电子信息与通信工程专业英语lesson2-1(太原理工大学版)PPT课件下载推荐.ppt

电子信息与通信工程专业英语lesson2-1(太原理工大学版)PPT课件下载推荐.ppt

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Chapter2CircuitSystemandDesign第第二章二章电路系统与设计电路系统与设计Outline大纲大纲l2.1CircuitandSystem电路与系统电路与系统l2.2AnalogandDigitalCircuitsDesign模拟与数字电路设计模拟与数字电路设计l2.3RadioReceiverCircuit无线电接收机电路无线电接收机电路11/7/20221通信与信息工程专业英语教程2.1CircuitandSystemOutline大纲大纲lBasicconcepts基本概念基本概念lCircuitandSystem电路与系统电路与系统11/7/20222通信与信息工程专业英语教程Terminology术语lchargen.负荷,电荷,费用,主管,充电,充气,装料lconductivityn.传导性,传导率linsulatorn.绝缘体,绝热器lgravitationaladj.重力的lvoltagen.电工电压,伏特数lvoltsn.直流电压lamperen.安培lohmn.物欧姆lcoulombn.电库仑（电量单位）ldiametern.直径linductancen.感应系数,自感应11/7/20223通信与信息工程专业英语教程ldielectricn.电介质,绝缘体adj.非传导性的lfaradn.电法拉（电容单位）lpolarityn.极性lpotentialdifference电电位差，电势差lequivalentresistance等效电阻lSuperpositionTheorem叠加定理lTheveninsTheorem戴维南定理lNortonsTheorem诺顿定理11/7/20224通信与信息工程专业英语教程lIntheBohrtheoryoftheatom（namedafterNielsBohr,18851962）,electronsorbitanucleuscontainingneutronsandprotons.lElectricchargeismeasuredincoulombs.IntroductionTexttour文本浏览文本浏览BasicconceptsChargeandconductivity11/7/20225通信与信息工程专业英语教程lThisrelativemobilityofelectronswithinamaterialisknownaselectricconductivity.Conductivityisdeterminedbythetypesofatomsinamaterial（thenumberofprotonsineachatomsnucleus,determiningitschemicalidentity）andhowtheatomsarelinkedtogetherwithoneanother.11/7/20226通信与信息工程专业英语教程lItshouldalsobeunderstoodthatsomematerialsexperiencechangesintheirelectricalpropertiesunderdifferentconditions.lWhilethenormalmotionoffreeelectronsinaconductorisrandom,withnoparticulardirectionorspeed,electronscanbeinfluencedtomoveinacoordinatedfashionthroughaconductivematerial.Thisuniformmotionofelectronsiswhatwecallelectricity,orelectriccurrent.11/7/20227通信与信息工程专业英语教程lTherecanbeelectriccurrentonlywherethereexistsacontinuouspathofconductivematerialprovidingaconduitforelectronstotravelthrough.Ifthepathisblocked,theflowwillnotoccur.11/7/20228通信与信息工程专业英语教程Electriccircuits,voltageandcurrentlAnelectriccircuitisformedwhenaconductivepathiscreatedtoallowfreeelectronstocontinuouslymove.Thiscontinuousmovementoffreeelectronsthroughtheconductorsofacircuitiscalledacurrent,anditisoftenreferredtointermsofflow,justliketheflowofaliquidthroughahollowpipe.lTheforcemotivatingelectronstoflowinacircuitiscalledvoltage,whichtechnicallyisameasureofpotentialenergyperunitchargeofelectrons.lThemoremasssomethinghasandthehigherweliftit,themorepotentialenergyithas.11/7/20229通信与信息工程专业英语教程lOnevoltisdefinedasthatmagnitudeofelectromotiveforcerequiredcauseacurrentofoneamperetopassthroughaconductorhavingaresistanceofoneohm.lCurrentflowisrepresentedbythelettersymbolI.Thebasicunitinwhichcurrentismeasuredistheampere（amp）.Oneampereofcurrentisdefinedasthemovementofonecoulombpastanypointofaconductorduringonesecondoftime.11/7/202210通信与信息工程专业英语教程lFreeelectronstendtomovethroughconductorswithsomedegreeoffriction,oroppositiontomotion.Thisoppositiontomotionismoreproperlycalledresistance.lTheresistanceofamaterialthatfollowsOhmslawisconstant,orindependentofvoltageorcurrent,andtherelationshipbetweencurrentandvoltageislinear.lWheneveranelectricvoltageexistsbetweentwoseparatedconductors,anelectricfieldispresentwithinthespacebetweenthoseconductors.Electricalenergycanbestoredinanelectricfield.Thedevicetobecapableofdoingthisiscalledacapacitororacondenser.Resistance,capacitanceandinductance11/7/202211通信与信息工程专业英语教程lIfacondenserisconnectedtoabattery,theelectronswillflowoutofthenegativeterminalofthebatteryandaccumulateonthecondenserplateconnectedtothatside.Thusthecondenserissaidtobecharged.Thecapacitanceisdirectlyproportionaltothedielectricconstantofthematerialandtotheareaoftheplatesandinverselytothedistanceoftheplates.Thelargertheplatearea,thesmallerthespacebetweenthem,thegreaterthecapacitance.lWheneverelectronsflowthroughaconductor,amagneticfieldwilldeveloparoundthatconductor.Thiseffectiscalledelectromagnetism.Magneticenergycanbestoredinamagneticfield.Thedevicetobecapableofdoingthisiscalledaninductor.11/7/202212通信与信息工程专业英语教程lTostoremoreenergyinaninductor,thecurrentthroughitmustbeincreased.Thismeansthatitsmagneticfieldmustincreaseinstrength,andthatchangeinfieldstrengthproducesthecorrespondingvoltageaccordingtotheprincipleofelectromagneticself-induction.Whenthecurrentthroughaninductorisincreased,itdropsavoltageopposingthedirectionofelectronflow,actingasapowerload.Inthisconditiontheinductorissaidtobecharging,becausethereisanincreasingamountofenergybeingstoredinitsmagneticfield.Notethepolarityofthevoltagewithr