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1、Solvethefollowingproblems.(100points)
1、(6points)FindUabinthecircuitinFigure1.
3k Q
2k Q
0.5I
+
2、ereadingofthevoltmeter(V.
Figure 3
4、 ( 8 points) The resonant or tuner circuit of a radio is portrayed in Figure 4, where us1 represents a broadcast signal, given that R=10Q , L=200pH, Us1rms=1.5mV, f1=1008kHz. If the circuit is resonant with signal us1, please determinate: (1) the value of C; (2
3、) the quality factor Q of the circuit; (3) the current Irms; (4) the voltage Ucrms.
i
R
Figure 4
5、(8points)Abalancedthree-phasecircuitisshowninFigure5.Calculatethe?
phasecurrentsandvoltagesinthedelta-connectedloadZ,ifUA=220/0V,
Z=(24+j15)Q,ZL=(1+j1)Q
Figure 5
6、( 8 points) Find the y p
4、arameters for the circuit in Figure 6.
Figure 6
7、(15points)Forthecircuitinfigure7,findthermsvalueofthecurrentiandtheaveragepowerabsorbedbythecircuit,giventhatL=10Q,
R1=5Q,R2=20Q,1/^C=20Q,us(t)=80+100cosot+50cos(2?t+300)V.
8、(12points)InthecircuitofFigure8,determinatethevalueofZthatwill
5、absorbthemaximumpowerandcalculatethevalueofthemaximumpower.
+2Ii
l
4Q
Ii
50.0Vrms
co
=103rad/s
Figure8
9、(14points)IftheswitchinFigure9hasbeenclosedforalongtimeandisopenedatt=0,finduc,iL,ukfort>0.
Figure 9
10、(15points)TheswitchinFigure10hasbeeninpositionaforalongtime.Att=0,
6、itmovestopositionb.Findi2(t)fort>0andsketchit.(Attention:Pleasemarkthekeydatainyourgraph.)
60V
3Q
10Q
Figure 10
Solvethefollowingproblems.(100points)
1、(6points)FindUabinthecircuitinFigure1.
Figure1
Solution:
Uab=9V
2、(8points)Findu。andiointhecircuitinFigure2.
1V
+
uo
Figure 2
7、
Solution:
uo-2.4V,io=—0.256mA
3、(6points)InthecircuitofFigure3,readingsofvoltmeter(V1;,(V2)and(V3are10V,18Vand6V,respectively.Pleasedeterminatethereadingofthe
Figure3
Solution:
Thereadingofthevoltmeter(Vis10V.
4、 (8points)TheresonantortunercircuitofaradioisportrayedinFigure4,whereusir
8、epresentsabroadcastsignal,giventhatR=10Q,L=200pH,Us1rms=1.5mV,f1=1008kHz.Ifthecircuitisresonantwithsignalusi,pleasedeterminate:(1)thevalueofC;(2)thequalityfactorQofthecircuit;(3)thecurrentIrms;(4)thevoltageUcrms.
Solution:
(1)C：12.5pF(2)Q：126.6(3)1rms=150然A(4)UCrms=190mV
5、(8points)Abalance
9、dthree-phasecircuitisshowninFigure5.Calculatethe?
phasecurrentsandvoltagesinthedelta-connectedloadZ,ifUA=2200V,
Z=(24+j15)Q,ZL=(1+j1)Q
Solution:
IA,B'=11.74-3.69A,
UA舊,=33228.31V
6、(8points)FindtheyparametersforthecircuitinFigure6.
I
+
5 O
U?1 0.1U2(>
Figure 6
Solution:
10、lyl =
0.20.02
S
?0.51
7、(15points)Forthecircuitinfigure7,findthermsvalueofthecurrentiandtheaveragepowerabsorbedbythecircuit,giventhat■L=10Q,
Ri=5Q,R2=20Q,1/bC=20Q,us(t)=80+100coscot+50cos(2cot+30口)V.
R2
Figure 7
Solution:
Irms-I21l2I；='；3.224.71422.3572-6.17A
P=P0+Pi+P2=256+333.28+50
11、=639.28W
8、 (12points)InthecircuitofFigure8,determinatethevalueofZthatwillabsorbthemaximumpowerandcalculatethevalueofthemaximumpower.
Solution:
5，j
Ifz=Zeq=——-q,Zwillabsorbthemaximumaveragepower.13
1Uoc119.62
Themaximumaveragepoweris,Pmax=—^C=—=249.7W
4Req4513
9、 (14points)IftheswitchinFig
12、ure9hasbeenclosedforalongtimeandisopenedatt=0,finduc,iL,ukfort>0.
+
uc
Figure 9
Solution:
__40t_40t_
iL=1.5+(0—1.5)e=1.5—1.5eA,t>0,
uC=120(60—120)e'/20=120—60e,/2°V,t0
uK=20iL-uC=-90-30e'0t60e,/20V,t0
10、(15points)TheswitchinFigure10hasbeeninpositionaforalongtime.Att=0,itmovestopositionb.Findi2(t)fort>0andsketchit.(Attention:Pleasemarkthekeydatainyourgraph.)
60V
10Q
Figure 10
Solution：i2=1.25e"-1.25e*tA
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東南大學(xué)電子學(xué)院《電路基礎(chǔ)》期末考試樣卷及答案
