Henri

Za druge upotrebe pogledajte stranicu Henri (višeznačna odrednica).

Henri
Induktor sastavljen od žice namotane oko magnetnog jezgra koja se koristi za ograničavanje i vođenje indukovanog magnetnog polja.
Informacije o jedinici
Sistem	Izvedene jedinice SI sistema
Jedinica	Induktanca
Simbol	H
Imenovan po	Džozef Henri
Jedinična pretvaranja
1 H u ...	... je jednak sa ...
Osnovne jedinice SI sistema	1 kg⋅m2⋅s−2⋅A−2

Henri (eng. henry; simbol: H) je SI jedinica za indukciju. Ako je stopa promene struje u kolu 1 amper po sekundi i rezultujuća elektromotorna sila iznosi jedan volt, onda je induktivnost tog kola jedan henri.

Henri je definisan kao V·A^-1·s = m²·kg·s^-2·A^-2 u SI jedinicama. Jedinica je dobila ime po američkom naučniku Džozefu Henriju, američkom naučniku koji je otkrio elektromagnetnu indukciju nezavisno i u otprilike u isto vreme kada i Majkl Faradej (1791–1867) u Engleskoj.

Definicija

Induktivnost električnog kola je jedan henri kada električna struja koja se menja brzinom od jednog ampera u sekundi rezultira elektromotornom silom od jednog volta preko induktora:

$\displaystyle V(t)=L{\frac {dI}{dt}}$,

gde V(t) označava rezultujući napon u kolu, I(t) je struja kroz kolo, a L je induktivnost kola.

Henri je izvedena jedinica zasnovana na četiri od sedam osnovnih jedinica Međunarodnog sistema jedinica: kilogram (kg), metar (m), sekunda (s) i amper (A). Izražen u kombinacijama SI jedinica, Henri je:

${\text{H}}={\dfrac {{\text{kg}}{\cdot }{\text{m}}^{2}}{{\text{s}}^{2}{\cdot }{\text{A}}^{2}}}={\dfrac {{\text{N}}{\cdot }{\text{m}}}{{\text{A}}^{2}}}={\dfrac {{\text{kg}}{\cdot }{\text{m}}^{2}}{{\text{C}}^{2}}}={\dfrac {\text{J}}{{\text{A}}^{2}}}={\dfrac {{\text{T}}{\cdot }{\text{m}}^{2}}{\text{A}}}={\dfrac {\text{Wb}}{\text{A}}}={\dfrac {{\text{V}}{\cdot }{\text{s}}}{\text{A}}}={\dfrac {{\text{s}}^{2}}{\text{F}}}={\dfrac {\Omega }{\text{Hz}}}=\Omega {\cdot }{\text{s}},$

gde je: H = henri, kg = kilogram, m = metar, s = sekunda, A = amper, N = njutn, C = kulon, J = džul, T = tesla, Wb = veber, V = volt, F = farad, Ω = om, Hz = herc

Upotreba

Međunarodni sistem jedinica (SI) precizira da se simbol jedinice nazvane za osobu piše velikim slovom, dok se ime ne piše velikim slovom u tekstu rečenice, osim kada bi bilo koja reč na toj poziciji bila pisana velikim slovom, kao što je na početak rečenice ili u materijalu pomoću naslovnog velikog slova.

Nacionalni institut za standarde i tehnologiju Sjedinjenih Država preporučuje korisnicima koji pišu na engleskom da koriste množinu kao henrije.

Primene

Induktivnost zavojnice zavisi od njene veličine, broja zavoja i permeabilnosti materijala unutar i oko zavojnice. Formule se mogu koristiti za izračunavanje induktivnosti mnogih uobičajenih rasporeda provodnika, kao što su paralelne žice ili solenoid. Mala zavojnica sa vazdušnim jezgrom koja se koristi za podešavanje AM radija može imati induktivnost od nekoliko desetina mikrohenrija. Veliki namotaj motora sa mnogo obrtaja oko gvozdenog jezgra može imati induktivnost od stotina henrija. Fizička veličina induktivnosti je takođe povezana sa njenim strujnim nošenjem i otporskim ocenama napona.

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Spoljašnje veze

• Clemson Vehicular Electronics Laboratory: Inductance Calculator