Kev txhais ntawm hluav taws xob tam sim no
Sab hauv tus neeg xyuas hluav taws xob zoo li tooj liab, muaj cov electrons uas txav mus los tau yooj yim thiab tsis raws li qhov ceev ceev tab sis tsis khiav tawm ntawm cov hlau. Cov electrons uas tuaj yeem txav mus los tau yooj yim hu ua cov electrons dawb. Txawm hais tias cov electrons txav mus los tau yooj yim hauv txhua qhov kev taw qhia, tsis muaj cov electrons ntws mus rau txhua qhov kev taw qhia. Qhov xwm txheej no tshwm sim thaum tsis muaj qhov sib txawv ntawm ob qho kawg ntawm cov hlau tooj liab.
Thaum cov xov hlau txuas nrog lub zog hluav taws xob, qhov sib txawv ntawm ob sab ntawm cov xov hlau tooj liab, yog li tsim kom muaj lub zog hluav taws xob hauv cov xov hlau tooj liab. Qhov muaj lub zog hluav taws xob ua rau cov electrons dawb muaj lub zog hluav taws xob F = q E = e E, qhov twg F = lub zog hluav taws xob, e = lub zog hluav taws xob, E = lub zog hluav taws xob . Lub zog hluav taws xob ua rau txhua cov electrons uas txav mus los ywj pheej muaj kev nrawm nrawm hauv tib qho kev coj ua ntawm lub zog hluav taws xob.
Cov electrons dawb no, txav mus ua ke, nyob nruab nrab ntawm cov atoms nyob ruaj khov hauv cov hlau tooj liab, ua rau tag nrho cov electrons sib tsoo nrog cov atoms no. Cov kev sib tsoo no ua rau cov electrons dawb hloov lawv txoj kev txav mus los. Tag nrho cov electrons no raug lub zog hluav taws xob tas li, ua rau lawv nrawm dua tib yam li lub zog hluav taws xob. Tom qab txav mus ib pliag, cov electrons dawb sib tsoo dua nrog cov atoms hauv cov hlau tooj liab. Txawm li cas los xij, cov electrons dawb ib txwm raug lub zog hluav taws xob, ua rau tag nrho cov electrons nrawm dua.
Yog li, ntxiv rau kev txav mus los tsis raws cai hauv ntau qhov kev taw qhia, txhua lub electrons dawb kuj txav mus ua ke qeeb qeeb hauv qhov kev taw qhia ntawm lub zog hluav taws xob thiab hauv qhov kev taw qhia rov qab ntawm lub teb hluav taws xob. Qhov kev taw qhia ntawm lub teb hluav taws xob yog los ntawm lub zog hluav taws xob siab mus rau lub zog hluav taws xob qis, thaum cov electrons txav mus los ntawm lub zog qis mus rau lub zog siab. Kev txav mus los tsis raws cai ntawm txhua lub electron dawb muaj qhov ceev ceev heev, thaum kev txav mus los ua ke ntawm cov electrons dawb hauv qhov kev taw qhia ntawm lub zog hluav taws xob muaj qhov ceev qeeb heev. Qhov kev txav mus los ua ke ntawm cov electrons dawb hauv qhov kev taw qhia ntawm lub zog hluav taws xob kuj hu ua drift velocity.
Cov hluav taws xob tam sim no yog txhais tias yog qhov ntws ntawm cov nqi hluav taws xob los ntawm qhov hla ntawm tus neeg xyuas hluav taws xob dhau lub sijhawm tshwj xeeb. Los ntawm kev lig kev cai, qhov kev taw qhia ntawm cov hluav taws xob tam sim no yog tib yam li qhov kev taw qhia ntawm kev txav mus los ntawm cov nqi zoo. Daim ntawv cog lus no tau ua ua ntej nws paub tias qhov tseeb txav mus los hauv tus neeg xyuas hluav taws xob yog cov hluav taws xob dawb, tsis muaj nqi. Qhov kev taw qhia ntawm kev txav mus los ntawm cov hluav taws xob hauv tus neeg xyuas hluav taws xob yog qhov sib txawv ntawm qhov kev taw qhia ntawm cov hluav taws xob tam sim no. Yog li ntawd, thaum tham txog qhov tam sim no ntws hauv tus neeg xyuas hluav taws xob, qhov txhais tau tias yog qhov ntws ntawm cov nqi zoo, tseem hu ua tam sim no ib txwm muaj vim nws yog qhov tshwm sim ntawm daim ntawv cog lus no.
Cov mis hluav taws xob tam sim no
Hauv lej, hluav taws xob tam sim no yog qhia los ntawm kab zauv:
Kuv = ΔQ / Δt
Cov lus piav qhia txog tus qauv: Kuv = tam sim no, ΔQ = tus nqi hluav taws xob, Δt = lub sijhawm luv.
Chav ntawm hluav taws xob tam sim no
Lub chav ntawm lub zog hluav taws xob yog Coulomb, lub chav ntawm lub sijhawm yog qhov thib ob, yog li lub chav ntawm lub zog hluav taws xob yog Coulomb/thib ob. Coulomb/thib ob kuj hu ua Ampere , uas muaj npe tom qab tus kws tshawb fawb Fabkis, Andre Marie Ampere (1775-1836). 1 Ampere = 1 Coulomb/thib ob (1 A = 1 C / s). Hauv lwm lo lus, lub zog hluav taws xob ntawm 1 Ampere yog sib npaug rau lub zog hluav taws xob ntawm 1 Coulomb hla dhau thaj tsam ntawm cov hlau rau 1 thib ob. Dhau li ntawm kev qhia hauv Amperes, lub zog hluav taws xob kuj tseem qhia hauv milliamperes (1 mA = 10 -3 A), microamperes (1 μA = 10 -6 A), nanoamperes (1 nA = 10 -9 A) lossis picoamperes (1 pA = 10 -12 A).
Piv txwv lo lus nug 1:
Muaj ib lub zog hluav taws xob 2 Amperes ntws hla ib txoj hlau li 8 vib nas this. Txheeb xyuas seb lub zog hluav taws xob ntawd hla ib qho chaw li cas thiab seb muaj pes tsawg lub electrons hauv lub zog hluav taws xob ntawd!
Kev Sib Tham
Nws paub tias:
Tam sim no hluav taws xob (I) = 1 Ampere
Lub sijhawm luv (t) = 2 vib nas this
Nug: tus nqi (Q) thiab tus naj npawb ntawm cov electrons (e)
Lus teb:
Cov mis hluav taws xob tam sim no:
Kuv = Q/t
Cov lus piav qhia txog tus qauv: Kuv = tam sim no hluav taws xob, Q = nqi hluav taws xob, t = lub sijhawm luv
Kev them hluav taws xob:
Q = Kuv = (2 Ampere) (8 vib nas this) = 16 Coulombs.
Tus nqi ntawm ib lub electron yog 1,6 x 10 -19 Coulombs yog li tus nqi ntawm 16 Coulombs muaj ntau lub electrons li 16 C / 1,6 x 10 -19 Coulombs = 10 x 10 19 electrons.
Fais fab tam sim no, drift velocity thiab tam sim no density
Xav txog ib qho hluav taws xob zoo uas txav mus rau sab xis nrog qhov ceev ntawm v mus rau hauv qhov kev taw qhia ntawm lub teb hluav taws xob E hauv ib lub tshuab hluav taws xob uas muaj thaj tsam A. Lub hluav taws xob zoo txav mus deb s = vt thaum lub sijhawm t.
Yog tias tus naj npawb ntawm cov khoom me me uas raug them ib ntim (qhov ceev ntawm cov khoom me me uas raug them) yog n thiab qhov ntim ntawm tus neeg coj yog A s = A vt, ces tus naj npawb ntawm cov khoom me me uas raug them hauv qhov ntim ntawm tus neeg coj yog n A v t. Yog tias txhua lub khoom me me uas raug them muaj qhov them ntawm q ces qhov nqi ntawm cov nqi uas hla dhau qhov kawg ntawm tus neeg coj thaum lub sijhawm t yog Q = nq A v t. Yog li ntawd, qhov hluav taws xob uas ntws los ntawm qhov kawg ntawm tus neeg coj yog I = Q/t = nq A v. Thaum qhov ceev tam sim no lossis tam sim no ib cheeb tsam hla A yog J = I/A = nq v. Nws tuaj yeem xaus lus tias qhov tam sim no ntws hauv tus neeg coj yog qhov tshwm sim ntawm kev sib npaug ntawm qhov ceev ntawm cov khoom me me uas raug them (n), qhov loj ntawm qhov them ntawm txhua lub khoom me me (q), thaj tsam hla ntawm tus neeg coj (A) thiab qhov ceev ntawm cov khoom me me uas raug them (v).
Kawm cov piv txwv teeb meem hauv qab no kom nkag siab txog qhov sib txawv ntawm qhov ceev ntawm txhua lub khoom me me uas raug them thiab qhov ceev ntawm txhua lub khoom me me uas raug them.
Piv txwv lo lus nug 2:
Ib qho tam sim no tas mus li ntawm 10 Amperes ntws hauv cov hlau tooj liab nrog thaj tsam hla ntawm 3 x 10-6 m2Qhov ceev ntawm cov electron dawb yog 8,4 x 1028 electrons/m3Txheeb xyuas qhov ceev ntawm cov electrons dawb!
Kev Sib Tham
Nws paub tias:
Tam sim no hluav taws xob (I) = 10 Ampere
Thaj tsam hla ntawm cov hlau (A) = 3 x 10-6 m2
Qhov ceev ntawm cov hluav taws xob dawb (n) = 8,4 x 1028 m-3
Lub zog hluav taws xob (q) = 1,6 x 10-19 C
Nug: Qhov ceev ntawm cov hluav taws xob dawb (v)
Lus teb:
Qhov ceev ntawm cov electrons yog xam los ntawm kev siv cov mis uas tau muab ua ntej:
Kev piav qhia: Kuv = hluav taws xob tam sim no, n = qhov ceev ntawm cov khoom me me = qhov ceev ntawm cov hluav taws xob dawb, q = qhov them ntawm ib lub hluav taws xob, A = thaj tsam hla ntawm tus neeg coj, v = qhov ceev ntawm hluav taws xob
Qhov ceev ntawm electron drift yog 0,248 x 10 -3 meters/ob = 0,248 millimeters/ob.
Cov hluav taws xob dawb txav ua ke hauv ib txoj hlua hlau ntawm qhov ceev ntawm 0,248 millimeters ib ob. Hauv lwm lo lus, txhua ob tag nrho cov hluav taws xob dawb txav 0,248 millimeters. Qhov no yog qhov ceev qeeb heev. Yog tias qhov kev txav ntawm cov hluav taws xob dawb qeeb heev, vim li cas lub teeb hluav taws xob thiaj li tig tam sim ntawd tom qab lub qhov hloov qhib?
Yuav kom nkag siab qhov no, xav txog qhov ntws ntawm cov hluav taws xob hauv tus neeg xyuas hluav taws xob raws li qhov ntws ntawm dej hauv lub raj dej. Yog tias lub raj dej puv nrog dej, ces yog tias ib kawg ntawm lub raj dej txuas nrog lub kais dej, dej yuav ntws tawm ntawm qhov kawg tam sim ntawd. Ib yam li ntawd, muaj cov hluav taws xob dawb hauv cov hlau tooj liab thiab cov hlau teeb. Thaum lub qhov hloov qhib, lub teb hluav taws xob raug tsim nrog qhov ceev ze rau qhov ceev ntawm lub teeb (qhov ceev ntawm lub teeb = 3 x 108 meters / vib nas this), uas ua rau cov hluav taws xob dawb tam sim ntawd pib txav mus ua ke. Twb muaj cov hluav taws xob dawb hauv cov hlau teeb, yog li lub teeb tig tam sim ntawd.
