Kev txhais ntawm hluav taws xob tam sim no
Hauv tus neeg xyuas hluav taws xob xws li tooj liab, muaj cov electrons uas txav mus los ntawm qhov ceev ceev tab sis tsis khiav tawm ntawm cov hlau. Cov electrons uas tuaj yeem txav mus los tau hu ua cov electrons dawb. Txawm hais tias cov electrons txav mus los tau txhua qhov kev taw qhia, tsis muaj tag nrho cov electrons ntws mus rau hauv ib qho kev taw qhia tshwj xeeb. 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 ntawd lub zog hluav taws xob tshwm sim hauv cov xov hlau tooj liab. Qhov muaj lub zog hluav taws xob ua rau cov electrons dawb paub txog lub zog hluav taws xob F = q E = e E, qhov twg F = lub zog hluav taws xob , e = electron charge, E = lub zog hluav taws xob . Lub zog hluav taws xob no ua rau tag nrho cov electrons uas txav mus los ywj pheej nrawm ua ke, uas yog tib qho kev taw qhia li lub zog hluav taws xob.
Cov electrons dawb uas txav mus ua ke yog nyob nruab nrab ntawm cov atoms uas tseem nyob hauv cov hlau tooj liab kom tag nrho cov electrons sib tsoo nrog cov atoms. Qhov kev sib tsoo ua rau qhov kev taw qhia ntawm cov electrons dawb hloov pauv. Tag nrho cov electrons no ib txwm muaj lub zog hluav taws xob kom tag nrho cov electrons raug nrawm dua tib yam li qhov kev taw qhia ntawm lub zog hluav taws xob. Tom qab txav mus ib pliag, cov electrons dawb sib tsoo nrog cov atoms hauv cov hlau tooj liab. Tab sis cov electrons dawb ib txwm muaj lub zog hluav taws xob kom tag nrho cov electrons raug nrawm dua. Yog li ntawd, ntxiv rau kev txav mus los tsis tu ncua hauv ntau qhov kev taw qhia, tag nrho cov electrons dawb kuj txav qeeb qeeb ua ke hauv qhov kev taw qhia ntawm lub zog hluav taws xob thiab hauv qhov kev taw qhia rov qab rau 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. Qhov kev txav mus los tsis tu ncua ntawm txhua lub electron dawb muaj qhov ceev ceev heev, thaum qhov kev txav mus los nrog cov electrons dawb hauv qhov kev taw qhia ntawm lub zog hluav taws xob muaj qhov ceev qeeb heev. Qhov kev txav mus los no nrog cov electrons dawb hauv qhov kev taw qhia ntawm lub zog hluav taws xob kuj hu ua qhov ceev drift.
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 thaum lub sijhawm tshwj xeeb. Raws li daim ntawv cog lus, qhov kev taw qhia ntawm cov hluav taws xob tam sim no yog tib yam li qhov kev taw qhia ntawm qhov them zoo. Daim ntawv cog lus no tau ua ua ntej nws paub tias qhov tseeb txav mus rau hauv tus neeg xyuas hluav taws xob yog cov hluav taws xob dawb uas them tsis zoo. 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, yog tias peb tham txog qhov tam sim no ntws hauv tus neeg xyuas hluav taws xob, qhov txhais tau tias yog qhov ntws ntawm qhov them zoo, uas tseem hu ua tam sim no ib txwm muaj vim nws yog qhov tshwm sim ntawm daim ntawv cog lus.
Qhov sib npaug ntawm hluav taws xob tam sim no
Hauv lej, hluav taws xob tam sim no yog qhia los ntawm kab zauv:
Kuv = ΔQ / Δt
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 thib ob, yog li lub chav ntawm lub zog hluav taws xob yog Coulomb/thib ob. Coulomb/thib ob kuj hu ua Ampere, lub npe ntawm 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 uas hla dhau thaj tsam ntawm cov hlau rau 1 thib ob. Dhau li ntawm kev qhia hauv Amperes, cov zog hluav taws xob kuj tau qhia hauv milliamperes (1 mA = 10 -3 A), microamperes (1 μA = 10 -6 A), nano amperes (1 nA = 10-9 A) lossis picoamperes (1 pA = 10 -12 A).
Piv txwv teeb meem 1:
Muaj ib lub zog hluav taws xob ntawm 2 Amperes ntws hla lub xaim hlau li 8 vib nas this. Txheeb xyuas seb muaj pes tsawg lub zog hluav taws xob uas hla dhau ib qho thiab pes tsawg lub electrons hauv lub zog hluav taws xob ntawd!
Paub:
Tam sim no hluav taws xob (I) = 1 Ampere
Lub sijhawm luv (t) = 2 vib nas this
Xav tau: tus nqi (Q) thiab tus naj npawb ntawm cov electrons (e)
tshuaj:
Kev sib npaug ntawm hluav taws xob tam sim no:
Kuv = Q/t
Kuv = tam sim no, Q = lub zog hluav taws xob, t = lub sijhawm luv
Kev them hluav taws xob:
Q = It = (2 Ampere)(8 vib nas this) = 16 C.
Tus nqi ntawm ib lub electron yog 1.6 x 10 -19 Coulomb, yog li tus nqi ntawm 16 Coulombs muaj ntau lub electron li 16 C / 1.6 x 10 -19 Coulomb = 10 x 10 19 electron.
Lub zog hluav taws xob, qhov ceev ntawm lub zog hluav taws xob, thiab qhov ceev ntawm lub zog hluav taws xob
Tshuaj xyuas qhov them hluav taws xob zoo uas txav mus rau sab xis nrog qhov ceev, drifting v mus rau hauv qhov kev taw qhia ntawm lub teb hluav taws xob E.
ntawm tus neeg xyuas hluav taws xob uas muaj thaj tsam A. Tus nqi zoo txav mus deb li 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 hluav taws xob yog A s = A vt,
ces tus naj npawb ntawm cov khoom me me uas raug them hauv qhov ntim ntawm tus neeg coj hluav taws xob 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 hluav taws xob thaum lub sijhawm t yog Q = nq A v t. Yog li, cov hluav taws xob ntws los ntawm qhov kawg ntawm tus neeg coj hluav taws xob 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 hluav taws xob yog cov khoom ntawm kev sib npaug ntawm qhov ceev ntawm cov khoom me me (n),
tus nqi ntawm cov nqi rau txhua lub khoom me me (q), thaj tsam ntawm tus neeg coj hluav taws xob (A) thiab qhov ceev ntawm cov khoom me me uas tau them (v).
Kawm cov lus nug piv txwv hauv qab no.
Piv txwv teeb meem 2:
Ib qho tam sim no tas mus li ntawm 10 amperes ntws hauv ib txoj hlau tooj liab nrog thaj tsam ntawm 3 x 10 -6 m2 . Qhov ceev ntawm cov hluav taws xob dawb yog 8.4 x 10 28 electrons / m3 . Txheeb xyuas qhov ceev ntawm cov hluav taws xob dawb drift!
Paub:
Tam sim no hluav taws xob (I) = 10 Ampere
Thaj tsam hla ntawm cov hlau (A) = 3 x 10 -6 m 2
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
Xav tau: Qhov ceev ntawm kev hloov pauv hluav taws xob dawb (v)
tshuaj:
Qhov ceev ntawm cov electrons yog xam los ntawm kev siv cov mis uas tau muab los ua ntej:
Kuv = tam sim no hluav taws xob, n = qhov ceev ntawm cov khoom me me = qhov ceev ntawm cov hluav taws xob, q = ib qho hluav taws xob them, A = thaj tsam hla ntawm tus neeg coj hluav taws xob, v = qhov ceev ntawm cov hluav taws xob txav mus los
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 ntawm qhov ceev ntawm 0.248 millimeters ib ob. Hauv lwm lo lus, txhua ob, txhua lub hluav taws xob dawb txav mus txog 0.248 millimeters. Qhov no yog qhov ceev qeeb heev. Yog tias 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, cov hluav taws xob ntws hauv tus neeg coj hluav taws xob zoo li cov dej ntws 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 tam sim ntawd ntws tawm ntawm ib kawg ntawm lwm lub raj dej. Ib yam li ntawd, muaj cov hluav taws xob dawb hauv cov hlau tooj liab thiab cov teeb hluav taws xob. Thaum lub qhov hloov qhib, lub teb hluav taws xob tshwm sim nrog qhov ceev mus txog qhov ceev ntawm lub teeb (qhov ceev ntawm lub teeb = 3 x 10 8 meters / thib ob), uas ua rau cov hluav taws xob dawb pib txav mus ua ke thaum lub sijhawm ntawd. Twb muaj cov hluav taws xob dawb hauv cov hlau teeb hluav taws xob kom lub teeb nyob rau lub sijhawm ntawd.
Teeb meem thiab kev daws teeb meem
1. Muaj ib qho hluav taws xob uas ruaj khov ntawm 10 A nyob hauv ib txoj hlau rau 2 feeb. Muaj pes tsawg ntawm cov nqi hluav taws xob hla dhau tus neeg xyuas hluav taws xob ntawm txhua qhov chaw.
Paub:
Tam sim no hluav taws xob (I) = 10 A
Lub sijhawm sib nrug (t) = 2 feeb = 2 x 60 vib nas this = 120 vib nas this
Xav tau: Them (Q)
Tshuaj:
Kev sib npaug ntawm lub zog hluav taws xob:
Kuv = q/t
Kuv = tam sim no, q = lub zog hluav taws xob, t = lub sijhawm luv
Lub zog fais fab:
Q = Kuv = (10)(120) = 1200 C
2. 60 C ntawm lub zog them hla ib qho chaw hauv lub voj voog rau 5 feeb. Tam sim no hluav taws xob yog dab tsi?
Paub:
Lub sijhawm sib nrug (t) = 5 feeb = 5 x 60 vib nas this = 300 vib nas this
Lub zog hluav taws xob (Q) = 60 C
Xav tau: Lub zog hluav taws xob (I)
Tshuaj:
Lub zog hluav taws xob:
Kuv = Q/t
Kuv = 60 / 300
Kuv = 0.2 Coulombs/ob
Kuv = 0.2 Ampere
3. Lub chav ntawm hluav taws xob tam sim no hauv SI system yog…
tshuaj
Coulombs/ob
Coulombs/ vib nas this, muab lub npe tshwj xeeb, Ampere.
