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|[[Grafen]] || 1,00 x 10<sup>−8</sup>|| 1,00 x 10<sup>8</sup> ||−0,000 2||<ref name="UMDnews">[https://newsdesk.umd.edu/scitech/release.cfm?ArticleID=1621 Physicists Show Electrons Can Travel More Than 100 Times Faster in Graphene], [https://web.archive.org/web/20130919083015/https://newsdesk.umd.edu/scitech/release.cfm?ArticleID=1621 date=September 19, 2013]. Newsdesk.umd.edu (2008-03-24). Retrieved on 2014-02-03.</ref>
|[[Grafen]] || 1,00 x 10<sup>−8</sup>|| 1,00 x 10<sup>8</sup> ||−0,000 2||<ref name="UMDnews">[https://newsdesk.umd.edu/scitech/release.cfm?ArticleID=1621 Physicists Show Electrons Can Travel More Than 100 Times Faster in Graphene], [https://web.archive.org/web/20130919083015/https://newsdesk.umd.edu/scitech/release.cfm?ArticleID=1621 date=September 19, 2013]. Newsdesk.umd.edu (2008-03-24). Retrieved on 2014-02-03.</ref>
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|[[Srebro]]|| 1,59  x 10<sup>−8</sup> || 6,3  x 10<sup>7</sup> ||0,003 8|| <ref name="serway">{{cite book | author=Raymond A. Serway | title=Principles of Physics | edition=2nd| year=1998 | publisher=Saunders College Pub | location=Fort Worth, Texas; London | isbn=0-03-020457-7 | page=602}}</ref><ref name="Griffiths">{{cite book|title=Introduction to Electrodynamics|publisher=Prentice Hal]|year=1999|isbn=0-13-805326-X|edition=3rd|location=Upper Saddle River, New Jersey|page=286|chapter=7. Electrodynamics|oclc=40251748|author=David Griffiths|editor=Alison Reeves|origyear=1981}}<!--| accessdate = 2006-01-29 --></ref>
|[[Srebro]]|| 1,59  x 10<sup>−8</sup> || 6,3  x 10<sup>7</sup> ||0,003 8|| <ref name="serway">{{Citiranje knjige | author=Raymond A. Serway | title=Principles of Physics | edition=2nd| year=1998 | publisher=Saunders College Pub | location=Fort Worth, Texas; London | isbn=0-03-020457-7 | page=602}}</ref><ref name="Griffiths">{{Citiranje knjige|title=Introduction to Electrodynamics|publisher=Prentice Hal]|year=1999|isbn=0-13-805326-X|edition=3rd|location=Upper Saddle River, New Jersey|page=286|chapter=7. Electrodynamics|oclc=40251748|author=David Griffiths|editor=Alison Reeves|origyear=1981}}<!--| accessdate = 2006-01-29 --></ref>
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|[[Bakar (element)|Bakar]]|| 1,68 x 10<sup>−8</sup> || 5,96 x 10<sup>7</sup> || 0,003 862 || <ref name="Giancoli">{{cite book|title=Physics for Scientists and Engineers with Modern Physics|publisher=Prentice Hall|year=2009|isbn=0-13-149508-9|edition=4th|location=Upper Saddle River, New Jersey|page=658|chapter=25. Electric Currents and Resistance|author=Douglas Giancoli|editor=Jocelyn Phillips|origyear=1984}}<!--| accessdate = 2013-03-04 --></ref>
|[[Bakar (element)|Bakar]]|| 1,68 x 10<sup>−8</sup> || 5,96 x 10<sup>7</sup> || 0,003 862 || <ref name="Giancoli">{{Citiranje knjige|title=Physics for Scientists and Engineers with Modern Physics|publisher=Prentice Hall|year=2009|isbn=0-13-149508-9|edition=4th|location=Upper Saddle River, New Jersey|page=658|chapter=25. Electric Currents and Resistance|author=Douglas Giancoli|editor=Jocelyn Phillips|origyear=1984}}<!--| accessdate = 2013-03-04 --></ref>
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|[[Žarenje|Žareni]] [[Bakar (element)|bakar]] || 1,72 x 10<sup>−8</sup> || 5,8 x 10<sup>7</sup> || 0,003 93 ||<ref>[https://archive.org/details/copperwiretables31unituoft Copper wire tables : United States. National Bureau of Standards : Free Download & Streaming : Internet Archive]. Archive.org (2001-03-10). Retrieved on 2014-02-03.</ref>
|[[Žarenje|Žareni]] [[Bakar (element)|bakar]] || 1,72 x 10<sup>−8</sup> || 5,8 x 10<sup>7</sup> || 0,003 93 ||<ref>[https://archive.org/details/copperwiretables31unituoft Copper wire tables : United States. National Bureau of Standards : Free Download & Streaming : Internet Archive]. Archive.org (2001-03-10). Retrieved on 2014-02-03.</ref>
Redak 65: Redak 65:
| Električni čelik <br /> s usmjerenim zrnom || 4,60 x 10<sup>−7</sup> || 2,17 x 10<sup>6</sup> ||||<ref>{{cite web|url=http://www.jfe-steel.co.jp/en/products/electrical/catalog/f1e-001.pdf |title=JFE steel |format=PDF |accessdate=2012-10-20}}</ref>
| Električni čelik <br /> s usmjerenim zrnom || 4,60 x 10<sup>−7</sup> || 2,17 x 10<sup>6</sup> ||||<ref>{{cite web|url=http://www.jfe-steel.co.jp/en/products/electrical/catalog/f1e-001.pdf |title=JFE steel |format=PDF |accessdate=2012-10-20}}</ref>
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| Manganin || 4,82 x 10<sup>−7</sup> || 2,07 x 10<sup>6</sup> || 0,000 002 ||<ref name="giancoli">{{cite book | author=Douglas C. Giancoli | title=Physics: Principles with Applications | edition=4th | year=1995 | publisher=Prentice Hall | location=London | isbn=0-13-102153-2}}<br>(see also [http://hyperphysics.phy-astr.gsu.edu/hbase/Tables/rstiv.html Table of Resistivity]. hyperphysics.phy-astr.gsu.edu)
| Manganin || 4,82 x 10<sup>−7</sup> || 2,07 x 10<sup>6</sup> || 0,000 002 ||<ref name="giancoli">{{Citiranje knjige | author=Douglas C. Giancoli | title=Physics: Principles with Applications | edition=4th | year=1995 | publisher=Prentice Hall | location=London | isbn=0-13-102153-2}}<br>(see also [http://hyperphysics.phy-astr.gsu.edu/hbase/Tables/rstiv.html Table of Resistivity]. hyperphysics.phy-astr.gsu.edu)
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Redak 76: Redak 76:
| Kromnikal || 1,10 x 10<sup>−6</sup> || 6,7 x 10<sup>5</sup> || 0,000 4 || <ref name="serway"/>
| Kromnikal || 1,10 x 10<sup>−6</sup> || 6,7 x 10<sup>5</sup> || 0,000 4 || <ref name="serway"/>
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| GaAs || od 1,00 x 10<sup>−3</sup> do 1,00 x 10<sup>8</sup> || od 1,00 x 10<sup>−8</sup> do 10<sup>3</sup> || ||<ref name="Ohring">{{cite book | author = Milton Ohring | title = Engineering materials science, Volume 1| edition = 3rd | year = 1995 | page = 561|isbn=0125249950|publisher=Academic Press}}</ref>
| GaAs || od 1,00 x 10<sup>−3</sup> do 1,00 x 10<sup>8</sup> || od 1,00 x 10<sup>−8</sup> do 10<sup>3</sup> || ||<ref name="Ohring">{{Citiranje knjige | author = Milton Ohring | title = Engineering materials science, Volume 1| edition = 3rd | year = 1995 | page = 561|isbn=0125249950|publisher=Academic Press}}</ref>
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|[[Ugljik]] ([[Amorfna tvar|amorfni]])|| od 5,00 x 10<sup>−4</sup> do 8,00 x 10<sup>−4</sup> || od 1,25 x 10<sup>3</sup> do 2 x 10<sup>3</sup> || −0.0005||<ref name="serway"/><ref>Y. Pauleau, Péter B. Barna, P. B. Barna (1997) ''Protective coatings and thin films: synthesis, characterization, and applications'', p. 215, Springer, {{ISBN|0-7923-4380-8}}.</ref>
|[[Ugljik]] ([[Amorfna tvar|amorfni]])|| od 5,00 x 10<sup>−4</sup> do 8,00 x 10<sup>−4</sup> || od 1,25 x 10<sup>3</sup> do 2 x 10<sup>3</sup> || −0.0005||<ref name="serway"/><ref>Y. Pauleau, Péter B. Barna, P. B. Barna (1997) ''Protective coatings and thin films: synthesis, characterization, and applications'', p. 215, Springer, {{ISBN|0-7923-4380-8}}.</ref>

Inačica od 23:41, 16. studenoga 2021.

Električna otpornost jest električni otpor žice presjeka 1 mm2 i duljine 1 m.

Električna otpornost (oznaka ρ), zastarjeli naziv specifični električni otpor, fizikalna je veličina koja opisuje svojstvo tvari da se opire protjecanju električne struje. Električna otpornost recipročna je električnoj provodnosti. Može se odrediti mjerenjem električnoga otpora R, duljine električnog vodiča u smjeru električne struje l i ploštine njegova poprečnog presjeka S, to jest:

[math]\displaystyle{ \rho = \frac{R \cdot S}{l} }[/math]

Mjerna jedinica električne otpornosti je ommetar (Ωm).

Najmanju električnu otpornost imaju supravodiči, potom električni vodiči, poluvodiči i elektroliti, a najveću električni izolatori. Osim o vrsti tvari otpornost ovisi i o primjesama u tvari, temperaturi, strukturi tvari, tako na primjer otpornost vode u tekućem stanju jako ovisi o koncentraciji otopljenih soli (ukupne otopljene tvari).[1]

Električna provodnost

Električna provodnost (oznaka σ), zastarjeli naziv specifična električna vodljivost, fizikalna je veličina koja opisuje svojstvo tvari da provodi električnu struju. Električna provodnost recipročna je električnoj otpornosti. Može se odrediti mjerenjem električne vodljivosti G, duljine električnog vodiča u smjeru električne struje l i ploštine njegova poprečnog presjeka S, to jest:

[math]\displaystyle{ \sigma = \frac{G \cdot l}{S} }[/math]

Mjerna jedinica električne provodnosti je simens po metru (S/m).

Najveću električnu provodnost imaju supravodiči, potom električni vodiči, poluvodiči i elektroliti, a najmanju električni izolatori. Osim o vrsti tvari provodnost ovisi i o primjesama u tvari, temperaturi, strukturi tvari, na primjer provodnost vode u tekućem stanju jako ovisi o koncentraciji otopljenih soli (ukupne otopljene tvari).[2]

Električna otpornost i provodnost nekih tvari

Lista ispod pokazuje električnu otpornost, električnu provodnost i temperaturni koeficijent električnog otpora za različite materijale na 20 °C (293 K):

Materijal ρ (Ω·m) kod 20 °C σ (S/m) kod 20 °C Temperaturni koeficijent
električnog otpora
(K−1) 		Izvori
Grafen 1,00 x 10−8 1,00 x 108 −0,000 2 [3]
Srebro 1,59 x 10−8 6,3 x 107 0,003 8 [4][5]
Bakar 1,68 x 10−8 5,96 x 107 0,003 862 [6]
Žareni bakar 1,72 x 10−8 5,8 x 107 0,003 93 [7]
Zlato 2,44 x 10−8 4,11 x 107 0,003 4 [4]
Aluminij 2,82 x 10−8 3,5 x 107 0,003 9 [4]
Kalcij 3,36 x 10−8 2,98 x 107 0,004 1
Volfram 5,60 x 10−8 1,79 x 107 0,004 5 [4]
Cink 5,90 x 10−8 1,69 x 107 0,003 7 [8]
Nikal 6,99 x 10−8 1,43 x 107 0,006
Litij 9,28 x 10−8 1,08 x 107 0,006
Željezo 9,71 x 10−8 1,00 x 107 0,005 [4]
Platina 1,06 x 10−7 9,43 x 106 0,003 92 [4]
Kositar 1,09 x 10−7 9,17 x 106 0,004 5
Ugljični čelik (1010) 1,43 x 10−7 6,99 x 106 [9]
Olovo 2,20 x 10−7 4,55 x 106 0,003 9 [4]
Titanij 4,20 x 10−7 2,38 x 106 0,003 8
Električni čelik
s usmjerenim zrnom		 4,60 x 10−7 2,17 x 106 [10]
Manganin 4,82 x 10−7 2,07 x 106 0,000 002 [11]
Konstantan 4,90 x 10−7 2,04 x 106 0,000 008 [12]
Nehrđajući čelik (18/8 CrNi) 6,90 x 10−7 1,45 x 106 0,000 94 [13]
Živa 9,80 x 10−7 1,02 x 106 0,000 9 [11]
Kromnikal 1,10 x 10−6 6,7 x 105 0,000 4 [4]
GaAs od 1,00 x 10−3 do 1,00 x 108 od 1,00 x 10−8 do 103 [14]
Ugljik (amorfni) od 5,00 x 10−4 do 8,00 x 10−4 od 1,25 x 103 do 2 x 103 −0.0005 [4][15]
Ugljik (grafit) od 2.50 x 10−6 do 5.00x 10−6 od 2,00 x 105 do 3,00 x 103 [16]
Germanij 0,46 2,17 − 0,048 [4][5]
Morska voda 0,20 4,80 [17]
Bazenska voda od 0,333 do 0,40 od 0,25 do 0,30 [18]
Pitka voda od 20 do 2 000 od 5,00 x 10−4 do 5,00 x 10−2
Silicij 6.40 x 102 1,56 x 10−3 -0,075 [4]
Drvo od 1.00 x 103 do 1,00 x 104 od 10−4 do 0−3 [19]
Destilirana voda 1,80 x 105 5,50 x 10−6 [20]
Staklo od 1,00 x 1011 do 1,00 x 1015 od 10−11 do 10−15 [4][5]
Tvrda guma 1,00 x 1013 10−14 [4]
Suho drvo od 1,00 x 1014 do 1,00 x 1016 od 10−16 do 10−14 [19]
Sumpor 1,00 x 1015 10−16 [4]
Zrak od 1,30 x 1014 do 3,30 x 1014 od 3 x 10−15 do 8 x 10−15 [21]
Dijamant 1,00 x 1012 10−13 [22]
Kremeno staklo 7,50 x 1017 1,30 x 10−18 [4]
PET 1,00 x 1021 10−21
Teflon od 1,00 x 1023 do 1,00 x 1025 od 10−25 do 10−23

Izvori

  1. ↑ električna otpornost, [1] "Hrvatska enciklopedija", Leksikografski zavod Miroslav Krleža, www.enciklopedija.hr, 2017.
  2. ↑ električna provodnost, [2] "Hrvatska enciklopedija", Leksikografski zavod Miroslav Krleža, www.enciklopedija.hr, 2017.
  3. ↑ Physicists Show Electrons Can Travel More Than 100 Times Faster in Graphene, date=September 19, 2013. Newsdesk.umd.edu (2008-03-24). Retrieved on 2014-02-03.
  4. ↑ 4,00 4,01 4,02 4,03 4,04 4,05 4,06 4,07 4,08 4,09 4,10 4,11 4,12 4,13 4,14 Raymond A. Serway (1998). Principles of Physics (2nd ed.). Fort Worth, Texas; London: Saunders College Pub. str. 602. ISBN 0-03-020457-7 
  5. ↑ 5,0 5,1 5,2 David Griffiths (1999) [1981]. "7. Electrodynamics". Unutar Alison Reeves. Introduction to Electrodynamics (3rd ed.). Upper Saddle River, New Jersey: Prentice Hal]. str. 286. ISBN 0-13-805326-X. OCLC 40251748 
  6. ↑ Douglas Giancoli (2009) [1984]. "25. Electric Currents and Resistance". Unutar Jocelyn Phillips. Physics for Scientists and Engineers with Modern Physics (4th ed.). Upper Saddle River, New Jersey: Prentice Hall. str. 658. ISBN 0-13-149508-9 
  7. ↑ Copper wire tables : United States. National Bureau of Standards : Free Download & Streaming : Internet Archive. Archive.org (2001-03-10). Retrieved on 2014-02-03.
  8. ↑ Physical constants. (PDF format; see page 2, table in the right lower corner). Retrieved on 2011-12-17.
  9. ↑ AISI 1010 Steel, cold drawn. Matweb
  10. ↑ "JFE steel" (PDF). http://www.jfe-steel.co.jp/en/products/electrical/catalog/f1e-001.pdf Pristupljeno 20. listopada 2012. 
  11. ↑ 11,0 11,1 Douglas C. Giancoli (1995). Physics: Principles with Applications (4th ed.). London: Prentice Hall. ISBN 0-13-102153-2 
    (see also Table of Resistivity. hyperphysics.phy-astr.gsu.edu)
  12. ↑ John O'Malley (1992) Schaum's outline of theory and problems of basic circuit analysis, p. 19, McGraw-Hill Professional, ISBN 0-07-047824-4
  13. ↑ Glenn Elert (ed.), "Resistivity of steel", The Physics Factbook, retrieved and archived 16 June 2011.
  14. ↑ Milton Ohring (1995). Engineering materials science, Volume 1 (3rd ed.). Academic Press. str. 561. ISBN 0125249950 
  15. ↑ Y. Pauleau, Péter B. Barna, P. B. Barna (1997) Protective coatings and thin films: synthesis, characterization, and applications, p. 215, Springer, ISBN 0-7923-4380-8.
  16. ↑ Hugh O. Pierson, Handbook of carbon, graphite, diamond, and fullerenes: properties, processing, and applications, p. 61, William Andrew, 1993 ISBN 0-8155-1339-9.
  17. ↑ Physical properties of sea water (Arhivirano 18. siječnja 2018.). Kayelaby.npl.co.uk. Retrieved on 2011-12-17.
  18. ↑ [3]. chemistry.stackexchange.com
  19. ↑ 19,0 19,1 Transmission Lines data. Transmission-line.net. Retrieved on 2014-02-03.
  20. ↑ R. M. Pashley; M. Rzechowicz; L. R. Pashley; M. J. Francis (2005). "De-Gassed Water is a Better Cleaning Agent". The Journal of Physical Chemistry B 109 (3): 1231–8. doi:10.1021/jp045975a. PMID 16851085 
  21. ↑ S. D. Pawar; P. Murugavel; D. M. Lal (2009). "Effect of relative humidity and sea level pressure on electrical conductivity of air over Indian Ocean". Journal of Geophysical Research 114: D02205. Bibcode 2009JGRD..11402205P. doi:10.1029/2007JD009716 
  22. ↑ Lawrence S. Pan, Don R. Kania, Diamond: electronic properties and applications, p. 140, Springer, 1994 ISBN 0-7923-9524-7.
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