This page is an archive of past discussions. Do not edit the contents of this page. If you wish to start a new discussion or revive an old one, please do so on the current talk page. |
After searching other locations, I'm finding very different versions of resistivity for Al. Something closer to 2.6 or 2.8 rather than 2.282... -- Hobit 14:19, 11 October 2005 (UTC)
The table of resistivity values looks exactly like the one in my physics textbook (Physics for Scientists and Engineers, with Modern Physics by Serway and Jewett). Is there a missing citation here or am I missing something? Mahsmanj
Material | Resistivity (ohm metres) | Temperature coefficient per kelvin |
---|---|---|
Chromium | 1.8 × 10-7 | .0000059 |
Tin | 1.15 × 10-5 | .0042 |
Silver, German | 3.3 × 10-5 | .0004 |
Seawater | 2.0 × 10-1 [1] | ? |
Pure water | 2.5 × 105 | ? |
Human skin | approximately 5.0 × 105 | ? |
German silver is also known as nickel silver. If you look for the resistivity nickel silver instead of german silver, you will have better luck finding a source. -Rudy
Does anybody know how resistivity relates to the volume of an object? That is, if I had something that looked more like a sphere than a thin wire, and wanted to calculate its resistance using its resistivity, how would I do it?
It probably involves integrals, though I don't know if the equations are straightforward. Remember that this isn't a straight volume or surface area type calculation. You're calculating the resistance of the object, but the resistance will be different for the same object depending on how the electrodes are arranged. Would you have to calculate the current flow through each differential cross section of the entire object? This gets into bulk resistance calculations that I am not familiar with (but would like to be). — Omegatron 19:00, 24 February 2007 (UTC)
19:59, 2 July 2007 (UTC)19:59, 2 July 2007 (UTC) 155.104.37.17 19:59, 2 July 2007 (UTC) Sorry to add here, but I'm not seeing any better way to add a comment to the page.
Resistivity may also change under many conditions besides temperature. Humidity, for instance, as a material absorbs water, or even in a vacuum, where it outgasses whatever material. This is an effect we have seen before - nylon is a good example, it's resistivity goes up under a vacuum.
I think it would be better if we combined the tables of resistivity and conductivity since they are so fundamentally linked. Please discuss this at Talk:Electrical conductivity. Fresheneesz 22:52, 27 May 2006 (UTC)
somebody has just defaced the general equation: it should be rho=R multiplied by A divided by length
I have changed it twice but someone keeps changing it back. It should be
and not
I do not make out that I understand everything that is involved with resistivity as I am only a year 11 pupil studying it for my GCSE but about this I am quite certain and I have also verified it with my teacher. Some one told me to check this up on an External sitewhich I did. There equation of
which can be rearranged to form
If anyone can explain why it should be the other way please try. Mrpowers999 16:16, 24 February 2007 (UTC)
which can be rearranged to form
which can be rearranged to form
Nov 27, 2007 I corrected the units for resistivity from Ohm-meters to Ohms per meter. —Preceding unsigned comment added by 206.104.31.54 ( talk) 01:24, 29 November 2007 (UTC)
NB: In the UK, Year 11 is the final year of compulsary education. Mrpowers999 will be either 15 or 16, NOT 11. This is because school starts at 4 or 5 (not birth) and the first school year is called reception. Anonymous —Preceding unsigned comment added by 79.71.27.222 ( talk) 18:23, 23 November 2008 (UTC)
I think either the table is wrong, or the values in the Silver, Copper and Gold articles are wrong. Also, considering that the resistivity is given with much less precision than the coefficient, it seems misleading to add 1.47... to ~.0038... and get ~1.4738.... Κσυπ Cyp 13:06, 23 April 2007 (UTC)
I get 2.45 for Al, 1.56 for Cu, 1.5 for Ag, 2.04 for Au, 4.9 for W, 8.9 for Fe, 9.8 for Pt, 19 for Pb (all 10^-8), supposedly for "commercially pure" samples between 288-298K. Revised Nuffield Advanced Science Book of Data, Addison Wesley Longman Limited. Presumably it varies greatly between samples. ⇌ Elektron 02:58, 1 September 2007 (UTC)
I don't dispute any of the values/coefficients in the table, but there is an error in the note: "*The numbers in this column increase or decrease the significand portion of the resistivity. For example, at 21°C (294.15 K), the resistivity of silver is 1.65×10^−8." Either this conductivity change was calculated for a 10°C (not 1°C) temp. change and the note should reflect such, or the coefficient used in the calculation was .038 instead of the proper value of .0038. Also, I think the simple relation Δρ = α ΔT ρ where α is the coef. is more clear than the phrase about the significand portion. Clcasto ( talk) 18:19, 3 January 2008 (UTC)
And why is this table not incorporated?: http://en.wikipedia.org/wiki/Electrical_resistivities_of_the_elements_(data_page) It seems to provide a full chart of all resistivities of all chemical elements... Seems pretty fundamental in any resistivity chart, don't you think? ;) —Preceding unsigned comment added by 62.131.171.23 ( talk) 21:04, 18 February 2008 (UTC)
Plus very suspicious value for calcium. As far I had deal with the calcite mollusc houses, calcite containing walls, calcite stone, cement, silicate brics etc calcium much containing materials them all are roughly good isolators. I suggess may be an author had criscrossed value 3E-8 with 3E+8???? Or value is given for naturally flooded carbonites deep under soil, thus the water is that agent making so strange resistance??? —Preceding unsigned comment added by 85.254.232.1 ( talk) 15:43, 30 March 2009 (UTC)
I updated the table for conductivity by simple calculation from the already present resistivity (no other change was made) EV1Te ( talk) 08:25, 28 April 2011 (UTC)
I'm sure the table is still wrong. Conductivity multiplied by resistivity is always 1. Eddietoran ( talk) 20:37, 22 August 2011 (UTC)
The temperature coefficient of resistivity for copper is 0.0039 everywhere but this page, where it is 0.0068. — Preceding unsigned comment added by Zxw 095 ( talk • contribs) 21:35, 29 March 2013 (UTC)
well, 1.56 for copper is quite good, I don't know how the guy did it, but around room temperature (18-21°C), bulk copper of high purity (99.9999% Cu) is supposed to be around 1.7-1.8 depending on the guy doing the experiment. so you'll understand that 1.56 renders me a bit suspicious of the whole book. for a scientifical / engineering point of view, 5% variation in resistivity may be very important, and 0.1% thermical variations are important as 100°C of heat during use is not unheard of, meaning that 0.1% or 0.2% per°C means either +10% or +20% resistivity, with may change all behaviours if you need precise input/output.
I had another information to add to the resistivity article, but I don't really have the time and the know-how to put it in the main article :
basically, resistivity is intrinseque to a material, depending on its atome (atomic properties such as masse, active surface...etc) then you add modifiers :
currently the size of both grains and sample really have impact on resistivity when the dimensions approche or are under the micrometer range, but maybe the fact should be mentionned, as well as impurity effects.
here are some articles (list is non exaustive)on what I'm saying (as I work mostly in mircoelectronics, those works deal with that subject, but more general links can maybe be found, I have some thesis reports, but mostly in french):
If someone wants to inclued those informations in this page, and can't find the information or want to discuss it, write in my user page, I will connect to it a bit in the near futur. Calavente ( talk) 01:22, 23 January 2008 (UTC)
Hey, in spanish wikipedia...
Material | Resistividad (en 20°C-25ºC) (Ω·m) |
---|---|
Plata [1] | 1.55 x 10-8 |
Cobre [2] | 1.70 x 10-8 |
Oro [3] | 2.22 x 10-8 |
Aluminio [4] | 2.82 x 10-8 |
Wolframio [5] | 5.65 x 10-8 |
Níquel [6] | 6.40 x 10-8 |
Hierro [7] | 8.90 x 10-8 |
Platino [8] | 10.60 x 10-8 |
Estaño [9] | 11.50 x 10-8 |
Acero inoxidable 301 [10] | 72.00 x 10-8 |
Grafito [11] | 60.00 x 10-8 |
Based on Matweb that I consider, good, for the resistivity article, we can be more accuracy in another dedicated only to the values.— Nicoguaro ( talk) 14:26, 1 April 2008 (UTC)
References
Is there anyway to get the table to meaningfully sort on resistivity? The current sort doesn't seem to grok scientific notation... -- Belg4mit ( talk) 01:54, 11 September 2008 (UTC)
Resistance and Resistivity for Selected Common Metals [2] 10-ga wire Resistance Ohms/ft Resistivity (10-6 ohm-cm) Silver 0.000944 1.629 Copper 0.000999 1.724 Gold 0.00114 2.44 Aluminum 0.00164 2.828 Iridium 0.00306 5.29 Brass 0.00406 7.00 Nickel 0.00452 7.8 Iron 0.00579 10.0 Platinum 0.00579 10.0 Steel 0.00684 11.8 Lead 0.0127 22
This article would be more useful to the general reader if more practical data like above were added. - 71.174.184.42 ( talk) 00:07, 21 May 2009 (UTC)
I checked the reference for copper that is listed in the table and the two numbers do not match. We should not list a reference with a different value, or even better we should list the correct value and a reference that verifies it. —Preceding unsigned comment added by 71.33.199.247 ( talk) 21:19, 26 March 2010 (UTC)
The "sort" option in tables doesn't seem to sort numbers, but instead sorts as strings - this makes it useless if using scientific notation or any number format that doesn't sort the same as strings. The "sort" function needs a stronger parser that can be told "These are numbers, not strings" and sort by magnitude of the number, not just as a string sort. -- Wtshymanski ( talk) 19:44, 10 February 2011 (UTC)
These edits [ [3]] seem to largely consist of changing the units or resistivity from Ωm to m/S and changing numerical notation from e.g. 58×106 to 58∘106. The use of m/S while technically correct is virtually unheard of (at least unheard of by Google). The dot-notation for simple arithmetic multiplication is also correct, but probably less common the than the cross. These edits are clearly made in good faith, but they are very extensive; is there anything good that in them that can be saved, or should they just be reverted completely? -- catslash ( talk) 11:16, 21 May 2011 (UTC)
In the table concerning conductivity and density, I feel like the product of the two parameters (what is given) is not as interesting as the quotient. A designer would be interested in conductivity per unit of mass, so you'd want resistivity/density. A high value would mean lots of conduction for a given mass. I think the given values, while correct, are not useful. — Preceding unsigned comment added by 128.196.211.58 ( talk) 22:43, 5 August 2011 (UTC)
some are in scientific notation (1.0x10^14), while some aren't (10x10^14). I do not know whether these were typed with the decimal forgotten, or if it's a different notation intentionally. Maybe someone could track down the poster? — Preceding unsigned comment added by 67.42.71.64 ( talk) 19:49, 9 June 2014 (UTC)
The entire left side of the table lists values in a strange format, viz.
Which I take to mean
... The whole table needs to be revised to reflect ordinary notation, as I wouldn't want anyone thinking we are using Euler's number here. I like to saw logs! ( talk) 06:12, 9 August 2011 (UTC)
Wtshymanski proposes a merge. We can discuss it here. -- Steve ( talk) 18:06, 9 August 2011 (UTC)
The merge seems to have failed and I have detagged both articles.- Sheer Incompetence ( talk) Now with added dubiosity! 22:45, 28 September 2011 (UTC)
In the Tensor Generalization, in the areas where Einstein's summation is presented, shouldn't there be a sigma there? I mean, reading it just like that would just be unclear - if you say that Ji=oijEj, one might think that for any j, J3=o3j*Ej is correct. I'm not a wiki expert, just went through the article and noticed that, and I thought why not write it here. the same thing goes right below it, with the resistivity. — Preceding unsigned comment added by 132.70.170.23 ( talk) 16:05, 10 October 2011 (UTC)
Here the introduction of the tensor form is mixed with introduction of inhomogeneous material. However the tensor form and inhomogeneous material are two separate steps of generalization. It would be probably easier to understand to make these two steps separate: first by allowing an inhomogeneous material by using local definition as it is already done using E and j. Its just allowing E and j to be a field instead of global values. The introduction of the tensor can then be done without reference to a position. -- Ulrich67 ( talk) 00:13, 20 December 2011 (UTC)
These numbers are confusing. One could use the scale of copper, writing the conducitivty in percentages of copper, which is the second most doncuting pure metal and is very common. This is an accepted scale I think, called the IACS. — Preceding unsigned comment added by 31.210.186.117 ( talk) 08:42, 20 April 2012 (UTC)
In the section Resistance versus resistivity in complicated geometries, shouldn't it be Gauss's law
for the electric field E rather than Poisson's equation
for the electric potential V? It seems slightly incoherent... F = q(E+v×B) ⇄ ∑ici 18:55, 6 May 2012 (UTC)
This section is unreferenced. Pasting in what was the text there (edited now) showed that many sites are taking this unreferenced page as their reference, but revealed no good references for the claims.
Someone familiar with how electron's path through a conductor is impeded in such a way as to give rise to resistance should look at this section, and add references.
Well, there is no understanding of this displayed here at all. Maybe there is a good physicist who could spend a bit of time putting in an explanation. — Preceding
unsigned comment added by
82.69.66.91 (
talk)
22:59, 15 June 2012 (UTC)
I noticed that the table of resistivities and conductivities seems to be sorted by increasing/decreasing resistivity, but there are several that are out of order. I'm not sure if this is just people adding stuff, or if they're trying to keep the carbons/waters together, but I think it would be most helpful if it was sorted properly. I plan to do some work on it when I get some free time. ~ Adjwilley ( talk) 21:23, 15 June 2012 (UTC)
The article does not clearly explain what an ohm metre is. Ayrton and Mather (1911) state: "The specific resistance or resistivity of a material is usually expressed as the resistance in microhms...of a centimetre cube or of an inch cube". Using the MKS system, the equivalent would be the resistance of a metre cube. Is this correct? Biscuittin ( talk) 07:26, 18 October 2012 (UTC)
If ohm metre is an abbreviation for ohm metres per square metre then why doesn't it say so in the lead section? The lead section is completely unreferenced and I also question the statement "Electrical resistivity (also known as resistivity, specific electrical resistance...). Surely specific electrical resistance is simply a ratio (based on Silver = 1) and has no units? Because of these questions, I have added an "accuracy" tag. Biscuittin ( talk) 18:04, 19 October 2012 (UTC)
Name of metal | Centimetre cube † | Inch cube † | Relative resistance |
---|---|---|---|
Silver | 1.48 | 0.583 | 1 |
Copper | 1.55 | 0.610 | 1.04 |
Aluminium | 2.43 | 0.96 | 1.64 |
Iron | 9.7 | 3.82 | 6.56 |
† Resistance in international microhms at 0°C
What is your source for the statement "ohm square-metres per metre is the same thing as ohm metres"? Biscuittin ( talk) 22:07, 19 October 2012 (UTC)
Metre is an SI base unit and ohm and siemens are SI derived units. Ohm metre and siemens per metre appear to be derived derived units so I question whether they are SI units at all. See [4] [5] Biscuittin ( talk) 18:39, 22 October 2012 (UTC)
What is the objection to having an explanation (for non-technical readers) of the term ohm metre in the lead section of the article? Biscuittin ( talk) 18:35, 23 October 2012 (UTC)
The resistivity listed in the table for Teflon seems too high (therefore, too small of a conductivity). From other sources, it appears that the bulk DC conductivity of Teflon should be somewhere between 10^-15 and 10^-18 [S/m]. — Preceding unsigned comment added by 129.7.16.24 ( talk) 01:10, 22 November 2012 (UTC)
Wikipedia:Naming conventions#Titles containing "and" — Preceding unsigned comment added by 24.131.80.19 ( talk) 00:03, 20 November 2012 (UTC)
The table listing resistivity and conductivity of various material needs correction. Since resistivity and conductivity should be reciprocals, the table cannot be correct. Two examples: 1. Assuming the resistivity for GaAs is correct at 5 x 10^-7 to 10 x 10^-3 (that should actually read 1 x 10^-2)... the conductivity for GaAs should be 1 x 10^2 to 2 x 10^6 . 2. Assuming the resistivity of Carbon (diamond) is correct at 1 x 10^-12 .... The conductivity for Carbon (diamond) should be 1 x 10^12. . There should be no wiggle room for variations as the units are simply reciprocals... nothing novel is introduced so there should be no variation. 1/2 dozen is always 6 never ~7 — Preceding unsigned comment added by 70.171.44.124 ( talk) 16:08, 16 October 2013 (UTC)
Hello!
My friend was disappointed that he could not find here the Nernst-Einstein law (and used it to tell me that Wiki is not that great). This law is described on the French article, at the very end. Would it make sense to add this here?
Thank you for any insight on this!
Meumeumarj ( talk) 16:25, 1 March 2014 (UTC) // Talk on my French page
I was reading in a forum
"Remember that it isn't a matter of electrons moving from one end of the wire to another;
instead, the electromagnetic field moves through the wire, making electrons jump from one
atom to the next, and then another electron from that atom to the next, in a wave."
This seems more in line with the Band theory simplified given in the previous paragraph. — Preceding unsigned comment added by 95.237.142.70 ( talk) 09:03, 20 August 2014 (UTC)
This page is an archive of past discussions. Do not edit the contents of this page. If you wish to start a new discussion or revive an old one, please do so on the current talk page. |
After searching other locations, I'm finding very different versions of resistivity for Al. Something closer to 2.6 or 2.8 rather than 2.282... -- Hobit 14:19, 11 October 2005 (UTC)
The table of resistivity values looks exactly like the one in my physics textbook (Physics for Scientists and Engineers, with Modern Physics by Serway and Jewett). Is there a missing citation here or am I missing something? Mahsmanj
Material | Resistivity (ohm metres) | Temperature coefficient per kelvin |
---|---|---|
Chromium | 1.8 × 10-7 | .0000059 |
Tin | 1.15 × 10-5 | .0042 |
Silver, German | 3.3 × 10-5 | .0004 |
Seawater | 2.0 × 10-1 [1] | ? |
Pure water | 2.5 × 105 | ? |
Human skin | approximately 5.0 × 105 | ? |
German silver is also known as nickel silver. If you look for the resistivity nickel silver instead of german silver, you will have better luck finding a source. -Rudy
Does anybody know how resistivity relates to the volume of an object? That is, if I had something that looked more like a sphere than a thin wire, and wanted to calculate its resistance using its resistivity, how would I do it?
It probably involves integrals, though I don't know if the equations are straightforward. Remember that this isn't a straight volume or surface area type calculation. You're calculating the resistance of the object, but the resistance will be different for the same object depending on how the electrodes are arranged. Would you have to calculate the current flow through each differential cross section of the entire object? This gets into bulk resistance calculations that I am not familiar with (but would like to be). — Omegatron 19:00, 24 February 2007 (UTC)
19:59, 2 July 2007 (UTC)19:59, 2 July 2007 (UTC) 155.104.37.17 19:59, 2 July 2007 (UTC) Sorry to add here, but I'm not seeing any better way to add a comment to the page.
Resistivity may also change under many conditions besides temperature. Humidity, for instance, as a material absorbs water, or even in a vacuum, where it outgasses whatever material. This is an effect we have seen before - nylon is a good example, it's resistivity goes up under a vacuum.
I think it would be better if we combined the tables of resistivity and conductivity since they are so fundamentally linked. Please discuss this at Talk:Electrical conductivity. Fresheneesz 22:52, 27 May 2006 (UTC)
somebody has just defaced the general equation: it should be rho=R multiplied by A divided by length
I have changed it twice but someone keeps changing it back. It should be
and not
I do not make out that I understand everything that is involved with resistivity as I am only a year 11 pupil studying it for my GCSE but about this I am quite certain and I have also verified it with my teacher. Some one told me to check this up on an External sitewhich I did. There equation of
which can be rearranged to form
If anyone can explain why it should be the other way please try. Mrpowers999 16:16, 24 February 2007 (UTC)
which can be rearranged to form
which can be rearranged to form
Nov 27, 2007 I corrected the units for resistivity from Ohm-meters to Ohms per meter. —Preceding unsigned comment added by 206.104.31.54 ( talk) 01:24, 29 November 2007 (UTC)
NB: In the UK, Year 11 is the final year of compulsary education. Mrpowers999 will be either 15 or 16, NOT 11. This is because school starts at 4 or 5 (not birth) and the first school year is called reception. Anonymous —Preceding unsigned comment added by 79.71.27.222 ( talk) 18:23, 23 November 2008 (UTC)
I think either the table is wrong, or the values in the Silver, Copper and Gold articles are wrong. Also, considering that the resistivity is given with much less precision than the coefficient, it seems misleading to add 1.47... to ~.0038... and get ~1.4738.... Κσυπ Cyp 13:06, 23 April 2007 (UTC)
I get 2.45 for Al, 1.56 for Cu, 1.5 for Ag, 2.04 for Au, 4.9 for W, 8.9 for Fe, 9.8 for Pt, 19 for Pb (all 10^-8), supposedly for "commercially pure" samples between 288-298K. Revised Nuffield Advanced Science Book of Data, Addison Wesley Longman Limited. Presumably it varies greatly between samples. ⇌ Elektron 02:58, 1 September 2007 (UTC)
I don't dispute any of the values/coefficients in the table, but there is an error in the note: "*The numbers in this column increase or decrease the significand portion of the resistivity. For example, at 21°C (294.15 K), the resistivity of silver is 1.65×10^−8." Either this conductivity change was calculated for a 10°C (not 1°C) temp. change and the note should reflect such, or the coefficient used in the calculation was .038 instead of the proper value of .0038. Also, I think the simple relation Δρ = α ΔT ρ where α is the coef. is more clear than the phrase about the significand portion. Clcasto ( talk) 18:19, 3 January 2008 (UTC)
And why is this table not incorporated?: http://en.wikipedia.org/wiki/Electrical_resistivities_of_the_elements_(data_page) It seems to provide a full chart of all resistivities of all chemical elements... Seems pretty fundamental in any resistivity chart, don't you think? ;) —Preceding unsigned comment added by 62.131.171.23 ( talk) 21:04, 18 February 2008 (UTC)
Plus very suspicious value for calcium. As far I had deal with the calcite mollusc houses, calcite containing walls, calcite stone, cement, silicate brics etc calcium much containing materials them all are roughly good isolators. I suggess may be an author had criscrossed value 3E-8 with 3E+8???? Or value is given for naturally flooded carbonites deep under soil, thus the water is that agent making so strange resistance??? —Preceding unsigned comment added by 85.254.232.1 ( talk) 15:43, 30 March 2009 (UTC)
I updated the table for conductivity by simple calculation from the already present resistivity (no other change was made) EV1Te ( talk) 08:25, 28 April 2011 (UTC)
I'm sure the table is still wrong. Conductivity multiplied by resistivity is always 1. Eddietoran ( talk) 20:37, 22 August 2011 (UTC)
The temperature coefficient of resistivity for copper is 0.0039 everywhere but this page, where it is 0.0068. — Preceding unsigned comment added by Zxw 095 ( talk • contribs) 21:35, 29 March 2013 (UTC)
well, 1.56 for copper is quite good, I don't know how the guy did it, but around room temperature (18-21°C), bulk copper of high purity (99.9999% Cu) is supposed to be around 1.7-1.8 depending on the guy doing the experiment. so you'll understand that 1.56 renders me a bit suspicious of the whole book. for a scientifical / engineering point of view, 5% variation in resistivity may be very important, and 0.1% thermical variations are important as 100°C of heat during use is not unheard of, meaning that 0.1% or 0.2% per°C means either +10% or +20% resistivity, with may change all behaviours if you need precise input/output.
I had another information to add to the resistivity article, but I don't really have the time and the know-how to put it in the main article :
basically, resistivity is intrinseque to a material, depending on its atome (atomic properties such as masse, active surface...etc) then you add modifiers :
currently the size of both grains and sample really have impact on resistivity when the dimensions approche or are under the micrometer range, but maybe the fact should be mentionned, as well as impurity effects.
here are some articles (list is non exaustive)on what I'm saying (as I work mostly in mircoelectronics, those works deal with that subject, but more general links can maybe be found, I have some thesis reports, but mostly in french):
If someone wants to inclued those informations in this page, and can't find the information or want to discuss it, write in my user page, I will connect to it a bit in the near futur. Calavente ( talk) 01:22, 23 January 2008 (UTC)
Hey, in spanish wikipedia...
Material | Resistividad (en 20°C-25ºC) (Ω·m) |
---|---|
Plata [1] | 1.55 x 10-8 |
Cobre [2] | 1.70 x 10-8 |
Oro [3] | 2.22 x 10-8 |
Aluminio [4] | 2.82 x 10-8 |
Wolframio [5] | 5.65 x 10-8 |
Níquel [6] | 6.40 x 10-8 |
Hierro [7] | 8.90 x 10-8 |
Platino [8] | 10.60 x 10-8 |
Estaño [9] | 11.50 x 10-8 |
Acero inoxidable 301 [10] | 72.00 x 10-8 |
Grafito [11] | 60.00 x 10-8 |
Based on Matweb that I consider, good, for the resistivity article, we can be more accuracy in another dedicated only to the values.— Nicoguaro ( talk) 14:26, 1 April 2008 (UTC)
References
Is there anyway to get the table to meaningfully sort on resistivity? The current sort doesn't seem to grok scientific notation... -- Belg4mit ( talk) 01:54, 11 September 2008 (UTC)
Resistance and Resistivity for Selected Common Metals [2] 10-ga wire Resistance Ohms/ft Resistivity (10-6 ohm-cm) Silver 0.000944 1.629 Copper 0.000999 1.724 Gold 0.00114 2.44 Aluminum 0.00164 2.828 Iridium 0.00306 5.29 Brass 0.00406 7.00 Nickel 0.00452 7.8 Iron 0.00579 10.0 Platinum 0.00579 10.0 Steel 0.00684 11.8 Lead 0.0127 22
This article would be more useful to the general reader if more practical data like above were added. - 71.174.184.42 ( talk) 00:07, 21 May 2009 (UTC)
I checked the reference for copper that is listed in the table and the two numbers do not match. We should not list a reference with a different value, or even better we should list the correct value and a reference that verifies it. —Preceding unsigned comment added by 71.33.199.247 ( talk) 21:19, 26 March 2010 (UTC)
The "sort" option in tables doesn't seem to sort numbers, but instead sorts as strings - this makes it useless if using scientific notation or any number format that doesn't sort the same as strings. The "sort" function needs a stronger parser that can be told "These are numbers, not strings" and sort by magnitude of the number, not just as a string sort. -- Wtshymanski ( talk) 19:44, 10 February 2011 (UTC)
These edits [ [3]] seem to largely consist of changing the units or resistivity from Ωm to m/S and changing numerical notation from e.g. 58×106 to 58∘106. The use of m/S while technically correct is virtually unheard of (at least unheard of by Google). The dot-notation for simple arithmetic multiplication is also correct, but probably less common the than the cross. These edits are clearly made in good faith, but they are very extensive; is there anything good that in them that can be saved, or should they just be reverted completely? -- catslash ( talk) 11:16, 21 May 2011 (UTC)
In the table concerning conductivity and density, I feel like the product of the two parameters (what is given) is not as interesting as the quotient. A designer would be interested in conductivity per unit of mass, so you'd want resistivity/density. A high value would mean lots of conduction for a given mass. I think the given values, while correct, are not useful. — Preceding unsigned comment added by 128.196.211.58 ( talk) 22:43, 5 August 2011 (UTC)
some are in scientific notation (1.0x10^14), while some aren't (10x10^14). I do not know whether these were typed with the decimal forgotten, or if it's a different notation intentionally. Maybe someone could track down the poster? — Preceding unsigned comment added by 67.42.71.64 ( talk) 19:49, 9 June 2014 (UTC)
The entire left side of the table lists values in a strange format, viz.
Which I take to mean
... The whole table needs to be revised to reflect ordinary notation, as I wouldn't want anyone thinking we are using Euler's number here. I like to saw logs! ( talk) 06:12, 9 August 2011 (UTC)
Wtshymanski proposes a merge. We can discuss it here. -- Steve ( talk) 18:06, 9 August 2011 (UTC)
The merge seems to have failed and I have detagged both articles.- Sheer Incompetence ( talk) Now with added dubiosity! 22:45, 28 September 2011 (UTC)
In the Tensor Generalization, in the areas where Einstein's summation is presented, shouldn't there be a sigma there? I mean, reading it just like that would just be unclear - if you say that Ji=oijEj, one might think that for any j, J3=o3j*Ej is correct. I'm not a wiki expert, just went through the article and noticed that, and I thought why not write it here. the same thing goes right below it, with the resistivity. — Preceding unsigned comment added by 132.70.170.23 ( talk) 16:05, 10 October 2011 (UTC)
Here the introduction of the tensor form is mixed with introduction of inhomogeneous material. However the tensor form and inhomogeneous material are two separate steps of generalization. It would be probably easier to understand to make these two steps separate: first by allowing an inhomogeneous material by using local definition as it is already done using E and j. Its just allowing E and j to be a field instead of global values. The introduction of the tensor can then be done without reference to a position. -- Ulrich67 ( talk) 00:13, 20 December 2011 (UTC)
These numbers are confusing. One could use the scale of copper, writing the conducitivty in percentages of copper, which is the second most doncuting pure metal and is very common. This is an accepted scale I think, called the IACS. — Preceding unsigned comment added by 31.210.186.117 ( talk) 08:42, 20 April 2012 (UTC)
In the section Resistance versus resistivity in complicated geometries, shouldn't it be Gauss's law
for the electric field E rather than Poisson's equation
for the electric potential V? It seems slightly incoherent... F = q(E+v×B) ⇄ ∑ici 18:55, 6 May 2012 (UTC)
This section is unreferenced. Pasting in what was the text there (edited now) showed that many sites are taking this unreferenced page as their reference, but revealed no good references for the claims.
Someone familiar with how electron's path through a conductor is impeded in such a way as to give rise to resistance should look at this section, and add references.
Well, there is no understanding of this displayed here at all. Maybe there is a good physicist who could spend a bit of time putting in an explanation. — Preceding
unsigned comment added by
82.69.66.91 (
talk)
22:59, 15 June 2012 (UTC)
I noticed that the table of resistivities and conductivities seems to be sorted by increasing/decreasing resistivity, but there are several that are out of order. I'm not sure if this is just people adding stuff, or if they're trying to keep the carbons/waters together, but I think it would be most helpful if it was sorted properly. I plan to do some work on it when I get some free time. ~ Adjwilley ( talk) 21:23, 15 June 2012 (UTC)
The article does not clearly explain what an ohm metre is. Ayrton and Mather (1911) state: "The specific resistance or resistivity of a material is usually expressed as the resistance in microhms...of a centimetre cube or of an inch cube". Using the MKS system, the equivalent would be the resistance of a metre cube. Is this correct? Biscuittin ( talk) 07:26, 18 October 2012 (UTC)
If ohm metre is an abbreviation for ohm metres per square metre then why doesn't it say so in the lead section? The lead section is completely unreferenced and I also question the statement "Electrical resistivity (also known as resistivity, specific electrical resistance...). Surely specific electrical resistance is simply a ratio (based on Silver = 1) and has no units? Because of these questions, I have added an "accuracy" tag. Biscuittin ( talk) 18:04, 19 October 2012 (UTC)
Name of metal | Centimetre cube † | Inch cube † | Relative resistance |
---|---|---|---|
Silver | 1.48 | 0.583 | 1 |
Copper | 1.55 | 0.610 | 1.04 |
Aluminium | 2.43 | 0.96 | 1.64 |
Iron | 9.7 | 3.82 | 6.56 |
† Resistance in international microhms at 0°C
What is your source for the statement "ohm square-metres per metre is the same thing as ohm metres"? Biscuittin ( talk) 22:07, 19 October 2012 (UTC)
Metre is an SI base unit and ohm and siemens are SI derived units. Ohm metre and siemens per metre appear to be derived derived units so I question whether they are SI units at all. See [4] [5] Biscuittin ( talk) 18:39, 22 October 2012 (UTC)
What is the objection to having an explanation (for non-technical readers) of the term ohm metre in the lead section of the article? Biscuittin ( talk) 18:35, 23 October 2012 (UTC)
The resistivity listed in the table for Teflon seems too high (therefore, too small of a conductivity). From other sources, it appears that the bulk DC conductivity of Teflon should be somewhere between 10^-15 and 10^-18 [S/m]. — Preceding unsigned comment added by 129.7.16.24 ( talk) 01:10, 22 November 2012 (UTC)
Wikipedia:Naming conventions#Titles containing "and" — Preceding unsigned comment added by 24.131.80.19 ( talk) 00:03, 20 November 2012 (UTC)
The table listing resistivity and conductivity of various material needs correction. Since resistivity and conductivity should be reciprocals, the table cannot be correct. Two examples: 1. Assuming the resistivity for GaAs is correct at 5 x 10^-7 to 10 x 10^-3 (that should actually read 1 x 10^-2)... the conductivity for GaAs should be 1 x 10^2 to 2 x 10^6 . 2. Assuming the resistivity of Carbon (diamond) is correct at 1 x 10^-12 .... The conductivity for Carbon (diamond) should be 1 x 10^12. . There should be no wiggle room for variations as the units are simply reciprocals... nothing novel is introduced so there should be no variation. 1/2 dozen is always 6 never ~7 — Preceding unsigned comment added by 70.171.44.124 ( talk) 16:08, 16 October 2013 (UTC)
Hello!
My friend was disappointed that he could not find here the Nernst-Einstein law (and used it to tell me that Wiki is not that great). This law is described on the French article, at the very end. Would it make sense to add this here?
Thank you for any insight on this!
Meumeumarj ( talk) 16:25, 1 March 2014 (UTC) // Talk on my French page
I was reading in a forum
"Remember that it isn't a matter of electrons moving from one end of the wire to another;
instead, the electromagnetic field moves through the wire, making electrons jump from one
atom to the next, and then another electron from that atom to the next, in a wave."
This seems more in line with the Band theory simplified given in the previous paragraph. — Preceding unsigned comment added by 95.237.142.70 ( talk) 09:03, 20 August 2014 (UTC)