电子与通信工程专业英语 教学课件 作者 徐存善 Unit 6.ppt

《电子与通信工程专业英语 教学课件 作者 徐存善 Unit 6.ppt》由会员上传分享，免费在线阅读，更多相关内容在教育资源-天天文库。

1、Unit6LinearCircuitAnalysisTranslationReadingmoreTranslatingskillsTextLinearCircuitAnalysis电子与通信工程专业英语电子与通信工程专业英语LinearCircuitAnalysisGustavRobertKirchhoffKVLKCLGeorgSimonOhm欧姆.G.S.R=Ohm’sLaw1．Ohm’sLawSupposethatsomematerialisconnectedtotheterminalsofanidealvoltagesourceu(t)asshowninFig6-1．

2、Supposethatu(t)=1V,thentheelectricpotentialatthetopofthematerialis1Vabovethepotentialatthebottom．Sinceanelectronhasanegativecharge,electronsinthematerialwilltendtoflowfrombottomtotop．Therefore，wesaythatacurrenttendstogofromtoptobottomthroughthematerial.Hence,forthegivenpolarity,whenu(t)isa

3、positivenumber,i(t)willbeapositivenumberwiththedirectionindicatedinFig6-1.第6单元线性电路分析1．欧姆定律假若把某种材料连接到一个理想电压源u(t)的两端(如图6-1所示)，设u(t)=1V，则材料顶部的电势(电位)比材料底部的电势高出1V，由于电子是携带负电荷的，在材料中的电子将从材料的底部流向顶部，即有电流i(t)从材料的顶部通过材料流向底部。因此，当电源极性给定时，当u(t)为正时，电流正方向如图6-1所示。电子与通信工程专业英语Ifu(t)=2V,againthepotentialatthet

4、opisgreater2Vthanatthebottom，soi(t)willagainbepositive.However，becausethepotentialisnowtwiceaslargeasbefore，thecurrenti(t)begreater(Ifthematerialisa“linear”element，thecurrentwillbetwiceasgreat)．Iftheresultingcurrenti(t)isalwaysdirectlyproportionaltothevoltageforanyfunctionu(t)，themateriali

5、scalledalinearresistor．Toalinearresistor，wehave：R=andi(t)=Theunitofresistance(voltsperampere)isreferredtoasOhmsandisdenotedbythecapitalGreekletteromega．BothequationsabovearealsoreferredtoasOhm’slaw．假若u(t)=2V，同理，材料顶部的电势(电位)比材料底部的电势高出2V，所以电流i(t)仍为正的(当材料为“线性”材料时，电流是原来的两倍)。对任意给定的电压函数u(t)，假若产生的

6、电流总是与给定的电压函数u(t)成正比，则该材料被称为线性电阻。一个线性电阻有：R=和i(t)=电阻的单位(伏特每安培)叫欧姆，且用大写希腊字母“”表示，上面的两个方程均称为欧姆定律。电子与通信工程专业英语2．Kirchhoff’sCurrentLawItisaconsequenceoftheworkoftheGermanphysicist(1824-1887)thatenablesustoanalyzeaninterconnectionofanynumberofelements(voltagesources，currentsources，andresistors),asw

7、ellasotherelectronicdevices．Wewillrefertoanysuchinterconnectionasacircuitoranetwork．Foragivencircuitaconnectionoftwoormoreelementsshallbecalledanode.WenowpresentthefirstofKirchhoff’stwolaws，hiscurrentlaw(KCL)，whichisessentiallythelawofconservationofelectriccha