons at higher temperatures will have more kinetic energy. However, this will be in all directions and therefore no net effect electrically, it does not seem to explain why the electrons move to the cooler area on average. I guess this is similar to gases, but it also seems that having a boundary (the end of the wire) is fundamental to giving any kind of direction, and suggests that it is the material properties at the boundary that controls effect, not necessarily where the temperature gradient occurs (which conflicts with the modern understanding). I guess the boundary effect could also propagate through the length of the wire to where the temperature gradient is, but it's not clear if this is the case, or possibly even both. Anyway it would be nice to have this explained or a link to an article. — Preceding unsigned comment added by 202.59.187.137 ( talk) 01:13, 9 August 2023 (UTC)
The first line of the description is incorrect. It was first discovered by Thomas Johann Seebeck in 1821. Not by Peltier in 1884. Seebeck was not even alive anymore in 1884. He died in 1881!
\\\\\
Here are some references you might find interesting.
The original reference for Seebeck's discovery is:
T. J. Seebeck, Magnetische Polarisation der Metalle und Erze durch Temperatur-Differenz, Abhandlungen der Königlichen Akademie der Wissenschaften zu Berlin (im Jahre 1825 gedruckt), S. 265-373, 1821.
This has illustrations just after the article.
This volume of the "Abhandlungen" was printed in 1825, but is for 1822-1823. The content of the article was presented before the Akademie in October, 1821.
The Akademie publications of the time were usually published some years after the initial work of an author. Very often one sees that the author presented his work to meeting of the Akademie (sitzugberichte = meeting reports) well before actual publication. Often slightly different versions would appear in other journals, notices etc. before the Akademie version went to print. This can be a bit confusing when working up citations.
The same material, with updates, is available online:
T. J. Seebeck Ueber die Magnetische Polarisation der Metalle und Erze durch Temperatur-Differenz, Annalen der Physik, (Poggendorff) Bd. 82, Heft 1, S. 1-20, Heft 2, S. 133-160, Heft 3, S. 253-286, 1826.
This is a three part article appearing in successive issues of volume 82. (The S in this citation is from the German Seite for page, Bd is from Band for volume, and heft means issue.)
The above article is from the Annalen right after Ludwig Wilhelm Gilbert (1769-1824) died and Johann Christian Poggendorff (1796-1877) took over as editor. Poggendorff renamed the journal Annalen der Physic und Chemie. In 1900, under Paul Karl Ludwig Drude (1863-1906), the name was changed back to Annalen der Physik. The numbering of the issues reflect the changes of editorship and this can be very confusing. In this case Seebeck's article appears before Poggendorff had his "neue reihe" where the issues were renumbered. This one missed the "mark of Poggendorff." Note that the online version uses a numbering for the entire existence of the publication and in this case it coincides.
Older journals are a pain to cite!
Zorpoid — Preceding unsigned comment added by Zorpoid ( talk • contribs) 20:07, 3 October 2016 (UTC)
" Electrons flow from the hot end to the cold end."
I am not so sure this is true. I think it depends on the type of conductors, so I am taking it out for now. Feel free to put it back if you know it is true. Omegatron
Just to make sure people know, I redirected thermoelectricity to here, although there might be other forms besides the peltier-seebeck kind?
Please double-check the polarity of my voltmeter in the diagram. I think it is right, but i am not terribly qualified. - Omegatron
Did Seebeck discover the voltage difference first or the current loop/compass first? - Omegatron 17:09, Apr 2, 2004 (UTC)
I would like to show that these are functions of T, but
are all ugly. - Omegatron 20:25, Jul 5, 2004 (UTC)
I forgot which one it was but, why did you take off the change carrier diffusion/phonon drag picture? lol, I would not have read that paragraph or two if the picture didn't catch my attention. -- Mac Davis 11:13, 9 Jan 2005 (UTC)
Is pyroelectricity the same phenomenon as the seebeck effect?
I think that this page can be put in three:
Like you can see all those pages are already here, and making Peltier-Seebeck effect page in three part will just ask to remove the redirect and put part of article in. In fact main matter of having on page insted of three is that links to the others languages are falses, and that make bots from others' wiki copying bad links and put mess in link between the wikis. So I think that is a good thing to make this page become three. Please say what you think about it? Oliviosu 17:10, 10 July 2005 (UTC)
For this time I set this page as if it was Peltier effect page by deleting links to Thermoelectricity that are aleredy in Thermoelectricity page, I also set nl language link to the nl peltier page insted of nl seebeck page because all links to other wiki are to the peltier effect pages and making that allow bot to work without putting mess. Oliviosu 17:28, 10 July 2005 (UTC)
An article [2] on the Peltier effect was posted to slashdot.org recently. There are no links to this page, but I think that should account for the reoccurring vandalism.
From the article on 20050904, Superconductors have zero thermopower, and can be used to make thermocouples. Should that read, "... and can't be used to make thermocouples." It seems to me that with no voltage drop, there can be no temperature drop either. If it means that they can be used in conjunction with other materials to make thermocouples, then I still think it's a bit confusing.
can somebody translate the article to common english? the language used is CRAP. the author of the article should ask him/herself: for what kind of audience am i writing?! answer: OH, I AM WRITING IT FOR EVERYONE ON THIS PLANET FROM THE MOST DUMB TO THE MOST INTELLIGENT! noone wants to decipher an article before one is able to read it.
The Wikipedia article describing the Seebeck effect (see above) suggests that it was Thomas Johann Seebeck who discovered that "a voltage existed between two ends of a metal bar when a temperature gradient existed in the bar".
However, it is more likely the case that Seebeck never actually knew that this fact was true. The explanation for this is as follows:
Textbooks often propose that there are only three fundamental thermoelectric effects, however it is in fact possible to describe four.
The four thermoelectric effects, listed in chronological order of their discovery, are:
Effect 1 - If two different conductors are joined and the two junctions are maintained at different temperatures, an electromotive force is developed in the circuit.
Effect 2 - If a current flows in a circuit consisting of two different conductors then one of the junctions is heated and the other is cooled.
Effect 3 - When a temperature difference exists between two points in a single electrical conductor an electrical potential is established between the points.
Effect 4 - If a current passes through a conductor in which a temperature gradient exists, this current causes a flow of heat from one part to the other.
These effects are obviously very closely related. Indeed, each of them represents a reversible effect whereby effects 1 and 2 are the reverse of each other and, similarly, effects 3 and 4 are the reverse of each other.
Thomas Johann Seebeck first identified Effect 1 in 1821. He spent the rest of his scientific career measuring the size of this effect for different pairs of dissimilar conductors in contact with each other. Seebeck died in 1831.
In 1834 Jean Charles Athanase Peltier first identified Effect 2, the reverse of Effect 1. Peltier died in 1845.
Significantly later (around 1854-1855), William Thomson first deduced and demonstrated BOTH of the effects numbered 3 and 4.
Starling and Woodall describe part of Thomson's contribution thus (from "Physics", Longmans, 1950):
"He [Thomson] suggested that there must be other electromotive forces in the circuit and that these exist in the metals themselves, acting between the parts of any one metal at different temperatures. This was found to be correct. Thus if two points in the metal differ in temperature by the amount dT, the electromotive force in this element of the metal is s.dT. The quantity s is called the Thomson coefficient. It is taken to be positive when directed from points of lower to points of higher temperature."
As a result of the above, the four thermoelectric effects are correctly attributed the following names:
Effect 1 is the Seebeck effect.
Effect 2 is the Peltier effect - and is correctly identified as the reverse of the Seebeck effect.
Effects 3 and 4 together comprise both "directions" of the Thomson effect.
Some recent sources restrict the definition of the Thomson effect to that of Effect 4 only, and this may be either the cause or the result of a further tendency to prefer that the definition of the Seebeck effect may be satisfied by that of Effect 3 (with the possible consequence that Effect 1 is rendered anonymous).
Again, it is clear that the relationship between Effect 1 and Effect 3 must be a very close one.
However, it has been demonstrated that during his lifetime Thomas Johann Seebeck could not ever have been explicitly aware of Effect 3.
Furthermore, in the effect which Seebeck spent the greater part of his career measuring, when the junctions between the dissimilar metals are maintained at different temperatures a net electromotive force exists in the circuit which causes a current to flow around it. Such a circuit cannot be constructed with a single conductor, and therefore the definition of Effect 3 may not serve as an adequate explanation for the Seebeck effect.
It is not necessarily erroneous to say that there are only three thermoelectric effects, so long as it is understood that one of them, the Thomson effect, comprises both "directions" of the reversible effect; and that one of the others, the Seebeck effect, is the reverse of the Peltier effect and requires at least two dissimilar conductors to produce.
References: "Physics", Starling and Woodall, Longmans, 1950; "The Penguin Dictionary of Physics", Revised for the third edition by J P Cullerne B.Sc. D.Phil.
The Good article nomination for Thermoelectric effect has failed, for the following reason(s):
Shame that this article is considered too technical for a general audience to understand! As a general reader I found it brilliant, clearly expressed and utterly fascinating. Maybe the world itself should be rewritten in a less complex form, so that some grumpy lazy people don't have to work at understanding it.
I think this needs to point out in order to work the two metals need to have significatly different work functions. Otherwise the current itself will cause more heating than the cold end can compensate for.
Hello, I am new, but trying to be bold. I thought that "thermal" made a lot more sense than "heat" in the first sentence of the article since heat is not a quantity in the static sense, only as a flow. The old Caloric theory would say otherwise but it has of course been superceded. I think that the passage both makes more technical sense this way and the high school science educated reader can still understand it. Feel free to revert and discuss, I won't be offended! Wes Hermann 02:37, 5 December 2006 (UTC)
I made some big changes in the intro, and the biggest one is that Joule heating is no longer identified as being a TE effect. I know it's related, and if you want to parse "thermoelectric" it seems like JH would be part of it (this is a semantic error that formerly plagued the thermoelectricity article), but in common scientific parlance, Joule heating is not usually considered a TE effect. It's extremely common to draw a dichotomy between thermoelectric and Joule/Ohmic behavior in the technical literature. As the article notes, reversibility is a key difference here. Tarchon 19:57, 30 October 2007 (UTC)
The Link to related sites below contains a link which cannot be loaded:
Kind regards, Sebastian Morkisch -- S.Morkisch ( talk) 21:22, 10 April 2008 (UTC)
I think the image "Thermoelectric Cooler Diagram.svg" is wrong, because it shows current coming out of the positive terminal of a battery and going into the negative terminal. Charges should be moving out from the negative and into the positive terminal. —Preceding unsigned comment added by 151.196.139.68 ( talk) 23:05, 14 May 2008 (UTC)
Who is the admin of this page? I would like to discuss the future of the [*thermo*elec*] pages. -- Parthiban Santhanam ( talk) 00:43, 28 July 2008 (UTC)
Nextreme has come out with an evaluation power generation kit based on the Seebeck effect. Current page as of 2008-Dec-18 is: http://www.nextreme.com/pages/products/etegkit.html. I considered posting this to the main page in a "Related Links" section, but thought I should put it here for discussion for 2 reasons:
The article states the carnot efficiency is very low, between 0.3 and 0.6. Isn't this actually ranging from 'OK' to 'good' if you compare it to car engines or power stations? I've removed the very low comment. 130.88.67.204 ( talk) 11:17, 14 August 2009 (UTC)
The Kelvin Probe is probing the Work-function. Though there are a few books and articles that interpret the Seebecke-effect as the temperature dependence of the work function - this is just not correct. The Seebecke-effect is a bulk effect, while the work function depends on surface properties like adsorbed gas as well. So the Kelvin Probe will show something different that the thermal EMV. In addition the resolution of normal Kelvin Probes is just not sufficient for voltages in the µV range. So it's probably better not to mention the Kelvin Probe int this articel.-- Ulrich67 ( talk) 16:53, 3 January 2011 (UTC)
If power is applied to a peltier, upon disconnection there should be a potential difference between the terminals, but which polarity? Does it work like a battery, where positive voltage is applied to the positive terminal when charging? Or does current flow in the same direction after a power supply is exchanged for a load. The second coloured diagram in the article has no polarity marked. — Preceding unsigned comment added by 60.241.100.51 ( talk) 10:38, 13 December 2011 (UTC)
The term Seebeck coefficient is used in the Seebeck effect section but never defined. I think I can infer what it means from the context, but I would be a lot more certain of my understanding if it was clearly defined in the section. -- Kierkkadon talk/ contribs 22:12, 29 January 2013 (UTC)
The article is lacking a discussion of unwanted thermelectric effects, for example in precision voltage measurements. How to overcome it, maybe by using materials or material combinations that have a small thermoelectric effect? Starblue ( talk) 17:30, 13 October 2013 (UTC) Document with some good info from Keithley: Making Precision Low Voltage and Low Resistance Measurements Starblue ( talk) 18:43, 13 October 2013 (UTC)
I defy anyone to find the Thomson (Kelvin) Relations in Thomson's writings. They may be based upon equations in "On The Dynamical Theory Of Heat," but look throughout his complete works and you will not find the Relations. I have been unable to find any discussions of them in late 19th and early 20th Century writings on thermoelectrics, either. They do not seem to emerge until around the time that Lars Onsager introduced his work on reciprocal relations in the 1930's. The Relations appear to grow out of 20th Century work in thermodynamics and discussion of the Thomson Relations takes off from there.
It should also be noted that the Relation linking the Peltier and Seebeck coefficients through absolute temperature (π = αT), is invalid. Solid state theory shows us that the Peltier coefficient is actually dependent upon two materials: 1) the junction-to-junction material establishing the energy level for transport (at the conduction or valence band in TE materials), and 2) the conductor at each junction (usually plated copper) which conducts electrons in proximity to its Fermi level. It is the transition between these levels which determines the amount of heat absorbed or released. That quantity is π•I where π is both the Peltier coefficient and the difference in energy (in Joules per Coulomb) between the Fermi level of the conductor at the junction, and the conduction or valence band of the junction-to-junction conductor. Because the Peltier coefficient actually reflects the properties of two materials, it cannot possibly be derived from the Seebeck coefficient of the junction-to-junction conductor (which has a value independent of any other materials) and the absolute temperature. The Relation is invalid. By the way, even though there are no junction conductors present along the length of the junction-to-junction conductor, the Fermi level remains relevant in understanding how the quantity of heat at any point, relates to the activity at the junctions. The temperature dependency of the Fermi level creates a virtual base line and the Peltier coefficient remains important in the mathematics of absorption, transport, and release throughout the length of a TE element.
This and a lengthy proof showing that Thomson Effect was not adequately demonstrated(based on flaws in Thomson's proof, an alternate thesis not explored, and his failure to sufficiently examine the other effects), will be in my upcoming book, Rethinking Thermoelectric Fundamentals Within A Temperature Dependent Context (Michael Spry), intended for release in 2016.
Observing thermocouple data, for example in Wikipedia's "Thermocouple", Seebeck voltage is nearly proportional to the temperature difference between the junctions for a large range of temperatures. That is, Seebeck coefficient is nearly temperature independent. Then according to Thomson Relations, see Article, Thomson coefficient is nearly zero for such ranges. On the other hand the heat content of charge carriers is temperature dependent, in many cases nearly proportional to the temperature. Therefore, when a charge carrier flows along a temperature gradient, it must deliver heat to its vicinity or absorb heat from it, that is, Thomson coefficient cannot be zero even for ranges where Seebeck coefficient is temperature independent.
This observation seems to support the paragraph above, that Kelvin did not invent Thomson (Kelvin) relations. ( Urila ( talk) 15:34, 2 February 2017 (UTC))
See "Practical color photography" by Wall, E. J. Chapter XV [1] Where he attributes to J. T. Seebeck the discovery that the action of light on silver chloride under the influence of the spectral rays assumed the colors incident on it, which has been attributed to Alexandre-Edmond Becquerel in work he published more than 30 years later. Is Wall correct, does the document sent to Goethe exist to prove this beyond question?
References
The article could benefit from noting other common applications. In absorption spectroscopy, a laser emitting diode is cooled using the Peltier effect, with the current going to the TEC proportional to the amount of cooling, if any, needed to maintain a constant LED temperature. A feedback thermocouple is used to determine the current needed to drive the TEC to maintain constant LED temperature with great accuracy. Laser emitting diodes rely upon temperature and current to determine their output frequency, and very tightly-controlled temperature of the LED means high accuracy in spectroscopic measurements.
Spy satellite optical and IR imagery also use TE Cooling devices to keep their detector junction arrays cold since nuclear power is long-lived and cheap on satellites whereas cryogenic fluids must be replaced on spacecraft which gets expensive and takes the craft off line during the process. SoftwareThing ( talk) 22:37, 24 September 2018 (UTC)
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Something like
I think, has to be replaced by
With for Thomson-coefficient. Any comments on this? — Preceding unsigned comment added by 158.64.77.102 ( talk) 11:23, 16 June 2015 (UTC)
This is a very badly written article about a very interesting topic, a major re-write is long overdue:
PLease re-organize this article from basic principles (thermodynamics) ---> details.
Put all the integrals at the END of the article, where they actually mean something, so that a person interested in this topic can read the article in a LINEAR fashion, without having to crypto-analyze it.
Martin —Preceding unsigned comment added by 24.79.209.165 ( talk) 23:28, 22 July 2008 (UTC)
Joule heating has not been reversed, but is theoretically possible under the laws of thermodynamics ...and... The first term ρ J² is simply the Joule heating, which is not reversible
I've been working on a paper regarding thermoelectricity for a class, and it's taken me a while to get the factors straightened out in my own head. At this point, I think I can present the information fairly clearly. The peer review page doesn't seem to be there still, but I'll definitely be looking over the material here for suggestions on directions to take. -- Beakdan 16:52, 15 November 2007 (UTC)
I've commented out the link to " Two Utah teens invented a durable, clean, efficient air conditioner based on this principle" because the page has been removed. It is however available in the google cache, so I'm not sure if whoever added that would like to do something about it to keep it around, or not. - Scott Dial 02:08, 3 September 2005 (UTC)
How is the EMF generated and where does the engery for this come from?
I am also looking for the more fundamental reason for the effect as to why "hot" electrons want to move to "cold" area. Of course, electrons at higher temperatures will have more kinetic energy. However, this will be in all directions and therefore no net effect electrically, it does not seem to explain why the electrons move to the cooler area on average. I guess this is similar to gases, but it also seems that having a boundary (the end of the wire) is fundamental to giving any kind of direction, and suggests that it is the material properties at the boundary that controls effect, not necessarily where the temperature gradient occurs (which conflicts with the modern understanding). I guess the boundary effect could also propagate through the length of the wire to where the temperature gradient is, but it's not clear if this is the case, or possibly even both. Anyway it would be nice to have this explained or a link to an article. — Preceding unsigned comment added by 202.59.187.137 ( talk) 01:13, 9 August 2023 (UTC)
The first line of the description is incorrect. It was first discovered by Thomas Johann Seebeck in 1821. Not by Peltier in 1884. Seebeck was not even alive anymore in 1884. He died in 1881!
\\\\\
Here are some references you might find interesting.
The original reference for Seebeck's discovery is:
T. J. Seebeck, Magnetische Polarisation der Metalle und Erze durch Temperatur-Differenz, Abhandlungen der Königlichen Akademie der Wissenschaften zu Berlin (im Jahre 1825 gedruckt), S. 265-373, 1821.
This has illustrations just after the article.
This volume of the "Abhandlungen" was printed in 1825, but is for 1822-1823. The content of the article was presented before the Akademie in October, 1821.
The Akademie publications of the time were usually published some years after the initial work of an author. Very often one sees that the author presented his work to meeting of the Akademie (sitzugberichte = meeting reports) well before actual publication. Often slightly different versions would appear in other journals, notices etc. before the Akademie version went to print. This can be a bit confusing when working up citations.
The same material, with updates, is available online:
T. J. Seebeck Ueber die Magnetische Polarisation der Metalle und Erze durch Temperatur-Differenz, Annalen der Physik, (Poggendorff) Bd. 82, Heft 1, S. 1-20, Heft 2, S. 133-160, Heft 3, S. 253-286, 1826.
This is a three part article appearing in successive issues of volume 82. (The S in this citation is from the German Seite for page, Bd is from Band for volume, and heft means issue.)
The above article is from the Annalen right after Ludwig Wilhelm Gilbert (1769-1824) died and Johann Christian Poggendorff (1796-1877) took over as editor. Poggendorff renamed the journal Annalen der Physic und Chemie. In 1900, under Paul Karl Ludwig Drude (1863-1906), the name was changed back to Annalen der Physik. The numbering of the issues reflect the changes of editorship and this can be very confusing. In this case Seebeck's article appears before Poggendorff had his "neue reihe" where the issues were renumbered. This one missed the "mark of Poggendorff." Note that the online version uses a numbering for the entire existence of the publication and in this case it coincides.
Older journals are a pain to cite!
Zorpoid — Preceding unsigned comment added by Zorpoid ( talk • contribs) 20:07, 3 October 2016 (UTC)
" Electrons flow from the hot end to the cold end."
I am not so sure this is true. I think it depends on the type of conductors, so I am taking it out for now. Feel free to put it back if you know it is true. Omegatron
Just to make sure people know, I redirected thermoelectricity to here, although there might be other forms besides the peltier-seebeck kind?
Please double-check the polarity of my voltmeter in the diagram. I think it is right, but i am not terribly qualified. - Omegatron
Did Seebeck discover the voltage difference first or the current loop/compass first? - Omegatron 17:09, Apr 2, 2004 (UTC)
I would like to show that these are functions of T, but
are all ugly. - Omegatron 20:25, Jul 5, 2004 (UTC)
I forgot which one it was but, why did you take off the change carrier diffusion/phonon drag picture? lol, I would not have read that paragraph or two if the picture didn't catch my attention. -- Mac Davis 11:13, 9 Jan 2005 (UTC)
Is pyroelectricity the same phenomenon as the seebeck effect?
I think that this page can be put in three:
Like you can see all those pages are already here, and making Peltier-Seebeck effect page in three part will just ask to remove the redirect and put part of article in. In fact main matter of having on page insted of three is that links to the others languages are falses, and that make bots from others' wiki copying bad links and put mess in link between the wikis. So I think that is a good thing to make this page become three. Please say what you think about it? Oliviosu 17:10, 10 July 2005 (UTC)
For this time I set this page as if it was Peltier effect page by deleting links to Thermoelectricity that are aleredy in Thermoelectricity page, I also set nl language link to the nl peltier page insted of nl seebeck page because all links to other wiki are to the peltier effect pages and making that allow bot to work without putting mess. Oliviosu 17:28, 10 July 2005 (UTC)
An article [2] on the Peltier effect was posted to slashdot.org recently. There are no links to this page, but I think that should account for the reoccurring vandalism.
From the article on 20050904, Superconductors have zero thermopower, and can be used to make thermocouples. Should that read, "... and can't be used to make thermocouples." It seems to me that with no voltage drop, there can be no temperature drop either. If it means that they can be used in conjunction with other materials to make thermocouples, then I still think it's a bit confusing.
can somebody translate the article to common english? the language used is CRAP. the author of the article should ask him/herself: for what kind of audience am i writing?! answer: OH, I AM WRITING IT FOR EVERYONE ON THIS PLANET FROM THE MOST DUMB TO THE MOST INTELLIGENT! noone wants to decipher an article before one is able to read it.
The Wikipedia article describing the Seebeck effect (see above) suggests that it was Thomas Johann Seebeck who discovered that "a voltage existed between two ends of a metal bar when a temperature gradient existed in the bar".
However, it is more likely the case that Seebeck never actually knew that this fact was true. The explanation for this is as follows:
Textbooks often propose that there are only three fundamental thermoelectric effects, however it is in fact possible to describe four.
The four thermoelectric effects, listed in chronological order of their discovery, are:
Effect 1 - If two different conductors are joined and the two junctions are maintained at different temperatures, an electromotive force is developed in the circuit.
Effect 2 - If a current flows in a circuit consisting of two different conductors then one of the junctions is heated and the other is cooled.
Effect 3 - When a temperature difference exists between two points in a single electrical conductor an electrical potential is established between the points.
Effect 4 - If a current passes through a conductor in which a temperature gradient exists, this current causes a flow of heat from one part to the other.
These effects are obviously very closely related. Indeed, each of them represents a reversible effect whereby effects 1 and 2 are the reverse of each other and, similarly, effects 3 and 4 are the reverse of each other.
Thomas Johann Seebeck first identified Effect 1 in 1821. He spent the rest of his scientific career measuring the size of this effect for different pairs of dissimilar conductors in contact with each other. Seebeck died in 1831.
In 1834 Jean Charles Athanase Peltier first identified Effect 2, the reverse of Effect 1. Peltier died in 1845.
Significantly later (around 1854-1855), William Thomson first deduced and demonstrated BOTH of the effects numbered 3 and 4.
Starling and Woodall describe part of Thomson's contribution thus (from "Physics", Longmans, 1950):
"He [Thomson] suggested that there must be other electromotive forces in the circuit and that these exist in the metals themselves, acting between the parts of any one metal at different temperatures. This was found to be correct. Thus if two points in the metal differ in temperature by the amount dT, the electromotive force in this element of the metal is s.dT. The quantity s is called the Thomson coefficient. It is taken to be positive when directed from points of lower to points of higher temperature."
As a result of the above, the four thermoelectric effects are correctly attributed the following names:
Effect 1 is the Seebeck effect.
Effect 2 is the Peltier effect - and is correctly identified as the reverse of the Seebeck effect.
Effects 3 and 4 together comprise both "directions" of the Thomson effect.
Some recent sources restrict the definition of the Thomson effect to that of Effect 4 only, and this may be either the cause or the result of a further tendency to prefer that the definition of the Seebeck effect may be satisfied by that of Effect 3 (with the possible consequence that Effect 1 is rendered anonymous).
Again, it is clear that the relationship between Effect 1 and Effect 3 must be a very close one.
However, it has been demonstrated that during his lifetime Thomas Johann Seebeck could not ever have been explicitly aware of Effect 3.
Furthermore, in the effect which Seebeck spent the greater part of his career measuring, when the junctions between the dissimilar metals are maintained at different temperatures a net electromotive force exists in the circuit which causes a current to flow around it. Such a circuit cannot be constructed with a single conductor, and therefore the definition of Effect 3 may not serve as an adequate explanation for the Seebeck effect.
It is not necessarily erroneous to say that there are only three thermoelectric effects, so long as it is understood that one of them, the Thomson effect, comprises both "directions" of the reversible effect; and that one of the others, the Seebeck effect, is the reverse of the Peltier effect and requires at least two dissimilar conductors to produce.
References: "Physics", Starling and Woodall, Longmans, 1950; "The Penguin Dictionary of Physics", Revised for the third edition by J P Cullerne B.Sc. D.Phil.
The Good article nomination for Thermoelectric effect has failed, for the following reason(s):
Shame that this article is considered too technical for a general audience to understand! As a general reader I found it brilliant, clearly expressed and utterly fascinating. Maybe the world itself should be rewritten in a less complex form, so that some grumpy lazy people don't have to work at understanding it.
I think this needs to point out in order to work the two metals need to have significatly different work functions. Otherwise the current itself will cause more heating than the cold end can compensate for.
Hello, I am new, but trying to be bold. I thought that "thermal" made a lot more sense than "heat" in the first sentence of the article since heat is not a quantity in the static sense, only as a flow. The old Caloric theory would say otherwise but it has of course been superceded. I think that the passage both makes more technical sense this way and the high school science educated reader can still understand it. Feel free to revert and discuss, I won't be offended! Wes Hermann 02:37, 5 December 2006 (UTC)
I made some big changes in the intro, and the biggest one is that Joule heating is no longer identified as being a TE effect. I know it's related, and if you want to parse "thermoelectric" it seems like JH would be part of it (this is a semantic error that formerly plagued the thermoelectricity article), but in common scientific parlance, Joule heating is not usually considered a TE effect. It's extremely common to draw a dichotomy between thermoelectric and Joule/Ohmic behavior in the technical literature. As the article notes, reversibility is a key difference here. Tarchon 19:57, 30 October 2007 (UTC)
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Kind regards, Sebastian Morkisch -- S.Morkisch ( talk) 21:22, 10 April 2008 (UTC)
I think the image "Thermoelectric Cooler Diagram.svg" is wrong, because it shows current coming out of the positive terminal of a battery and going into the negative terminal. Charges should be moving out from the negative and into the positive terminal. —Preceding unsigned comment added by 151.196.139.68 ( talk) 23:05, 14 May 2008 (UTC)
Who is the admin of this page? I would like to discuss the future of the [*thermo*elec*] pages. -- Parthiban Santhanam ( talk) 00:43, 28 July 2008 (UTC)
Nextreme has come out with an evaluation power generation kit based on the Seebeck effect. Current page as of 2008-Dec-18 is: http://www.nextreme.com/pages/products/etegkit.html. I considered posting this to the main page in a "Related Links" section, but thought I should put it here for discussion for 2 reasons:
The article states the carnot efficiency is very low, between 0.3 and 0.6. Isn't this actually ranging from 'OK' to 'good' if you compare it to car engines or power stations? I've removed the very low comment. 130.88.67.204 ( talk) 11:17, 14 August 2009 (UTC)
The Kelvin Probe is probing the Work-function. Though there are a few books and articles that interpret the Seebecke-effect as the temperature dependence of the work function - this is just not correct. The Seebecke-effect is a bulk effect, while the work function depends on surface properties like adsorbed gas as well. So the Kelvin Probe will show something different that the thermal EMV. In addition the resolution of normal Kelvin Probes is just not sufficient for voltages in the µV range. So it's probably better not to mention the Kelvin Probe int this articel.-- Ulrich67 ( talk) 16:53, 3 January 2011 (UTC)
If power is applied to a peltier, upon disconnection there should be a potential difference between the terminals, but which polarity? Does it work like a battery, where positive voltage is applied to the positive terminal when charging? Or does current flow in the same direction after a power supply is exchanged for a load. The second coloured diagram in the article has no polarity marked. — Preceding unsigned comment added by 60.241.100.51 ( talk) 10:38, 13 December 2011 (UTC)
The term Seebeck coefficient is used in the Seebeck effect section but never defined. I think I can infer what it means from the context, but I would be a lot more certain of my understanding if it was clearly defined in the section. -- Kierkkadon talk/ contribs 22:12, 29 January 2013 (UTC)
The article is lacking a discussion of unwanted thermelectric effects, for example in precision voltage measurements. How to overcome it, maybe by using materials or material combinations that have a small thermoelectric effect? Starblue ( talk) 17:30, 13 October 2013 (UTC) Document with some good info from Keithley: Making Precision Low Voltage and Low Resistance Measurements Starblue ( talk) 18:43, 13 October 2013 (UTC)
I defy anyone to find the Thomson (Kelvin) Relations in Thomson's writings. They may be based upon equations in "On The Dynamical Theory Of Heat," but look throughout his complete works and you will not find the Relations. I have been unable to find any discussions of them in late 19th and early 20th Century writings on thermoelectrics, either. They do not seem to emerge until around the time that Lars Onsager introduced his work on reciprocal relations in the 1930's. The Relations appear to grow out of 20th Century work in thermodynamics and discussion of the Thomson Relations takes off from there.
It should also be noted that the Relation linking the Peltier and Seebeck coefficients through absolute temperature (π = αT), is invalid. Solid state theory shows us that the Peltier coefficient is actually dependent upon two materials: 1) the junction-to-junction material establishing the energy level for transport (at the conduction or valence band in TE materials), and 2) the conductor at each junction (usually plated copper) which conducts electrons in proximity to its Fermi level. It is the transition between these levels which determines the amount of heat absorbed or released. That quantity is π•I where π is both the Peltier coefficient and the difference in energy (in Joules per Coulomb) between the Fermi level of the conductor at the junction, and the conduction or valence band of the junction-to-junction conductor. Because the Peltier coefficient actually reflects the properties of two materials, it cannot possibly be derived from the Seebeck coefficient of the junction-to-junction conductor (which has a value independent of any other materials) and the absolute temperature. The Relation is invalid. By the way, even though there are no junction conductors present along the length of the junction-to-junction conductor, the Fermi level remains relevant in understanding how the quantity of heat at any point, relates to the activity at the junctions. The temperature dependency of the Fermi level creates a virtual base line and the Peltier coefficient remains important in the mathematics of absorption, transport, and release throughout the length of a TE element.
This and a lengthy proof showing that Thomson Effect was not adequately demonstrated(based on flaws in Thomson's proof, an alternate thesis not explored, and his failure to sufficiently examine the other effects), will be in my upcoming book, Rethinking Thermoelectric Fundamentals Within A Temperature Dependent Context (Michael Spry), intended for release in 2016.
Observing thermocouple data, for example in Wikipedia's "Thermocouple", Seebeck voltage is nearly proportional to the temperature difference between the junctions for a large range of temperatures. That is, Seebeck coefficient is nearly temperature independent. Then according to Thomson Relations, see Article, Thomson coefficient is nearly zero for such ranges. On the other hand the heat content of charge carriers is temperature dependent, in many cases nearly proportional to the temperature. Therefore, when a charge carrier flows along a temperature gradient, it must deliver heat to its vicinity or absorb heat from it, that is, Thomson coefficient cannot be zero even for ranges where Seebeck coefficient is temperature independent.
This observation seems to support the paragraph above, that Kelvin did not invent Thomson (Kelvin) relations. ( Urila ( talk) 15:34, 2 February 2017 (UTC))
See "Practical color photography" by Wall, E. J. Chapter XV [1] Where he attributes to J. T. Seebeck the discovery that the action of light on silver chloride under the influence of the spectral rays assumed the colors incident on it, which has been attributed to Alexandre-Edmond Becquerel in work he published more than 30 years later. Is Wall correct, does the document sent to Goethe exist to prove this beyond question?
References
The article could benefit from noting other common applications. In absorption spectroscopy, a laser emitting diode is cooled using the Peltier effect, with the current going to the TEC proportional to the amount of cooling, if any, needed to maintain a constant LED temperature. A feedback thermocouple is used to determine the current needed to drive the TEC to maintain constant LED temperature with great accuracy. Laser emitting diodes rely upon temperature and current to determine their output frequency, and very tightly-controlled temperature of the LED means high accuracy in spectroscopic measurements.
Spy satellite optical and IR imagery also use TE Cooling devices to keep their detector junction arrays cold since nuclear power is long-lived and cheap on satellites whereas cryogenic fluids must be replaced on spacecraft which gets expensive and takes the craft off line during the process. SoftwareThing ( talk) 22:37, 24 September 2018 (UTC)