Chapter09

Chapter 9, Problem 56.

At ω = 377 rad/s, find the input impedance of the circuit shown in Fig. 9.63.

Figure 9.63

For Prob. 9.56.

Chapter 9, Problem 57.

At ω = 1 rad/s, obtain the input admittance in the circuit of Fig. 9.64.

Figure 9.64

For Prob. 9.57.

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Chapter 9, Problem 58.

Find the equivalent impedance in Fig. 9.65 at ω = 10 krad/s.

Figure 9.65

For Prob. 9.58.

Chapter 9, Problem 59.

For the network in Fig. 9.66, find Z in . Let ω = 10 rad/s.

Figure 9.66

For Prob. 9.59.

Zin = j5 (5 − j0.4) = (5 90°)(5.016 −4.57°) = 3.691 42.82°

6.794 42.61°

= 2.707+j2.509 Ω.

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Chapter 9, Problem 60.

Obtain Z in for the circuit in Fig. 9.67.

Figure 9.67

For Prob. 9.60.

Chapter 9, Solution 60.

Z = (25 + j15) +(20 − j50) //(30 + j10) = 25 + j15 + 26.097 − j5.122 = 51.1+ j9.878Ω

Chapter 9, Problem 61.

Find Z eq in the circuit of Fig. 9.68.

Figure 9.68

For Prob. 9.61.

Chapter 9, Solution 61.

All of the impedances are in parallel.

1

Zeq = 0.8 − j0.4 = 1 + j0.5 Ω

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Chapter 9, Problem 62.

For the circuit in Fig. 9.69, find the input impedance Z in at 10 krad/s.

Figure 9.69

For Prob. 9.62.

Chapter 9, Solution 62.

-j100 Ω

V = (1 0°)(50) = 50

Vin = (1 0°)(50 + j20 − j100) +(2)(50)

Vin = 50 − j80 +100 =150 − j80

Zin = 1Vin0° = 150 – j80 Ω

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Chapter 9, Problem 63.

For the circuit in Fig. 9.70, find the value of Z T .

Figure 9.70

For Prob. 9.63.

Chapter 9, Solution 63.

First, replace the wye composed of the 20-ohm, 10-ohm, and j15-ohm impedances with the corresponding delta.

Now all we need to do is to combine impedances.

z3 (10 − j16) = 21.70 − j3.821

ZT = 8 − j12 + z1(8.721− j8.938 + 21.7 − j3.821) = 34.69 − j6.93Ω

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Chapter 9, Problem 64.

Find ZT and I in the circuit of Fig. 9.71.

Figure 9.71

For Prob. 9.64.

Chapter 9, Solution 64.

I = 30 90° = −0.3866 + j1.4767 =1.527 104.7°A

ZT

Chapter 9, Problem 65.

Determine Z T and I for the circuit in Fig. 9.72.

Figure 9.72

For Prob. 9.65.

Chapter 9, Solution 65.

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Chapter 9, Problem 66.

For the circuit in Fig. 9.73, calculate Z T and V ab .

Figure 9.73

For Prob. 9.66.

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Chapter 9, Solution 66.

+ Vab −

I1 = 4060++j10j5 I = 128 ++j2j I

I2 = 6020 +− jj55 I = 124 −+jj I

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Chapter 9, Problem 67.

At ω = 10 3 rad/s find the input admittance of each of the circuits in Fig. 9.74.

Figure 9.74

For Prob. 9.67.

Chapter 9, Solution 67.

Zin = 63.33 + j23.33 = 67.494 20.22°

1

Yin = Zin = 14.8 -20.22° mS

30 || 60 = 20

1

Yin = Zin = 19.7 74.56° mS = 5.24 + j18.99 mS

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Chapter 9, Problem 68.

Determine Y eq for the circuit in Fig. 9.75.

Figure 9.75

For Prob. 9.68.

Chapter 9, Solution 68.

Yeq = 5 −1 j2 + 3 1+ j + -1j4

Yeq = (0.1724 + j0.069) +(0.3 − j0.1) +( j0.25)

Yeq = 0.4724 + j0.219 S

PROPRIETARY MATERIAL. © 2007 The McGraw-Hill Companies, Inc. All rights reserved. No part of this Manual may be displayed, reproduced or distributed in any form or by any means, without the prior written permission of the publisher, or used beyond the limited distribution to teachers and educators permitted by McGraw-Hill for their individual course preparation. If you are a student using this Manual, you are using it without permission.