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1、Chapter1CircuitElementsandCircuitLawsEmphases：Referencedirectionofvoltage,currentandelectromotiveforce2.Characteristicofcircuitelement3.Kirchhoff’sLaws1.1ConstituteofCircuit1.Constituteofcircuit+i-VSourceloadSource:generatororbatteryLoad:electriclight,motororstoveMiddlej
2、oint:switchorwire2.CircuitandCircuitModelPracticalcircuit:Circuitmodel:导线开关电池灯泡+R0R开关E干电池电珠Swireswitchbattery+R0RswitchEbatteryLightSI_+Rcircuitmodel:idealcircuitelementcomposedswitchbatterylight+_UEPracticalcircuit1.2Referencedirectionofvoltageandcurrent1.Currentdefine:
3、thetimerateofchangeofchargepassingthroughapredeterminedarea.Value:i=dq/dt(AC)I=q/t(DC)Direction:unit:A,mA,AabSIabReferencedirections(1)Referencedirectionsforcurrent(2)ReferencedirectionsforvoltageReferencedirection:oftendefinedirectionofpositiveelectriccharge(oropposite
4、directionofnegativecharge).Sometimesfactualdirectionisunknownbeforeanalysisinsomecircuit;directionofalternatingcurrentalwayschange,itsdirectionofcurrentisuncertain.Referencedirection:anydirectionofcurrentissupposedbeforeanalysisinsomecircuit.Ifdirectionbetweenreferencedi
5、rectionandfactualdirectionissame,valueofcurrentispositive;ornot,itsvalueisnegative.ReferencedirectionofcurrentDirection：Actioninelectricfield,positiveelectricchargesmovefromhigherpotentialtolowerpotential.Referencedirection:definemovedirectionofpositiveelectriccharge.Bef
6、oreanalysisinelectriccircuit,chooseanydirectionasreferencedirectionofvoltage.Ifdirectionbetweenreferencedirectionandfactualdirectionissame,valueofvoltageispositive;ornot,itsvalueisnegative.Unit：V,kV,mV2.VoltageInfigurerelativedirectionvoltageandcurrentRelativedirectionab
7、IUabIUReferenceconventionsfortwo-terminalelements(R,L,Cor...)Ohm'slawstatesthatvoltageacrossmanytypesofconductingmaterialsisdirectlyproportionaltothecurrentflowingthroughthematerial.Expression:IfR=constant,wecalledRlinearresistance.Ohm’lawisappliedinsimplecircuit.UIR3.Oh
8、m’sLawDefinesymbolinOhm’slaw:IfreferencedirectionincurrentandvoltageisrelativedirectionUIROhm’slawIfref
