电子与通信技术专业英语Unit-I-3课件

Unit Basic Knowledge of ElectronicsLesson 3 AC,DC and Electrical SignalsUnitBasicKnowledgeNew Words positivepztiva.正的frequencyfrikwnsin.频率measuremev.n测量devicedivaisn.装置，设备labelleibln.标签v.贴标签于；NewWordsamplitudemplitju:dn.振幅periodprdn.时期，周期oscilloscopesiluskupn.示波器millisecondmili,sekndn.毫秒microsecondmili,sekndn.微秒电子与通信技术专业英语Unit-I-3课件Phrases and ExpressionsAlternatingCurrent交流电DirectCurrent直流电powersupply电源electroniccircuit电子电路PhrasesandExpressionselectricalsignal电信号peakvoltage峰值电压peak-peakvoltage峰-峰值电压effectivevalue有效值electricalsignalNotes1.TherateofchangingdirectioniscalledthefrequencyoftheACanditismeasuredinhertz(Hz)whichisthenumberofforwards-backwardscyclespersecond.hertz(Hz)：n.赫兹(电学频率单位)；赫(兹),每秒周数频率单位【大写】赫兹(德国物理学家)n.赫兹(电学频率单位)；【大写】赫兹(德国物理学家)cyclespersecond：每秒循环数这种方向变化的速率称为交流信号的频率，单位是赫兹，它表示一秒内周期性变化的次数。Notes2.Thevoltage-timegraphonthefig.3-4showsvariouspropertiesofanelectricalsignal.voltage-timegraph：电压时间曲线图34的电压时间图显示了一个电信号的各种特性。2.Thevoltage-timegraphonth3.Thediagramshowsasinewavebutthesepropertiesapplytoanysignalwithaconstantshape.sinewave：n.正弦波cosinewave：n.余弦波该图显示了一个正弦波，但这些特性适用于具有恒定形状的任何信号。3.Thediagramshowsasinewav4.Timeperiodisthetimetakenforthesignaltocompleteonecycle.Itismeasuredinseconds(s),buttimeperiodstendtobeshortsomilliseconds(ms)andmicroseconds(s)areoftenused.1ms=0.001sand1s=0.000001s.milliseconds(ms)：n.毫秒；微秒microseconds(s)：micro-secondn：微秒周期是完成一个周期的信号所需要的时间。单位是秒，但是周期往往非常短，所以常用毫秒（ms）和微秒(s)。1ms=0.001s，1s=0.000001s。4.Timeperiodisthetimetak5.1kHz=1000Hzand1MHz=1000000Hz.千赫（kHz）和兆赫（MHz）。5.1kHz=1000Hzand1MHz=106.Frequency1/timeperiodandtimeperiod=1/frequency.timeperiod：周期频率1/周期，周期1/频率6.Frequency1/timeperiodanTranslationofTextsLesson 3 AC,DC and Electrical Signals Alternating Current(AC)AlternatingCurrent(AC)flowsoneway,thentheotherway,continuallyreversingdirection.AnACvoltageiscontinuallychangingbetweenpositive(+)andnegative(-).TherateofchangingdirectioniscalledthefrequencyoftheACanditismeasuredinhertz(Hz)whichisthenumberofforwards-backwardscyclespersecond.TranslationofTextsLesson3第第3课课 交流电，直流电以及电信号交流电，直流电以及电信号 交流电交流电交流电流的方向从一个方向转换成另一个方向，持续不断的转换（如图31和图32所示）。交流电压会持续不断的在正负两个极性之间交替变化。这种方向变化的速率称为交流信号的频率，单位是赫兹，它表示一秒内周期性变化的次数。第3课交流电，直流电以及电信号AnACsupplyissuitableforpoweringsomedevicessuchaslampsandheatersbutalmostallelectroniccircuitsrequireasteadyDCsupply.交流电源适用于给一些设备供电，如灯和加热器，但几乎所有的电子电路都需要一个稳定的直流电。AnACsupplyissuita Direct Current(DC)DirectCurrent(DC)alwaysflowsinthesamedirection,butitmayincreaseanddecrease.ADCvoltageisalwayspositive(oralwaysnegative),butitmayincreaseanddecrease.ElectroniccircuitsnormallyrequireasteadyDCsupplywhichisconstantatonevalue.Cells,batteriesandregulatedpowersuppliesprovidesteadyDCwhichisidealforelectroniccircuits.Lamps,heatersandmotorswillworkwithanyDCsupply.DirectCurrent(DC)直流电直流电直流电流总是向同一个方向流动，但它可能增大或者减小。直流电的方向总是正的（或者总是负的），但它也可能增大或者减小（如图33所示）。电子电路通常需要一个具有定值的稳定的直流电源。干电池、蓄电池（组）和稳压电源能提供对于电子电路来说理想的、稳定的直流电。在直流电源作用下，电灯，加热器和发动机将可以正常工作。直流电 Properties of electrical signalsAnelectricalsignalisavoltageorcurrentwhichconveysinformation,usuallyitmeansavoltage.Thetermcanbeusedforanyvoltageorcurrentinacircuit.电信号的特性电信号的特性电信号是传送信息的电压或者电流，通常是指电压。这个术语可以被用于电路里任何一个电压或者电流。PropertiesofelectThevoltage-timegraphonthefig.3-4showsvariouspropertiesofanelectricalsignal.Inadditiontothepropertieslabeledonthegraph,thereisfrequencywhichisthenumberofcyclespersecond.Thediagramshowsasinewavebutthesepropertiesapplytoanysignalwithaconstantshape.Thevoltage-timegra图34的电压时间图显示了一个电信号的各种特性。除了图上标明的那些特性以外还有频率，它表示每秒钟的周期数。该图显示了一个正弦波，但这些特性适用于具有恒定形状的任何信号。图34的电压时间图显示了一个电信号的Amplitudeisthemaximumvoltagereachedbythesignal.Itismeasuredinvolts,V.振幅是信号所达到的最大电压。单位是伏特，V。AmplitudeisthemaxPeakvoltageisanothernameforamplitude.峰值电压是振幅的另一个名称。PeakvoltageisanothPeak-peakvoltageistwicethepeakvoltage(amplitude).Whenreadinganoscilloscopetraceitisusualtomeasurepeak-peakvoltage.峰峰值电压是峰值电压（振幅）的两倍。当对示波器上的轨迹进行读数的时候，我们通常测量峰峰值电压。Peak-peakvoltageisTimeperiodisthetimetakenforthesignaltocompleteonecycle.Itismeasuredinseconds(s),buttimeperiodstendtobeshortsomilliseconds(ms)andmicroseconds(s)areoftenused.1ms=0.001sand1s=0.000001s.周期是完成一个周期的信号所需要的时间，单位是秒。但是周期往往非常短，所以常用毫秒（ms）和微秒(s)。1ms=0.001s，1s=0.000001s。TimeperiodisthetFrequencyisthenumberofcyclespersecond.Itismeasuredinhertz(Hz),butfrequenciestendtobehighsokilohertz(kHz)andmegahertz(MHz)areoftenused.1kHz=1000Hzand1MHz=1000000Hz.1kHz=1000Hzand1MHz=1000000Hz。Frequency1/timeperiodandtimeperiod=1/frequency.Frequencyisthenumb频率是每秒的周期数。单位是赫兹（Hz），但频率往往比较高，所以常用千赫（kHz）和兆赫（MHz）。频率1/周期，周期1/频率。频率是每秒的周期数。单位是赫兹（Hz），但AnothervalueusedistheeffectivevalueofAC.Thisisthevalueofalternatingvoltageorcurrentthatwillhavethesameeffectonaresistanceasacomparablevalueofdirectvoltageorcurrentwillhaveonthesameresistance.Anothervalueusedi另一个常用的值是有效值，电压或电流有效值作用于电阻，与相同大小的直流电压或电流作用于相同大小的电阻等效。另一个常用的值是有效值，电压或电流有效值Exercises.Write T(True)or F(false)beside the following statements about the text.Exercises1.DirectCurrent(DC)flowsoneway,thentheotherway,continuallyreversingdirection.1.DirectCurrent(DC)flowson2.AlternatingCurrent(AC)alwaysflowsinthesamedirection.2.AlternatingCurrent(AC)alw3.Amplitudeistheminimumvoltagereachedbythesignal.3.Amplitudeistheminimumvol4.Peak-peakvoltageistwicethepeakvoltage(amplitude).4.Peak-peakvoltageistwicet5.TheeffectivevalueofACisthevalueofalternatingvoltageorcurrentthatwillhavethesameeffectonaresistanceasacomparablevalueofdirectvoltageorcurrentwillhaveonthesameresistance.5.TheeffectivevalueofACis.Fill in the missing words according to the text.Fillinthemissingwordsa1.AnACvoltageiscontinuallychangingbetweenand.1.AnACvoltageiscontinually2.ElectroniccircuitsnormallyrequireasteadyDCsupplywhichisonevalue.2.Electroniccircuitsnormally3.Cells,batteriesandregulatedpowersuppliesprovidewhichisidealforelectroniccircuits.3.Cells,batteriesandregulat4.Inadditiontothepropertieslabeledonthegraph,thereisfrequencywhichisthenumberofpersecond.4.Inadditiontothepropertie5.Whenreadinganoscilloscopetraceitisusualtomeasurevoltage.5.Whenreadinganoscilloscope.Match the following terms to appropriate definition or expression.Matchthefollowingtermst1.Anelectricalsignal1/timeperiod2.Peakvoltagethemaximumvoltagereachedbythesignal3.Peak-peakvoltagetwicethepeakvoltage(amplitude)4.Frequencyavoltageorcurrentwhichconveysinformation1.Anelectricalsignal1/EndEnd