或展示章电压现行两个网络等效这三个节点五个分支路径序列循环封闭圆形ch3 voltage and current laws.pptx

Copyright?2013TheMcGraw-HillCompanies,Inc.Permissionrequiredforreproductionordisplay.1Chapter3VoltageandCurrentLaws

Nodes,Paths,Loops,BranchesCopyright?2013TheMcGraw-HillCompanies,Inc.Permissionrequiredforreproductionordisplay.2thesetwonetworksareequivalenttherearethreenodesandfivebranchesapathisasequenceofnodesaloopisaclosed(circular)path

Kirchhoff’sCurrentLawKCL:Thealgebraicsumofthecurrentsenteringanynodeiszero.Copyright?2013TheMcGraw-HillCompanies,Inc.Permissionrequiredforreproductionordisplay.3iA+iB+(?iC)+(?iD)=0

KCL:AlternativeFormsCurrentINiszero:iA+iB+(?iC)+(?iD)=0CurrentOUTiszero:(-iA)+(-iB)+iC+iD=0CurrentIN=OUT:iA+iB=iC+iDCopyright?2013TheMcGraw-HillCompanies,Inc.Permissionrequiredforreproductionordisplay.4

ExampleofKCLApplicationCopyright?2013TheMcGraw-HillCompanies,Inc.Permissionrequiredforreproductionordisplay.5FindthecurrentthroughresistorR3ifitisknownthatthevoltagesourcesuppliesacurrentof3A.Answer:i=6A

Kirchhoff’sVoltageLawCopyright?2013TheMcGraw-HillCompanies,Inc.Permissionrequiredforreproductionordisplay.6KVL:Thealgebraicsumofthevoltagesaroundanyclosedpathiszero.v1+(-v2)+(?v3)=0

KVL:AlternativeFormsCopyright?2013TheMcGraw-HillCompanies,Inc.Permissionrequiredforreproductionordisplay.7SumofRISESiszero(clockwisefromB):v1+(-v2)+v3=0SumofDROPSiszero(clockwisefromB):(-v1)+v2+(-v3)=0Twopaths,samevoltage(AtoB):v1=(-v3)+v2

Example:ApplyingKVLCopyright?2013TheMcGraw-HillCompanies,Inc.Permissionrequiredforreproductionordisplay.8FindvR2(thevoltageacrossR2)andthevoltagevx.Answer:vR2=32Vandvx=6V.

ApplyingKVL,KCL,Ohm’sCopyright?2013TheMcGraw-HillCompanies,Inc.Permissionrequiredforreproductionordisplay.9Example:findthecurrentixandthevol