《电路》（英文版）Chpter 8 Problems

Basic Circuit Theory Chpter8 Problems I(a)Find V, in Fig. 8-20.(b)To what identical value should each of the 4Q2 resistors be changed so that V2 is 180 out of phase with the source voltage? 4 -j49+-j49+-j492 Fig 8-20 For prob. I 2 Find v3(t)in the circuit of Fig 8-21 by using nodal analysis 400uF √2 0130100n2" Fig 8-21 For prob. 2 3(a) Find i,(t)in the circuit of Fig 8-22.(b) Change the control voltage from 3v, to 3v, and again find i2(t) +[102cos 10tA 31 Imh Fig 8-22 For prob. 3 4 For the circuit of Fig 8-23 find v r(t) and v(t) F 106tA VLR2uH Fig 8-23 For prob. 4 5(a) Find the Thevenin equivalent of the network shown in Fig. 8-24a (b) Find the Norton equivalent of the network shown in Fig. 8-24b 0.oluF ①1v 0.2H 10kg2 104tA DaLian Maritime University

Basic Circuit Theory Chpter8 Problems 1 (a) Find in Fig.8-20. (b) To what identical value should each of the 4Ω resistors be changed so that is 180 o out of phase with the source voltage? • V2 • V2 DaLian Maritime University 50 + - + - 2 • / 0°V V 4 Ω 4 Ω − j 4 Ω − j 4 Ω 4 Ω − j 4 Ω Fig. 8-20 For prob.1. 2 Find v 3 (t) in the circuit of Fig.8-21 by using nodal analysis. ( - + A 1Ω 2 Ω 3 v 400 µF 0.4mH 3 i 10 2 cos 10 30 ) 4 t + ° 1Ω 1Ω 3 (a) Find i 2 (t) in the circuit of Fig.8-22. (b) Change the control voltage from 3v1 to 3v and again find i 2 (t). 2 Fig. 8-21 For prob.2. + - 3 - + + - 2 v A 1 v 2 i 10 2 cos 1 v t 4 10 20Ω 4mH 1mH 2µF Fig. 8-22 For prob.3. 4 For the circuit of Fig.8-23 find v (t) and v (t). R L + + - - 2 Ω L v R v F 4 1 µ 2A 2 cos t 6 10 A 2µH 5 (a) Find the Thevenin equivalent of the network shown in Fig.8-24a. Fig. 8-23 For prob.4. (b) Find the Norton equivalent of the network shown in Fig.8-24b. + - (a) (b) Fig. 8-24 For prob.5. a b 0.2H 80Ω 2H 0.01µF 50 2 cos t 3 10 10 kΩ a b t 4 10 A V 20 2 cos 1

Basic Circuit Theory Chpter8 Problems 6 Find the output impedance of the network in Fig. 8-25 12gJ2092 Vr j39 7(a) Find the frequency-domain Norton equivalent of the network depicted in Fig. 8-26.(b) Give element values for one network that this norton equivalent(at =2000 rad/s) 0.5 200tA△20uF b Fig 8-26 For prob.7 8 Use superposition to find Ir in Fig. 8-27 10°A l0°V1∠Q。V ∠0°A 9 For the circuit of Fig 8-28 find the phase angle of the V and v graphically if k 90V and V,=150V D20V5080 Fig. 8-28 For prob. 9 10 Use phasors and nodal analysis on the circuit of Fig 8-29 to find V? A10∠Q°A 3Q 5/90 Fig. 8-29 For prob. 10. DaLian Maritime University

Basic Circuit Theory Chpter8 Problems 6 Find the output impedance of the network in Fig.8-25. + - 12 Ω 1 0.1 − j 3 Ω j 20 Ω 1 ' x v x v Fig. 8-25 For prob.6. 7 (a) Find the frequency-domain Norton equivalent of the network depicted in Fig.8-26. (b) Give element values for one network that this Norton equivalent (at ω =2000 rad/s). A a b i 20µF i 250Ω 200 t 20 2 cos 0 .5 8 Use superposition to find I x in Fig.8-27. • Fig. 8-26 For prob.7. - + - + 1 V / 0° − j1Ω 1Ω 1Ω j1Ω / 0°V / 0°A 1 1 1 I x • / 0°A 9 For the circuit of Fig.8-28 find the phase angle of the and graphically if = 90V and =150V. • Vx • Vy Vx Vy Fig. 8-27 For prob.8. + - + - - + - + 1 20/ 0°V V x • V y • 50 / 80°V 10 Use phasors and nodal analysis on the circuit of Fig.8-29 to find . • V2 Fig. 8-28 For prob.9. 3 Ω j 3 Ω − j5 Ω 6 Ω 2 • V I B • 5 / 90 ° A 10 / 0° A Fig. 8-29 For prob.10. DaLian Maritime University 2

Basic circuit the I Find vx(t)in the circuit of Fig 8-30 if v si=20cos1000t V and V$2=20sin1000t V Fig. 8-30 For prob. 1 sh analysis to find ir (t) in the circuit sho Fig 8-31 Fig. 8-31 For prob. 12 Reference answers to Selec b ot ed problems (a)781∠-1287V,(b)9.89 2:647√2cos(100044)V 3:(a)110√2cos(10001337°)A;(b)3.29√2cos(10001705 4:(a)-4+2cos(10°t45°)V(b)2cos10°t135°)V 5:(a)464√2cos(1000+21.8°)V;(b)179√2cos(1000164°)A 8:1.58∠-1843 10:344∠23.6 707cos(1000t-45°)V 0t-76.0°)A Dalian maritime universi

Basic Circuit Theory Chpter8 Problems 11 Find v X (t) in the circuit of Fig.8-30 if v =20cos1000t V and v =20sin1000t V. S1 S 2 + - + - 10mH 0.1mF s1 v 25Ω x v s 2 v Fig. 8-30 For prob.11. 12 Use mesh analysis to find i (t) in the circuit shown in Fig.8-31. X + - - + Fig. 8-31 For prob.12. x i 100t V 10cos 1Ω x v 1Ω 1Ω 0.04H 1Ω 0.04F Reference Answers to Selected Problems 1: (a) 7.81 V; (b) 9.8Ω . o ∠ −128.7 2: 6.47 2 cos(10000t+44 ) V. o 3: (a) 11.09 2 cos(10000t+33.7 ) A; (b) 3.29 o 2 cos(10000t+170.5 ) A. o 4: (a) –4+2 cos(10 t-45 ) V; (b) 2 cos(10 t+135 ) V. 6 o 6 o 5: (a) 46.4 2 cos(1000t+21.8 ) V; (b) 17.9 o 2 cos(10000t+63.4 ) A. o 7: (a) 15.8∠ −18.4 A, (1+j1) mS; (b) 1 mS, 0.5 o µ F. 8: 1.58∠ −18.43 . o 9: 65 and -61 , or -113 o and 13 . o o o 10: 34.4∠23.6 V. o 11: 70.7 cos(1000t-45 ) V. o 12: 1.213 cos(100t-76.0 ) A. o DaLian Maritime University 3