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Izvor: Hrvatska internetska enciklopedija
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Redak 31: Redak 31:
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| 1.26 · 10<sup>0</sup>  
| 1.26 · 10<sup>0</sup>  
| 1 000 000 <ref>{{cite web|url=http://www.metglas.com/products/page5_1_2_6.htm |title="Metglas Magnetic Alloy 2714A", '&#39;Metglas'&#39; |publisher=Metglas.com |date= |accessdate=2011-11-08}}</ref>
| 1 000 000 <ref>{{Citiraj web|url=http://www.metglas.com/products/page5_1_2_6.htm |title="Metglas Magnetic Alloy 2714A", '&#39;Metglas'&#39; |publisher=Metglas.com |date= |accessdate=2011-11-08}}</ref>
| kod 0.5 [[Tesla|T]]
| kod 0.5 [[Tesla|T]]
| 100&nbsp;kHz
| 100&nbsp;kHz
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| 2.5 · 10<sup>-1</sup>
| 2.5 · 10<sup>-1</sup>
| 200 000 <ref name="Iron">{{cite web|url=http://hyperphysics.phy-astr.gsu.edu/hbase/tables/magprop.html#c2 |title="Magnetic Properties of Ferromagnetic Materials", '&#39;Iron'&#39; |publisher=C.R Nave Georgia State University |date= |accessdate=2013-12-01}}</ref>
| 200 000 <ref name="Iron">{{Citiraj web|url=http://hyperphysics.phy-astr.gsu.edu/hbase/tables/magprop.html#c2 |title="Magnetic Properties of Ferromagnetic Materials", '&#39;Iron'&#39; |publisher=C.R Nave Georgia State University |date= |accessdate=2013-12-01}}</ref>
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| 1.0 · 10<sup>-1</sup>
| 1.0 · 10<sup>-1</sup>
| 80 000 <ref name="Nanoperm">{{cite web|url=http://www.magnetec.de/eng/pdf/werkstoffkennlinien_nano_e.pdf |title="Typical material properties of NANOPERM", '&#39;Magnetec'&#39; |format=PDF |date= |accessdate=2011-11-08}}</ref>
| 80 000 <ref name="Nanoperm">{{Citiraj web|url=http://www.magnetec.de/eng/pdf/werkstoffkennlinien_nano_e.pdf |title="Typical material properties of NANOPERM", '&#39;Magnetec'&#39; |format=PDF |date= |accessdate=2011-11-08}}</ref>
| kod 0.5 T
| kod 0.5 T
| 10&nbsp;kHz
| 10&nbsp;kHz
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| 2.5 · 10<sup>-2</sup>
| 2.5 · 10<sup>-2</sup>
| 20 000 <ref name="hyper">{{cite web|url=http://hyperphysics.phy-astr.gsu.edu/hbase/solids/ferro.html |title="Relative Permeability", '&#39;Hyperphysics'&#39; |publisher=Hyperphysics.phy-astr.gsu.edu |date= |accessdate=2011-11-08}}</ref>
| 20 000 <ref name="hyper">{{Citiraj web|url=http://hyperphysics.phy-astr.gsu.edu/hbase/solids/ferro.html |title="Relative Permeability", '&#39;Hyperphysics'&#39; |publisher=Hyperphysics.phy-astr.gsu.edu |date= |accessdate=2011-11-08}}</ref>
| kod 0.002 T
| kod 0.002 T
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| 6.3 · 10<sup>-2</sup>
| 6.3 · 10<sup>-2</sup>
| 50 000 <ref name="nickal">{{cite web|url=http://www.nickel-alloys.net/nickelalloys.html |title=Nickel Alloys-Stainless Steels, Nickel Copper Alloys, Nickel Chromium Alloys, Low Expansion Alloys |publisher=Nickel-alloys.net |date= |accessdate=2011-11-08}}</ref>
| 50 000 <ref name="nickal">{{Citiraj web|url=http://www.nickel-alloys.net/nickelalloys.html |title=Nickel Alloys-Stainless Steels, Nickel Copper Alloys, Nickel Chromium Alloys, Low Expansion Alloys |publisher=Nickel-alloys.net |date= |accessdate=2011-11-08}}</ref>
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| 2.3 · 10<sup>-2</sup>
| 2.3 · 10<sup>-2</sup>
| 18 000 <ref name="vacuumschmeltze">{{cite web|url=http://www.vacuumschmelze.com/fileadmin/Medienbiliothek_2010/Downloads/HT/2013-03-27_Soft_Magnetic_Cobalt-_Iron_Alloys_final_version.pdf |title="Soft Magnetic Cobalt-Iron Alloys", '&#39;Vacuumschmeltze'&#39; |publisher=www.vacuumschmeltze.com |date= |accessdate=2013-08-03}}</ref>
| 18 000 <ref name="vacuumschmeltze">{{Citiraj web|url=http://www.vacuumschmelze.com/fileadmin/Medienbiliothek_2010/Downloads/HT/2013-03-27_Soft_Magnetic_Cobalt-_Iron_Alloys_final_version.pdf |title="Soft Magnetic Cobalt-Iron Alloys", '&#39;Vacuumschmeltze'&#39; |publisher=www.vacuumschmeltze.com |date= |accessdate=2013-08-03}}</ref>
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| 1.26 · 10<sup>-3</sup> - 2.26 · 10<sup>-3</sup>
| 1.26 · 10<sup>-3</sup> - 2.26 · 10<sup>-3</sup>
| 1 000 – 1 800<ref name="Carpenter">{{cite web|url=http://www.cartech.com/techarticles.aspx?id=1476|title=Magnetic Properties of Stainless Steels|author=Carpenter Technology Corporation|publisher=Carpenter Technology Corporation|year=2013}}</ref>
| 1 000 – 1 800<ref name="Carpenter">{{Citiraj web|url=http://www.cartech.com/techarticles.aspx?id=1476|title=Magnetic Properties of Stainless Steels|author=Carpenter Technology Corporation|publisher=Carpenter Technology Corporation|year=2013}}</ref>
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| 1.26 · 10<sup>-6</sup> - 8.8 · 10<sup>-6</sup>
| 1.26 · 10<sup>-6</sup> - 8.8 · 10<sup>-6</sup>
| 1.003–7 <ref name="SSAS">{{cite web|url=http://www.bssa.org.uk/cms/File/SSAS2.81-Magnetic%20Properties.pdf|title=Magnetic Properties of Stainless Steel|author=British Stainless Steel Association|publisher=Stainless Steel Advisory Service|year=2000}}</ref>  
| 1.003–7 <ref name="SSAS">{{Citiraj web|url=http://www.bssa.org.uk/cms/File/SSAS2.81-Magnetic%20Properties.pdf|title=Magnetic Properties of Stainless Steel|author=British Stainless Steel Association|publisher=Stainless Steel Advisory Service|year=2000}}</ref>  
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|[[Aluminij]]
|[[Aluminij]]
| 2.22 · 10<sup>-5</sup> <ref name="clarke">{{cite web|author=Richard A. Clarke |url=http://www.ee.surrey.ac.uk/Workshop/advice/coils/mu/ |title=Clarke, R. '&#39;Magnetic properties of materials'&#39;, surrey.ac.uk |publisher=Ee.surrey.ac.uk |date= |accessdate=2011-11-08}}</ref>
| 2.22 · 10<sup>-5</sup> <ref name="clarke">{{Citiraj web|author=Richard A. Clarke |url=http://www.ee.surrey.ac.uk/Workshop/advice/coils/mu/ |title=Clarke, R. '&#39;Magnetic properties of materials'&#39;, surrey.ac.uk |publisher=Ee.surrey.ac.uk |date= |accessdate=2011-11-08}}</ref>
| 1.256665 · 10<sup>-6</sup>
| 1.256665 · 10<sup>-6</sup>
| 1.000022
| 1.000022
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| 1 <ref>{{cite web|author=NDT.net |url=http://www.ndt.net/article/ndtce03/papers/v078/v078.htm |title=Determination of dielectric properties of insitu concrete at radar frequencies |publisher=Ndt.net |date= |accessdate=2011-11-08}}</ref>
| 1 <ref>{{Citiraj web|author=NDT.net |url=http://www.ndt.net/article/ndtce03/papers/v078/v078.htm |title=Determination of dielectric properties of insitu concrete at radar frequencies |publisher=Ndt.net |date= |accessdate=2011-11-08}}</ref>
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Inačica od 00:11, 1. prosinca 2021.

Specifična vodljivost je električna vodljivost žice presjeka 1 mm2 dužine 1m.
Pojednostavljeni usporedni pregled magnetske permeabilnosti: feromagnetika (μf), paramagnetika(μp), vakuuma (μ0) i dijamagnetika (μd).

Magnetska vodljivost (oznaka Λ) šipke ili žice, ploštine poprječnoga presjeka S i duljine l, dana je izrazom:

[math]\displaystyle{ \Lambda=\mu \cdot \frac{S}{l} }[/math]

gdje je: μ - magnetska permeabilnost; recipročna je vrijednost reluktancije (magnetskoga otpora) magnetskoga kruga; mjerna je jedinica henri (H). [1]

Magnetska permeabilnost

Vista-xmag.pngPodrobniji članak o temi: Magnetska permeabilnost

Magnetska permeabilnost je elektromagnetna osobina materijala koja pokazuje intenzitet magnetizacije tijela kada su ona izložena vanjskim magnetnom polju. Magnetska permeabilnost se označava grčkim slovom mi (μ). Pojam magnetska permeabilnost osmislio je Oliver Heaviside 1885. U jedinicama SI sustava, permeabilnost se izražava u Henrijima po metru (H/m), ili u Newtonima po Amperu na kvadrat (N/A2) ili Volt · sekunda na Amper · metar {Vs/Am}.

Magnetska permeabilnost vakuuma ili univerzalna magnetska konstanta (znak [math]\displaystyle{ \mu_0 }[/math]) je prirodna konstanta magnetske permeabilnosti za vakuum, koja iznosi: [math]\displaystyle{ \mu_0 }[/math]= 4π · 10–7 H/m [2] ili [math]\displaystyle{ \mu_0 }[/math] = 12.566370614 · 10–7 N/A². Jednaka je recipročnoj vrijednosti umnoška dielektrične permitivnosti vakuuma ε0 i kvadrata  brzine svjetlosti c u vakuumu: μ0 = 1/(ε0c2). [3]

Vrijednosti za neke materijale

Magnetna susceptibilnost i permeabilnost za odabrane materijale
Materijal Susceptibilnost χm
(volumetrijski SI) 		Permeabilnost μ [H/m] Relativna permeabilnost μ/μ0 Magnetsko polje Frekvencija (max.)
Metglas 1.26 · 100 1 000 000 [4] kod 0.5 T 100 kHz
Željezo (99.95% čisto Fe normalizirano u H) 2.5 · 10-1 200 000 [5]
Nanoperm 1.0 · 10-1 80 000 [6] kod 0.5 T 10 kHz
Mu-metal 2.5 · 10-2 20 000 [7] kod 0.002 T
Mu-metal 6.3 · 10-2 50 000 [8]
Kobalt-željezo (trake visoke permeabilnosti) 2.3 · 10-2 18 000 [9]
Permalloy 8 000 1.0 · 10-2 8 000 kod 0.002 T
Željezo (99.8% čisto) 6.3 · 10-3 5 000
Električarski čelik 5.0 · 10-3 4 000 kod 0.002 T
Feritični nehrđajući čelik (normaliziran) 1.26 · 10-3 - 2.26 · 10-3 1 000 – 1 800[10]
Martenzitni nehrđajući čelik (normaliziran) 9.42 · 10-4 - 1.19 · 10-3 750 – 950
Ferit (manganski cink) > 8.0 · 10-4 640 (ili više) 100 kHz ~ 1 MHz
Ferit (niklov cink) 2.0 · 10-5 - 8.0 · 10-4 16 – 640 100 kHz ~ 1 MHz
Ugljični čelik 1.26 · 10-4 100 kod 0.002 T
Nikal 1.26 · 10-4 - 7.54 · 10-4 100 – 600 kod 0.002 T
Martenzitni nehrđajući čelik (kaljen) 5.0 · 10-5 - 1.2 · 10-4 40 – 95
Austenitni nehrđajući čelik 1.26 · 10-6 - 8.8 · 10-6 1.003–7 [11]
Neodimijev magnet 1.32 · 10-6 1.05 [12]
Platina 1.25697 · 10-6 1.000265
Aluminij 2.22 · 10-5 [13] 1.256665 · 10-6 1.000022
Drvo 1.25663760 · 10-6 1.00000043
Zrak 1.25663753 · 10-6 1.00000037 [14]
Beton (suhi) 1 [15]
Vakuum 0 4π × 10−7 (μ0) 1 (točno, po definiciji)
Vodik -2.2 · 10-9 [13] 1.2566371 · 10-6 1.0000000
Teflon 1.2567 · 10-6 [7] 1.0000
Safir -2.1 · 10-7 1.2566368 · 10-6 0.99999976
Bakar -6.4 · 10-6 ili -9.2 · 10-6 [13] 1.256629 · 10-6 0.999994
Voda -8.0 · 10-6 1.256627 · 10-6 0.999992
Bizmut -1.66 · 10-4 1.25643 · 10-6 0.999834
Supravodič −1 0 0

Izvori

  1. ↑ vodljivost, [1] "Hrvatska enciklopedija", Leksikografski zavod Miroslav Krleža, www.enciklopedija.hr, 2014.
  2. ↑ The NIST reference on fundamental physical constants
  3. ↑ magnetska permeabilnost vakuuma, [2] "Hrvatska enciklopedija", Leksikografski zavod Miroslav Krleža, www.enciklopedija.hr, 2014.
  4. ↑ Predložak:Citiraj web
  5. ↑ Predložak:Citiraj web
  6. ↑ Predložak:Citiraj web
  7. ↑ 7,0 7,1 Predložak:Citiraj web
  8. ↑ Predložak:Citiraj web
  9. ↑ Predložak:Citiraj web
  10. ↑ Predložak:Citiraj web
  11. ↑ Predložak:Citiraj web
  12. ↑ Juha Pyrhönen, Tapani Jokinen, Valéria Hrabovcová (2009). Design of Rotating Electrical Machines. John Wiley and Sons. str. 232. ISBN 0-470-69516-1. http://books.google.com/?id=_y3LSh1XTJYC&pg=PT232 
  13. ↑ 13,0 13,1 13,2 Predložak:Citiraj web
  14. ↑ B. D. Cullity and C. D. Graham (2008), Introduction to Magnetic Materials, 2nd edition, 568 pp., p.16
  15. ↑ Predložak:Citiraj web
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