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1、Solvethefollowingproblems.(100points)1>(6points)FindJ7abinthecircuitinFigureL*bFigure1Solution:uah=9V2>(8points)Findu0andi()inthecircuitinFigure2.+Figure2Solution:uo=2.4V■io=-0.256mA3、(6points)InthecircuitofFigure3,readingsofvoltmeter©,©and@are10V,18Van
2、d6V,respectively.Pleasedeterminatethereadingofthevoltmeter©.Figure3Solution:Thereadingofthevoltmeteris10V.4>(8points)TheresonantortunercircuitofaradioisportrayedinFigure4,wherewsirepresentsabroadcastsignal,giventhat7?=10f2,L=200jiH,Sirms=l・5mV,/i=1008kH
3、z>Ifthecircuitisresonantwithsignalusi,pleasedeterminate:(1)thevalueofC;(2)thequalityfactorQofthecircuit;(3)thecurrentInns;(4)thevoltageU^.OFigure4Solution:(1)C«12.5pF(2)0«126.6(3"如=150"(4)UCnns=190mV5*(8points)Abalancedthree-phasecircuitisshowninFigure5
4、.Calculatethephasecurrentsandvoltagesinthedelta-connectedloadZ,ifUA=220Z0°V,Z=(24+jl5)Q,ZL=(l+jl)n・figure5:Solution:Ia^=11・74Z-3・69°A,U;®=332Z28・31°V6、(8points)FindthejparametersforthecircuitinFigure6-Pigure6Solution:[小0.240.020.57>(15points)Forthecircu
5、itinfigure7,findthermsvalueofthecurrentiandtheaveragepowerabsorbedbythecircuit,giventhata)L=10£l,R、=5Q,/?2=20J1,1/coC=20Q,叫(/)=80+100cos6X+50cos(2d^+30°)V・Figure7Solution:Irms=++=a/3.224-4.7142+2.3572=6.17AP=Po+Pi+P2=256+333・28+5O=639・28W8、(12points)Int
6、hecircuitofFigure&determinatethevalueofZthatwillabsorbthemaximumpowerandcalculatethevalueofthemaximumpower50Z0°Vrmsco-103rad/sFigureSSolution:5+213Q,Zwillabsorbthemaximumaveragepower.Themaximumaveragepoweris,UqcReq119.6245/13=249.7W9>(14points)Iftheswit
7、chinFigure9hasbeenclosedforalongtimeandisopenedatZ=0,finduC9応"kfort>0.Figure9Solution:匚=l・5+(0-1・5)严=1・5-1・5严人Z>0,uc=120+(60-120)e"。=i20_6O严2°V,f>0t>0uK=20iL-uc=—90—30严+600"V10、(15points)TheswitchinFigure10hasbeeninpositionaforalongtime.At/=0,itmovestop
8、ositionb.Findi2(t)forfN0andsketchit(Attention:Pleasemarkthekeydatainyourgraph.)Figure10Solution:i2=1.25e_/-l・25e"A