物理專業(yè)英語(yǔ)洛倫茲力原文和翻譯

物理專業(yè)英語(yǔ)組別：19組專業(yè)：物理學(xué)姓名：9.5 THELORENTZFORCEAchargemovinginamagneticfieldexperiencesaforcewhichweshallcallmagnetic.eforceisdeterminedbythechangq,itsvelocityv,andthemagneticinductionBatthepointwheretheeisatthemontofebeingcnseed.ThetassmpinistatthemagnitudeoftheforceFisproportionaltoeachofthethreequantitiesq,v,andB.Inaddition,FcanbeexpectedtodependonthemutualorientationofthevectorsvandB.ThedirectionoftheerFshudbedeemidbythoeofvetrsvandB.o”cnr”cevcrFformthescalarqandthevectorsvandB,letusfindthevectorofvdBandthenmiythenmuytheresultobtainedythesclarq.TherstistheexprssinqBthasbeenestblsedexeietlythttheforceF

(91）acigonaemoviginamgeicildsderiedbytefruak] （9）Wherekisaproportionalityconstantdependingonthechoiceoftheunitsforthequantitiesinhefrua.tteeinmidthtthereasoningwhihdstoexrssn(.1mutynosbeconsiderdasthederainofEq.(9.32)hisreasningdoesnothaecnlseforce.ItsaimistohelpusmemorizeEq(9.32).Thecorrectnessofthisequationcanbeestablishedolyeprmetly.emtoet.)nenrdsainfeaeccn.TheunitofmagneticinductionB-thetesla-isdeterminedsothattheproportionalityconstantkinEq..2)qasunty.eneInSIuis,tiseutonbeoes] (93）Temagiueofthemgntcfreisn (4)WhereistheanlebewenthevecosvandB.tcanbeseenfrmEq.(.4)thtacageovgalngtelnsofamantcflddesnteprnetheainofamantcfce.ThemagneticforceisdirectedatrightanglestotheplanecontainingthevectorsvandB.Ifthechargeqispositive,thendirectionoftheforcecoincideswiththatofthevector[vB].Whereqisneatve,tedircinsofthevecorsFand[vB]areoposte(Fg..).Sincethemacforceisalasdirctdatrhtanlstothevelctyofadetsokneeeeteeyfadebyacingonitwithaconsatmagnticfed.Theforceexertedonachargedparticlethatissimultaneouslyinanelectricandamagneticfedisq] (3)TispeinwsotedfmterstsfepiesbyheuchhiitedkLrnz(1853~1928)andiscaldtheLrnzfoc.AuethttheeqismgwhthevcyvpaalltoastitiniewirealongwhichthecurrentIflows(Fig.9.7).AccordingtoEqs.(9.30)and(9.34),thechargeinthiscaseeprinesamaneicfrewhoemanideis0v0

2Ib

)Wherebisthedistancefromthechargetothewire.Theforceisdirectedtowardthewirewhenchargeispositiveifthedirectionsofthecurrentandmotionofthechargearethesame,andawayfromthewireifthesedirectionsareopposite(seeFig.9.7).Whenthechargeisnegative,thedietinoftheforceisreered,teotercodiinsbeigequa.Letusconsidertwolikepointchargesqandq2movingalongparallelstraightlineswiththe1evcyvthatismuchrthanc(Fg.98)Whenv,theelticfielddoestvtlyierrmheidofaoryhgs(eSc9.Teeoethemgntdeofte1elcrcforce Fe eetdontechrescnbecnieedeulto1Fe,1=Fe,2=Fe=0

qq12r

(3)Equations（9.21）and(9.33)giveusthefollowingexpressionforthemagneticforce

Fmetdntehgs:FFF0m1 m,2 m

qqv2412r4

(8)(hepoiinvecorrispereniuartov).tsfindtherobeneacdelticfstfollowsfmEq.9.7)nd938tatmv2v2e00c2

)[seeehveobtaindEq.(.39)neasponthtv<isratio，sehvs.，ThersFeand

Fm

aredrd.Figure98hasbendrwnrlieadeheree,esfeslneehetedirctosoftheeleticandmaneicfrcswillbetherveseofthseshwninthefigre.IspctonofE.9sosthttemantcfreiswaertntheoumboneafactorequaltothesquareofratioofthespeedofthechargetothatoflight.Theisthatthemncitrcinbeweengsisariice.Mmwddsaparifthespedoflihtweregea.9.5 洛倫茲力移動(dòng)磁場(chǎng)力的作用量q度v在磁中所在的位置和該時(shí)刻所對(duì)應(yīng)的磁感應(yīng)強(qiáng)度B力F與qvb，F(xiàn)的方向主要是靠v和B的。F由量q和矢量vB作用得到的，v與B的量q，表達(dá)為q[vB] (91）移動(dòng)電荷在磁場(chǎng)中所受力的作用F。式F=kq[vB] 2）k場(chǎng)例。須住91出92的住92。到92式度。磁感度B的單位——特斯拉——已經(jīng)被定義。所以與在9.32式中等比量k是單為F=q[vB] (3)力小F=qvBsin （9）是v和B的矢量夾角。從9.4式會(huì)受到力。磁場(chǎng)力的方向在v和BF矢量向與[vB]所指的方向相同，若所帶電量為負(fù)電荷，則與[vB]所指方向相反（見(jiàn)圖9.6）粒磁但產(chǎn)。電荷在既有電場(chǎng)又有磁場(chǎng)的空間中運(yùn)動(dòng)。受到的力為F=qE+q[vB] （95）這個(gè)表達(dá)式亨德克15319名倫。帶子q以速度v流I圖9.7據(jù)9.30和94在實(shí)驗(yàn)中受到力的大小為02IF=vqB=qv (3)b是指流I02I力的向直當(dāng)帶電力在樣。假設(shè)倆同荷qq沿著磁感應(yīng)線方向以相同的速度v運(yùn)動(dòng)其中v小于c1 2當(dāng)v《c見(jiàn)3電1場(chǎng)力的大小為可表示為1Fe,1=Fe,2=Fe=0

qq1