單元2實(shí)用閱讀課件

單元2實(shí)用閱讀

單元2實(shí)用閱讀

2.1ElectricalFundamentals

Mr.Adams:

I’dliketotalktoyouaboutelectricity,andIsupposethebestplacetostartwouldbetoask:whatiselectricity?Engineer: That’sahardone.Weknowagreatdealofelectricity,andwecanmakeitdoallsortsofthings,butit’sverydifficulttodefineexactlywhatitis.Onewaymightbetosaythatelectricityconsistsofaquantityorstreamofelectrically-chargedparticles.Theseparticlescanbeintheformofstored-upenergyorinmotion.

2.1ElectricalFundamentals

Mr.Adams: Isupposeelectricityinmotionwouldbecalledanelectriccurrent.Engineer: That’sright.Wesometimesexplainelectricaleffectsbydrawingacomparisonwithwatermovinginaclosedsystem.Ageneratorcanthenbethoughtofasakindofpumpthatpushestheelectricitythroughacompletecircuit.Theelectricwiresarelikethehollowcentersofpipes,insulationcorrespondstothepipesthemselvesandswitchesarelikevalves.Mr.Adams: IsupposeelectriciMr.Adams: Whatmakesinsulationactthewayitdoes?Engineer: Certainsubstances,forreasonsthatwedon’talwaysunderstandverywell,blocktheflowofelectriccurrent[1].Wecalltheminsulatorsornon-conductors.Othersubstances,metalsespecially,areverygoodconductors.Mr.Adams: WhatmakesinsulatiMr.Adams: Arethereothersimilaritiesbetweenelectricityandthewatersystemthatyoutalkedabout?Engineer: Yes.Justasyoucanpumpmorewaterthroughbiggerpipes,youcanpumpmoreelectricitythroughbiggerconductors.Themechanicalresistanceinpipestotheflowofwater,inotherwords,thefrictioncorrespondstoelectricalresistance.Thethinnerthewireorthepoorertheconductor,themoreresistanceyouhave[2].Thiselectricalfrictiontakestheformofheat.Mr.Adams: ArethereothersimMr.Adams: Inawatersystemthere’sapumpthatcreatespressureof,say,fortypoundspersquareinch.Canyouspeakofthepressureinanelectricalsystem?Engineer: Yes,butwecallitvoltage.Evenifnocurrentisflowing,thevoltageistherewhilethegeneratorisoperating.Whenthecircuitisclosed,thecurrentflows.Mr.Adams: InawatersystemtMr.Adams: Whatarethemaincircuitelements?Engineer: Basically,therearethree:theresistor,thecapacitorandtheinductor.Theydifferfromeachotherinrelationtothevoltageandthecurrentflowingthroughthem.Mr.Adams: Canyoumakeitalittleclearer?Mr.Adams: WhatarethemaincEngineer: Yes.Iftherelationshipinvolvessimplythevoltageandthecurrent,theelementisaresistor.Inaddition,iftherelationshipislinear,forexample,ifthevoltageisfivetimesthecurrent,thenwehavealinearresistor,anditspropertyiscalledresistance.Or,therelationshipmayinvolvethecurrentthroughtheelementandthetimederivativeofthevoltageacrossit.Inthiscase,theelementisacapacitor,anditspropertyiscalledcapacitance.Andaninductoristheelementinwhichthevoltageandthetimederivativeofthecurrentareinvolved].Engineer: Yes.IftherelationPhrasesandExpressions1．a(chǎn)llsortsof 各種2．consistof 由……組成3．electriccurrent 電流4．bethoughtofas 被認(rèn)為5．electricwire 電線6．explainsomethingby 借助于……解釋?zhuān)ㄟ^(guò)……解釋PhrasesandExpressions1．a(chǎn)lls重點(diǎn)句子[1]Certainsubstances,forreasonsthatwedon’talwaysunderstandverywell,blocktheflowofelectriccurrent.某些物質(zhì)阻礙電流的流動(dòng)——原因我們還不能完全清楚。這里，“forreasonsthatwedon’talwaysunderstandverywell”是插入語(yǔ)，修飾整個(gè)句子。重點(diǎn)句子[1]Certainsubstances,fo[2]Thethinnerthewireorthepoorertheconductor,themoreresistanceyouhave.導(dǎo)線越細(xì)或?qū)w的導(dǎo)電性能越差，電阻就越大。這里，句型“themore…，themore…”是固定句型，意為“越……就越……”。[2]Thethinnerthewireorth[3]Or,therelationshipmayinvolvethecurrentthroughtheelementandthetimederivativeofthevoltageacrossit.Inthiscase,theelementisacapacitor,anditspropertyiscalledcapacitance.Andaninductoristheelementinwhichthevoltageandthetimederivativeofthecurrentareinvolved.否則，這種關(guān)系可能會(huì)涉及到流過(guò)該元件的電流及其兩端電壓對(duì)時(shí)間的導(dǎo)數(shù)。這時(shí)，元件即為電容器，其屬性稱(chēng)為電容。當(dāng)關(guān)系涉及到元件兩端的電壓及流過(guò)元件的電流對(duì)時(shí)間的導(dǎo)數(shù)時(shí)，元件即為電感器。這里，throughtheelement以及acrossit分別為current與thevoltage的后置定語(yǔ)。另外，derivative是“導(dǎo)數(shù)”之意，…derivativeofx意為“x對(duì)……的導(dǎo)數(shù)”。[3]Or,therelationshipmayiExercises

Ⅰ．Whichofthefollowingareelementsandwhichareproperties? resistance inductor capacitor resistor inductance capacitanceⅡ．Speakoutthedifferencebetweencurrentandvoltage.ExercisesⅠ．Whichofthefollo2.2TheMKSSystemofUnits

TheCGSandtheMKSarethetwomostcommonlyusedmetricsystemsofunits.Theseinitialsmean“centimeters,grams,seconds”and“meters,kilograms,seconds.”Becauseofitslargerunits,theMKSsystemismoreconvenientforengineeringpurposes.Bothsystems,whenfirstintroduced,usedthreebasicquantities:length,massandtime.Thesearesufficientformeasurementsanddescriptionsofmechanicalphenomena.Todealwithelectromagneticphenomena,however,somefourth,electrical,quantityhastobeadded[1].TheMKSsystemusesanyofthefollowingasthefourthunit:ampere,volt,ohm,henry,farad,orcoulomb.Ofcourse,theseunitsarerelatedtoelectromagnetictheorysothatifoneisdefined,alltheotherscanbeworkedout.2.2TheMKSSystemofUnits

TOnJanuary1,1948,thefollowingresolutionswereadoptedbytheInternationalCommitteeonWeightsandMeasures[2]:1．Thenewtonistheforcewhichgivesthemassofonekilogramanaccelerationofonemeterpersecond.2．Thejouleistheworkdonewhenthepointatwhichonenewtonisappliedismovedbyonemeterinthedirectionoftheforce.3．Thewattisthepowerwhichcorrespondstotheproductionofenergyofonejoulepersecond.4．Theampereistheconstantcurrentwhich,ifflowingintwoparallelwires,whichareverylong,extremelythin,andplacedonemeterapartinavacuum,willproducebetweenthewiresaforceof2107newtonspermeteroflength.OnJanuary1,1948,thefollow5．Thevoltisthepotentialdifferencebetweentwopointsinawirecarryingacurrentofoneampere,wherethedissipatedpowerbetweenthesetwopointsisonewatt.6．Theohmistheresistancebetweentwopointsinabodyhavingapotentialdifferenceofonevoltwhenacurrentofoneampereisflowing.7．Thecoulombisthechargetransportedinonesecondbyacurrentofoneampere.8．Thefaradisthecapacitanceofacapacitorwithapotentialdifferenceofonevoltwhenitischargedwithachargeofonecoulomb.9．Thehenryistheinductanceofacircuitinwhichonevoltisproducedwhenthecurrentinthecircuitvariesbyoneamperepersecond.5．ThevoltisthepotentialdiPhrasesandExpressions1．metricsystemofunits 十進(jìn)單位制，公制2．dealwith 安排，處理，涉及3．workout 計(jì)算出，設(shè)計(jì)出，作出4．potentialdifference 電位差，電勢(shì)差PhrasesandExpressions1．metri重點(diǎn)句子[1]Todealwithelectromagneticphenomena,however,somefourth,electricalquantityhastobeadded.可是，為了處理電磁現(xiàn)象，我們必須引入第四個(gè)量，即電方面的某種量。這里請(qǐng)注意quantity的單數(shù)形式（不是quantities），即some意為“某種，某一個(gè)”，而不是“一些”之意。重點(diǎn)句子[1]Todealwithelectroma[2]InternationalCommitteeonWeightsandMeasures.國(guó)際度量衡委員會(huì)。[2]InternationalCommitteeonExercisesⅠ．Puttheproperpairsofwordsintheblankstomaketruestatements.The________isaunitof________.1．a(chǎn)mpere energyofwork2．coulomb charge3．farad power4．henry force5．joule current6．newton capacitance7．ohm potentialdifference8．volt resistance9．watt inductanceExercisesⅠ．PuttheproperpairⅡ．Useeachofthewordsinthefollowinglisttocompletethesentences. netwon second gram wire watt volt joule capacitance1．Thewattisthepowerwhichcorrespondstotheproductionofone_______persecond.2．Thevoltisthepotentialdifferencebetweentwopointsinawirecarryingacurrentofoneampere,wherethedissipatedpowerbetweenthesetwopointsisone________.3．Thestandardampereisdeterminedbymeasuringtheforcebetweentwoparallel_______inwhichcurrentisflowing.4．The_______isaunitofforce.5．Thecoulombisthechargetransportedinone______byacurrentofoneampere.6．Thefaradisameasureof_________.7．Thehenryistheinductanceofacircuitinwhichone_______isproducedwhenthecurrentofthecircuitvariesbyoneamperepersecond.8．CGSmeans“centimeters,____________,seconds.”Ⅱ．Useeachofthewordsinthe2.3ElectromotiveForce(EMF)

Inordertohaveasteadycurrentflowinaconductingpath[1],thepathmustformaclosedloop,orcompletecircuit.Otherwisechargewouldaccumulateattheendsoftheconductor,theresultingelectricfieldwouldchangewithtime,andthecurrentcouldnotbeconstant.2.3ElectromotiveForce(EMF)However,suchapathcannotconsistentirelyofresistance.Currentinaresistorrequiresanelectricfieldandanassociatedpotentialdifference.Thefieldalwaysdoespositiveworkonthecharge,which[2]alwaysmovesinthedirectionofdecreasingpotential.Butafteracompletetriparoundtheloop[3],thechargereturnstoitsstartingpoint,andthepotentialthere[4]mustbethesameaswhenitleftthatpoint.Itisimpossiblethatthetriparoundtheloopinvolvesonlydecreasesinpotential.However,suchapathcannotcoWecancomparethissituationwiththatofadecorativewaterfountain.Wateremergesfromopeningsatthetop,cascadesdownoverterracesandspouts,andeventuallyreachesthebasininthebottom.Itcollectsthereandrunsintoapumpthatliftsitbacktothetopforanothertrip.Iftherewerenopump,thewaterwouldnotbeabletocirculatecontinuously.WecancomparethissituationThusintheelectriccircuittheremustbesomepartoftheloopwhereachargetravels“uphill”,fromlowertohigherpotential,despitethefactthattheelectrostaticforceistryingtopushitfromhighertolowerpotential.Theinfluencethatmakeschargemovefromlowertohigherpotentialiscalledelectromotiveforce.ThusintheelectriccircuittPhrasesandExpressions

1．compareAwithB把A與B相比較2．despitethefactthat盡管PhrasesandExpressions1．comp重點(diǎn)句子[1]“inordertohaveasteadycurrentflowinaconductingpath”為不定式復(fù)合結(jié)構(gòu)形式的“inorderto”詞組，應(yīng)譯成“為了使穩(wěn)定的電流能在導(dǎo)電通路中流通”。[2]這個(gè)“which”引導(dǎo)一個(gè)非限制性定語(yǔ)從句，修飾前面的名詞“thecharge”。重點(diǎn)句子[1]“inordertohaveaste[3]“acompletetriparoundtheloop”可譯成“沿[繞]回路一周”。語(yǔ)法上講，“aroundtheloop”這一介詞短語(yǔ)做“trip”的后置定語(yǔ)。[4]“there”為單個(gè)副詞做后置定語(yǔ)，修飾前面的名詞“potential”，譯成“那兒的電位”。[3]“acompletetriparoundthExercisesⅠ．Translatethefollowingphrasesandexpressions.1．繞回路一周2．使電荷從較低電位運(yùn)動(dòng)到較高電位3．朝電位降低的方向運(yùn)動(dòng)4．inordertohaveasteadycurrentflowinaconductingpath5．theresultingelectricfield6．comparethissituationwiththatofadecorativewaterfountainExercisesⅠ．TranslatethefolloⅡ．TranslatethefollowingsentencesintoEnglish.1．假如地球上沒(méi)有空氣，我們就不能生存。2．要不是電子計(jì)算機(jī)，就不可能解出這道題。3．所有物質(zhì)，不論是水、鐵還是空氣，都是由原子構(gòu)成的。4．這種金屬必須是耐高溫的。5．看起來(lái)好像太陽(yáng)繞地球運(yùn)行似的。6．（作者）建議讀者不必記住這些公式。Ⅱ．TranslatethefollowingsentⅢ．TranslatethefollowingshortpassageintoChinese.Manyscientistshaveworkedatthetheoryofmagnetismsinceitsdiscovery.However,magnetismhaslongstoppedbeingaproblem.Atpresentanyofusknowsthatinmagneticmaterials,themoleculesthemselvesaretinymagnets,eachhavinganorthandasouthpole.Ifonehalvesabarmagnet,itwillbefoundthateachofthetwohalvesisacompletemagnethavinganorthpoleandasouthone.Inotherwords,weshallhavesimplytwosmallermagnetsinsteadofoneofalargersize,incaseourbarmagnetiscutintwo.Eitherofthesetwomagnetscould,inturn,becutintwowiththesameresultasbefore.Thisprocesscouldgoonindefinitely,eachsmallerpiecealwaysbeingamagnetjustliketheoriginalbarmagnet.Ifitwerepossibletodividethemagnetsuntilwereachedthemolecules,weshouldfindeachmoleculetobeamagnet.Ⅲ．Translatethefollowingshor2.4HowElectricityFlows

Electrons,asone[1]knows,areminute[2]negativechargesofelectricity.As[3]theseminutechargesmovealongawire,thatwireissaid[4]tocarryanelectriccurrent.Inotherwords,anelectriccurrentistheflowofelectronsthroughametalconductor.Thatiswhyelectronsplayaveryimportantroleintheformationofacurrent.Theelectronsflowalongawiremuchthesamewayaswaterrunsthroughapipe.2.4HowElectricityFlows

EleThoughtheelectronsmovefromminustoplus,theelectriccurrentisconventionallyconsideredtoflowfromthepositivetothenegativeterminal.ThoughtheelectronsmovefromInordertohaveasteadycurrent,wemusthaveacompletedcircuitthat[5]isalsocalled“closedcircuit”and[6]acontinuoussupplyofelectriccharge.(Theterms“closedcircuit”and“completedcircuit”beingsynonyms[7],weshallmeettheoneaswellas[8]theotherwhen[9]readingtechnicalliterature.)Anotherimportantfactorto[10]betakenintoconsiderationisthatcurrentstrengthisequalatallpointsofaseriescircuit.InordertohaveasteadycurrAshasjustbeenstated,theelectriccurrentflowsonlywhenthereisacompletedcircuitfromthenegativetothepositiveterminal.Thus,currentstartsflowingjustatthemoment[11]weclosethecircuit.Thereare,asisalreadyknowntoall[12],twokindsofcurrent:DCandAC,bothofwhich[13]areveryusefulinindustryaswellasinmanyotherfields.Ashasjustbeenstated,theePhrasesandExpressions1．thatiswhy 這就是……的理由；這就是為什么……2．muchthesamewayas 與……差不多一樣3．take…intoconsideration 把……考慮進(jìn)去；考慮（到）PhrasesandExpressions1．thatNotestotheText[1]“one”表示“人們，我們”之意。[2]“minute”為形容詞，意為“微小的”，不要與做名詞的“minute”相混淆。[3]“As”在此為連接詞，引導(dǎo)狀語(yǔ)從句，根據(jù)全句所表達(dá)的意思，應(yīng)選擇其“當(dāng)……時(shí)候”這一詞義。[4]“issaidto…”可譯成“被說(shuō)成……”或“人們說(shuō)……”。[5]“that”為關(guān)系代詞引導(dǎo)定語(yǔ)從句，從概念上看來(lái)，應(yīng)把它分譯成單獨(dú)的一句，可放在括號(hào)內(nèi)，即“也稱(chēng)之為closedcircuit”。NotestotheText[1]“one”表示“人們[6]“and”連接的是兩個(gè)并列的名詞短語(yǔ)，即“acompletedcircuit”和“acontinuoussupplyofelectriccharge”。[7]“Theterms…beingsynonyms”為分詞獨(dú)立結(jié)構(gòu)，放在主語(yǔ)前做原因狀語(yǔ)。[8]“aswellas”在此的功用就等效于“and”，意為“和、以及”。[9]這個(gè)狀語(yǔ)從句連接詞放在分詞短語(yǔ)前，表明是時(shí)間狀語(yǔ)。。[6]“and”連接的是兩個(gè)并列的名詞短語(yǔ)，即“acomp[10]“totakeintoconsideration”為不定式短語(yǔ)處于主謂之間做主語(yǔ)的定語(yǔ)。[11]在“moment”后省去了關(guān)系副詞“when”，所以“weclosethecircuit”為定語(yǔ)從句，修飾“themoment”。[12]“all”意為“大家、所有的人”。[13]關(guān)系代詞“which”指的就是“DCandAC”，它引導(dǎo)了一個(gè)非限制性定語(yǔ)從句，來(lái)修飾“DCandAC”的。[10]“totakeintoconsideratioExercisesⅠ．Translatethefollowingphrasesandexpressions.1．被說(shuō)成載有電流2．在形成電流方面起十分重要的作用3．要考慮的另外一個(gè)重要因素4．muchthesamewayaswaterrunsthroughapipe5．justatthemomentweclosethecircuit6．veryusefulinindustryaswellasinmanyotherfieldsExercisesⅠ．TranslatethefolloⅡ．TranslatethefollowingsentencesintoEnglish.1．正如圖1所示，電子繞原子核運(yùn)動(dòng)。2．顧名思義，電流就是電在導(dǎo)體中的流動(dòng)。3．正如我們將會(huì)看到的那樣，速度是一個(gè)矢量。4．如上所述，無(wú)線電波是一種特殊的波。5．像我們用來(lái)測(cè)量速度的這種儀表稱(chēng)為速度計(jì)。6．如在物理學(xué)中出現(xiàn)的有些方程是微分方程。Ⅱ．TranslatethefollowingsentⅢ．TranslatethefollowingshortpassageintoChinese.OneofthemostusefulequivalentcircuitsistheonethatresultsfromThevenin’stheorem,whichstatesthatanynetworkofresistorsandbatterieshavingtwooutputterminalsmaybereplacedbytheseriescombinationofaresistorandabattery,asisillustratedinFig.7.TheformoftheTheveninequivalentcircuitshowsimmediatelyhowthepropervaluesofVeqⅢ．TranslatethefollowingshorandReqcanbedeterminedwithoutknowingtheactualconfigurationofthenetworkitself.TheequivalentEMFisjustthepotentialattheoutputterminalswhentheloadcurrentiszero,thatis,theopen-circuitvoltage.TheequivalentresistanceisthentheratioofVeqtotheloadcurrentwhenRL0,ortotheshort-circuitcurrent.NotealsothatReqisequaltotheresistanceforwhichthevoltageacrosstheloadisone-halfofVeq.Thisisusefulinsituationswheretheshort-circuitcurrentcannotbeeasilydetermined.TheformoftheTheveninequivalentcircuitalsoshowstheReqistheresistanceofthenetworkbetweentheoutputterminalswhenVeqisconsideredtobereplacedbyashortcircuit.andReqcanbedeterminedwith2.5TheTransformers

One[1]cannotcallatransformeramachine,for[2]ithasnomovingparts.Weknowthetransformertobeanapparatuswhich[3]isdesignedforchangingthealternatingvoltagesandalternatingcurrentsbymeansofelectromagneticinductionwithoutanychangeoffrequency.2.5TheTransformers

One[1]ccurrentistheeaseandefficiencywithwhich[4]poweratlowvoltagemaybetransformedintoanalmostsimilaramountofpowerathighvoltage,andviceversa.Usingatransformer[5],itispossibletotransmitthealternatingcurrenttoverydistantplacesatwhichthepowerisrequired.currentistheeaseandefficiAtwo-windingtransformerisknownto[6]consistoftwocoilswhicharesoarrangedthat[7]themagneticlinesofforceofonecoilpassthroughtheother.ThealternatingcurrentinonecoilinducesanEMFintheotherbecauseofthealternationsinthevalueofthecoilcurrent.Atwo-windingtransformeriskInordertostrengthenthemagneticfieldpassingthroughthecoilsofatransformer,aclosedcoreofironisgenerallyused.Thecoilonwhichthecurrentisimpressedontheinputsideofthetransformeriscalledtheprimary,while[8]theone[9]fromwhichtheinducedcurrentisobtainedontheoutputsideiscalledthesecondary.InordertostrengthenthemagThepoweroutputofatransformerisnecessarilylessthanthepowerinputbecauseofunavoidablelosses.Theselossesincluderesistancelossesintheprimaryandsecondarywindings,andlossesinthecoredueto[10]hysteresisandeddycurrents.ThepoweroutputofatransforPhrasesandExpressions1．transformAintoB 把A轉(zhuǎn)換成B2．viceversa 反過(guò)來(lái)（也是一樣）3．passthrough 通過(guò)4．dueto 由于……（而引起的）；應(yīng)歸于5．bacauseof 由于，因?yàn)镻hrasesandExpressions1．transNotestotheText[1]“one”表示“人們、我們”之意，語(yǔ)法上只表示單數(shù)第三人稱(chēng)。[2]“for”在此為并列連接詞（因?yàn)樵谒竺媸且粋€(gè)完整的句子），表示“由于、因?yàn)椤?，但語(yǔ)氣極弱，語(yǔ)言學(xué)家們不把它引出的句子看成是一個(gè)狀語(yǔ)從句，而看成是一個(gè)等立句。[3]“tobeanapparatuswhich…”為不定式短語(yǔ)做賓語(yǔ)補(bǔ)足語(yǔ)，是動(dòng)詞know要求的。本句比較長(zhǎng)，可譯成“我們知道，變壓器是旨在利用電磁感應(yīng)來(lái)改變交變電壓和交變電流而頻率保持不變的一種器件。”NotestotheText[1]“one”表示“人們[4]“withwhich”開(kāi)頭的這個(gè)定語(yǔ)從句是修飾其前面的名詞“easeandefficiency”的，它本身在從句中做狀語(yǔ)。要注意之所以這里用了“with”是因?yàn)椤皐ith某些抽象名詞”就等效于該名詞對(duì)應(yīng)的副詞，如：witheaseeasily；withefficiencyefficiently；withdifficultydifficultly；withcarecarefully等。本句的漢譯不必按語(yǔ)法死譯，可以譯成“交流電突出的優(yōu)點(diǎn)之一是簡(jiǎn)單而有效地將低壓功率轉(zhuǎn)換成幾乎等量的高壓功率，反之亦然”。[4]“withwhich”開(kāi)頭的這個(gè)定語(yǔ)從句是修飾其前面[5]“Usingatransformer”為分詞短語(yǔ)，處于句子主語(yǔ)前作狀語(yǔ)，譯成“如果使用變壓器”。[6]“toconsistoftwocoilswhich…”為不定式短語(yǔ)做主語(yǔ)補(bǔ)足語(yǔ)，是名詞know要求的。[7]“that”引導(dǎo)結(jié)果狀語(yǔ)從句，與前面的副詞“so”搭配使用。整個(gè)句子譯成“我們知道雙繞組變壓器是由兩個(gè)線圈組成的，這兩個(gè)線圈的排列方式能使一個(gè)線圈的磁力線通過(guò)另一個(gè)線圈”。[5]“Usingatransformer”為分詞短語(yǔ)，[8]“while”引導(dǎo)的狀語(yǔ)從句表示“對(duì)照”，譯成“而”。[9]“one”是代詞，代替前面已出現(xiàn)過(guò)的名詞“coil”。[10]“duetohysteresisandeddycurrents”為形容詞短語(yǔ)，在此做后置定語(yǔ)修飾“l(fā)osses”，譯成“由于磁滯現(xiàn)象和渦流電流而在鐵芯中引起的損耗”。[8]“while”引導(dǎo)的狀語(yǔ)從句表示“對(duì)照”，譯成“而”。ExercisesⅠ．Translatethefollowingphrasesandexpressions.1．運(yùn)動(dòng)的部件2．改變交變電壓和交變電流而頻率保持不變3．幾乎等量的高壓功率4．theeasewithwhichpowercanbechanged5．lossesduetohysteresisandeddycurrents6．thealternationsinthevalueofthecoilcurrentExercisesⅠ．TranslatethefolloⅡ．TranslatethefollowingsentencesintoEnglish.1．電流在電路中流動(dòng)的速度是非?？斓?。2．這兩個(gè)線圈是如此安排的以致于一個(gè)線圈的磁力線能通過(guò)另一個(gè)線圈。3．從中獲得感應(yīng)電流的線圈被稱(chēng)為次級(jí)。4．我們測(cè)量電壓所用的儀表稱(chēng)為伏特表。Ⅱ．Translatethefollowingsent5．這個(gè)電流流動(dòng)所沿順的電路很簡(jiǎn)單。6．其中不存在自由電子的物質(zhì)稱(chēng)為絕緣體。7．在我們所熟悉的儀表中，萬(wàn)用表最常用。8．這兩個(gè)定律是建立其他定律的基礎(chǔ)。5．這個(gè)電流流動(dòng)所沿順的電路很簡(jiǎn)單。Ⅲ．TranslatethefollowingshortpassageintoEnglish.OneofthegreatadvantagesofACoverDCforelectricpowerdistributionisthatitismucheasiertostepvoltagelevelsupanddownwithACthanwithDC.Forlong-distancepowertransmissionitisdesirabletouseashighavoltageconversionascanbeaccomplishedbyuseoftransformers.Atransformerisacomponentconsistingoftwoormorecoilsthatarecoupledtogetherbymagneticinduction.Owingtothisdevicethepowermaybetransmittedatahighvoltage,andreducedattheplaceatwhichitisrequiredtoavaluesuitableforelectricmotorsandothermachines.Ⅲ．TranslatethefollowingshorThecoiltowhichthevoltageisappliedisknownastheprimary,whiletheonefromwhichtheinducedvoltageisobtainedisknownassecondary.Ifthesecondaryhasmoreturnsthantheprimary,thetransformeriscalledastep-uptransformerinwhichtheACvoltageofthesecondarywindingishigherthanthatappliedtotheThecoiltowhichthevoltage2.6Microphones

Therearemanydifferenttypesofmicrophones[1],butallofthemsharesomecommondesigngoals.First,microphonesmustchangesoundenergyintoelectricalenergytoproducethegreatestpossible[2]electricalsignalforagivensound.Second,theyareoftendesignedtohavethewidestpossiblefrequencyresponse.2.6Microphones

TherearemanThird,theyareplannedsothat[3]electricalsignals,intowhich[4]thesoundhasbeenconverted,canreproducethosesounds.Fourth,theyaredesignedtogivealinearresponsetovariationsinsoundenergy.Forexample,doublingtheenergyinthesound[5]waveshouldlikewisedoubletheenergyinthegeneratedelectricalwave.Third,theyareplannedsothaAmongotherqualitiesofmicrophonedesignare[6]sensitivityanddirectivity,which[7]dependontheparticularapplication.Forexample,onlyinamicrophoneusedtorecordmusicis[8]highsensitivityover[9]awiderangeoffrequencieswanted.Forpropersoundreproduction,eventhelowestamplitudesoundsatrelativelylongdistancesmustbeconvertedtoelectricalwaves.AmongotherqualitiesofmicroBycontrast,lowsensitivityisdesirableinamicrophoneusedinanaircraftbecauseofthehighbackgroundnoiselevel.Inthiscase,themicrophoneneed[10]onlyrespondtohighintensitysounds,likethoseofavoiceafewinchesaway[11].Bydirectivityismeant[12]theabilityof[13]themicrophonetopickupsoundsfromvariousdirections.Directivityalsodependsontheparticularapplication.Bycontrast,lowsensitivityiPhrasesandExpressions1．bycontrast 對(duì)比起來(lái)，相形之下；相反；而2．respondto 與……相對(duì)應(yīng)；響應(yīng)；對(duì)……起反應(yīng)3．pickup 拾起；采集；獲得；接收到PhrasesandExpressions1．bycoNotestotheText[1]這是一個(gè)“therebe”句型，所以應(yīng)譯成“話筒具有許多種不同的類(lèi)型”。[2]“thegreatestpossibleelectricalsignal”也可寫(xiě)成“thegreatestelectricalsignalpossible”，意為“可能的最大電信號(hào)，盡可能大的電信號(hào)”。[3]“sothat”為復(fù)合連接詞引導(dǎo)結(jié)果狀語(yǔ)從句，譯成“以致于”?！皌heyareplannedsothat”可譯成“把它們?cè)O(shè)計(jì)成使……”NotestotheText[1]這是一個(gè)“ther[4]“intowhich”為非限制性定語(yǔ)從句，修飾名詞“electricalsignal”，譯成漢語(yǔ)時(shí)可以把它定到名詞上去。[5]“doublingtheenergyinthesound”為動(dòng)名詞短語(yǔ)做主語(yǔ)。[6]“Amongotherqualitiesofmicrophonedesignare…”為“表語(yǔ)連系動(dòng)詞主語(yǔ)”全倒裝句型，譯成“在話筒設(shè)計(jì)的其他質(zhì)量（因素）之中有……”。[4]“intowhich”為非限制性定語(yǔ)從句，修飾名詞“[7]“which”引導(dǎo)的非限制性定語(yǔ)從句修飾的是“sensitivity”和“directivity”兩個(gè)名詞，因?yàn)閺木渲械膭?dòng)詞采用了“depend”的形式，說(shuō)明“which”代替的是復(fù)數(shù)名詞（兩個(gè)或兩個(gè)以上的事物）。[8]“is”屬于部分倒裝而處于句子主語(yǔ)之前了，正常情況下它應(yīng)處于“wanted”之前。[9]“over”表示“在……范圍內(nèi)”。[7]“which”引導(dǎo)的非限制性定語(yǔ)從句修飾的是“sens[10]“need”從主語(yǔ)為單數(shù)第三人稱(chēng)可知，它是個(gè)情態(tài)動(dòng)詞而不是實(shí)意動(dòng)詞，所以沒(méi)有人稱(chēng)變化，其后面跟有主要?jiǎng)釉~的動(dòng)詞原形“respond”，兩者合成謂語(yǔ)。[11]“afewinchesaway”為“數(shù)量狀語(yǔ)副詞”做后置定語(yǔ)修飾“avoice”，譯成“幾英寸以外的（遠(yuǎn)的）……”。[12]“ByAismeantB”是一個(gè)比較常見(jiàn)的部分倒裝句型，它屬于“介詞短語(yǔ)（狀語(yǔ)）被動(dòng)語(yǔ)態(tài)謂語(yǔ)主語(yǔ)（或主語(yǔ)從句）”句型，譯成“所謂A指的是B”。[13]“of”引出了一個(gè)類(lèi)似性不定式復(fù)合結(jié)構(gòu)做“ability”的定語(yǔ)。[10]“need”從主語(yǔ)為單數(shù)第三人稱(chēng)可知，它是個(gè)情態(tài)動(dòng)詞ExercisesⅠ．Translatethefollowingphrasesandexpressions.1．共同的設(shè)計(jì)目標(biāo)2．盡可能大的頻率響應(yīng)3．幾英尺以外的話音4．thegreatestpossibleelectricalsignal5．a(chǎn)linearresponsetovariationsinsoundenergy6．theabilityofthemicrophonetopickupsoundsfromvariousdirectionExercisesⅠ．TranslatethefolloⅡ．TranslatethefollowingsentencesintoEnglish.1．這一現(xiàn)象我們稱(chēng)之為電磁感應(yīng)。2．只有在這種情況下才有可能確定這兩點(diǎn)之間的距離。3．在這一頁(yè)上還畫(huà)出了電視機(jī)的方框圖。4．繞太陽(yáng)運(yùn)行的是稱(chēng)為行星的天體。5．導(dǎo)線中的電子絕不能從正極流向負(fù)極。6．在這兩點(diǎn)之間出現(xiàn)了一個(gè)電位差。Ⅱ．TranslatethefollowingsentⅢ．TranslatethefollowingshortpassageintoChinese.Youhaveseenhowamplifiersfunctioninelectroniccircuits.Nolessimportantareoscillators.Mostmodernradioreceiversyouhaveusedinyourhomecontainoscillators.Everytransmitterthatsendsinformationthroughtheairemploysanoscillatortoproducesignals.Thisisnotonlytrueofthestationsontheground,itappliestoeverytransmitteronashiporinaplane.Radiocommunicationsofeverykindwouldbegreatlylimitedifoscillatorcircuitswerenotavailable.Ⅲ．TranslatethefollowingshorNotareoscillatorsusedexclusivelyincommunicationsequipment.Mostofthetestequipmentyouuse,suchassignalgenerators,frequencymetersandsoon,containsoscillatorcircuits.Youwillfindoscillatorsinradarandlineequipment.Thebasicfunctionofanoscillatoristogenerateanalternatingvoltageatadesiredfrequency.Anelectronicoscillatorhasasimplecircuit,consistingofacapacitorandacoilconnectedinparallel.Tounderstandhowsuchacircuitcanbemadetooscillate,itisonlynecessarytoconsiderwhathappenswhenacapNotareoscillatorsusedexclu2.7SequentialLogicCircuit

Indigitalcircuittheory,sequentiallogicisatypeoflogiccircuitwhoseoutputdependsnotonlyonthepresentinputbutalsoonthehistoryoftheinput.Thisisincontrasttocombinatoriallogic,whoseoutputisafunctionof,andonlyof,thepresentinput[1].Inotherwords,sequentiallogichasstorage(memory)whilecombinatoriallogicdoesnot.2.7SequentialLogicCircuit

Sequentiallogicisthereforeusedtoconstructsometypesofcomputermemory,othertypesofdelayandstorageelements,andfinitestatemachines.Mostpracticalcomputercircuitsareamixtureofcombinatorialandsequentiallogic.Therearetwotypesoffinitestatemachinethatcanbebuiltfromsequentiallogiccircuits:SequentiallogicisthereforeMooremachine:theoutputdependsonlyontheinternalstate.(Sincetheinternalstateonlychangesonaclockedge,theoutputonlychangesonaclockedgetoo).Mealymachine:theoutputdependsnotonlyontheinternalstate,butalsoontheinputs.Mooremachine:theoutputdSynchronoussequentiallogicNearlyallsequentiallogictodayis“clocked”or“synchronouslogic”logic：thereisa“clock”signal,andallinternalmemory(the“internalstate”)changesonlyonaclockedge.Thebasicstorageelementinsequentiallogicistheflip-flop.SynchronoussequentiallogicNThemainadvantageofsynchronouslogicisitssimplicity.Everyoperationinthecircuitmustbecompletedinsideafixedintervaloftimebetweentwoclockpulses,calleda“clockcycle”.Aslongasthisconditionismet(ignoringcertainotherdetails),thecircuitisguaranteedtobereliable.Synchronouslogicalsohastwomaindisadvantages,asfollows.Themainadvantageofsynchron1．Theclocksignalmustbedistributedtoeveryflip-flopinthecircuit.Astheclockisusuallyahigh-frequency