Solucionario Capitulo 16 Sadiku

88
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. Chapter 16, Problem 1. Determine i(t) in the circuit of Fig. 16.35 by means of the Laplace transform. Figure 16.35 For Prob. 16.1. Chapter 16, Solution 1. Consider the s-domain form of the circuit which is shown below. 2 2 2 ) 2 3 ( ) 2 1 s ( 1 1 s s 1 s 1 s 1 s 1 ) s ( I + + = + + = + + = = t 2 3 sin e 3 2 ) t ( i 2 t - = ) t ( i A ) t 866 . 0 ( sin e 155 . 1 -0.5t 1/s 1 + 1/s s I(s)

Transcript of Solucionario Capitulo 16 Sadiku

Page 1: Solucionario Capitulo 16 Sadiku

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.

Chapter 16, Problem 1. Determine i(t) in the circuit of Fig. 16.35 by means of the Laplace transform.

Figure 16.35 For Prob. 16.1. Chapter 16, Solution 1. Consider the s-domain form of the circuit which is shown below.

222 )23()21s(1

1ss1

s1s1s1

)s(I++

=++

=++

=

⎟⎟⎠

⎞⎜⎜⎝

⎛= t

23sine

32)t(i 2t-

=)t(i A)t866.0(sine155.1 -0.5t

1/s

1

+ −

1/s

s

I(s)

Page 2: Solucionario Capitulo 16 Sadiku

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Chapter 16, Problem 2. Find v x in the circuit shown in Fig. 16.36 given v s .= 4u(t)V.

Figure 16.36 For Prob. 16.2.

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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.

Chapter 16, Solution 2.

V)t(u)e2e24(v

38j

34s

125.0

38j

34s

125.0s25.016

)8s8s3(s2s16V

s32s16)8s8s3(V

0VsV)s4s2(s

)32s16()8s4(V

0

s84

0V2

0Vs

s4V

t)9428.0j3333.1(t)9428.0j3333.1(x

2x

2x

x2

x2

x

xxx

−−+− ++−=

⎟⎟⎟⎟

⎜⎜⎜⎜

−+

−+

++

−+−=

++

+−=

+=++

=++++

−+

=+

−+

−+

vx = Vt3

22sine2

6t3

22cose)t(u4 3/t43/t4⎟⎟⎠

⎞⎜⎜⎝

⎛−⎟⎟

⎞⎜⎜⎝

⎛− −−

4 +

Vx

s 8/s

s4

+ − 2

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Chapter 16, Problem 3. Find i(t) for t > 0 for the circuit in Fig. 16.37. Assume i s = 4u(t) + 2δ (t)mA. (Hint: Can we use superposition to help solve this problem?)

Figure 16.37 For Prob. 16.3.

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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.

Chapter 16, Solution 3. In the s-domain, the circuit becomes that shown below. 1 I 4 2s+

2 0.2s We transform the current source to a voltage source and obtain the circuit shown below. 2 1 I 8 4s+

0.2s

8 4 20 403 0.2 ( 15) 15

s A BsIs s s s s

+ += = = +

+ + +

40 8 15 20 40 52,15 3 15 3

xA B − += = = =

8 / 3 52 / 315

Is s

= ++

158 52( ) ( )3 3

ti t e u t−⎡ ⎤= +⎢ ⎥⎣ ⎦

+ _

Page 6: Solucionario Capitulo 16 Sadiku

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.

Chapter 16, Problem 4. The capacitor in the circuit of Fig. 16.38 is initially uncharged. Find v 0 (t) for t > 0.

Figure 16.38 For Prob. 16.4.

Chapter 16, Solution 4. The circuit in the s-domain is shown below. I 2 4I + 5 Vo 1/s 1 –

4 51/

oo

VI I I sVs

+ = ⎯⎯→ =

But 52

oVI −=

5 12.552 5 / 2

oo o

V sV Vs

−⎛ ⎞ = ⎯⎯→ =⎜ ⎟ +⎝ ⎠

2.5( ) 12.5 Vt

ov t e−=

+ _

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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.

Chapter 16, Problem 5.

If i s (t) = e t2− u(t) A in the circuit shown in Fig. 16.39, find the value of i 0 (t).

Figure 16.39 For Prob. 16.5. Chapter 16, Solution 5.

( )

( ) A)t(ut3229.1sin7559.0e

or

A)t(ueee3779.0eee3779.0e)t(i

3229.1j5.0s)646.2j)(3229.1j5.1(

)3229.1j5.0(

3229.1j5.0s)646.2j)(3229.1j5.1(

)3229.1j5.0(

2s1

)3229.1j5.0s)(3229.1j5.0s)(2s(s

2VsI

)3229.1j5.0s)(3229.1j5.0s)(2s(s2

2sss2

2s1

2s

21

s1

12s

1V

t2

t3229.1j2/t90t3229.1j2/t90t2o

22

2o

2

−=

++=

−+++

+−

+++

−−−−

++

=

−++++==

−++++=⎟⎟

⎞⎜⎜⎝

+++=

⎟⎟⎟⎟

⎜⎜⎜⎜

+++=

−°−−°−−

or io(t) = A)t(ut27sin

72e t2

⎟⎟⎠

⎞⎜⎜⎝

⎛⎟⎟⎠

⎞⎜⎜⎝

⎛−−

s s2

2s1+

Io

2

Page 8: Solucionario Capitulo 16 Sadiku

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Chapter 16, Problem 6. Find v(t), t > 0 in the circuit of Fig. 16.40. Let v s = 20 V.

Figure 16.40 For Prob. 16.6.

Chapter 16, Solution 6. For t<0, v(0) = vs = 20 V For t>0, the circuit in the s-domain is as shown below.

10s

1 10100 0.1mF FsC s

= ⎯⎯→ =

20 2

10 110sI

ss= =

++

20101

V Is

= =+

( ) 20 ( )tv t e u t−=

+ _

+

_ 10 Ω v

20s

I

Page 9: Solucionario Capitulo 16 Sadiku

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.

Chapter 16, Problem 7. Find v 0 (t), for all t > 0, in the circuit of Fig. 16.41.

Figure 16.41 For Prob. 16.7.

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Chapter 16, Solution 7. The circuit in the s-domain is shown below. Please note, iL(0) = 0 and vo(0) = o because both sources were equal to zero for all t<0. 1 1 Vo

2/s s 2/s 1/s At node 1

11 11

2 / 2 (2 1/ )1 1

oo

V Vs V V V s Vs s

−−= + ⎯⎯→ = + − (1)

At node O, 1

11 (1 / 2) 1/

1 2 / 2o o

o oV V V s V V s V s

s s−

+ = = ⎯⎯→ = + − (2)

Substituting (2) into (1) gives 1 12 / (2 1/ )(1 / 2) (2 )o os s s V Vs s

= + + − + −

2 2

(4 1)( 1.5 1) 1.5 1o

s A Bs CVs s s s s s

+ += = +

+ + + +

2 24 1 ( 1.5 1)s A s s Bs Cs+ = + + + + We equate coefficients. s2 : 0 = A+ B or B = - A s: 4=1.5A + C constant: 1 = A, B=-1, C = 4-1.5A = 2.5

2 22

2 2

3.25 747

1 2.5 1 3/ 4 41.5 1 7 7( 3/ 4) ( 3 / 4)

4 4

o

x

s sVs s s s

s s

− + += + = − +

+ + ⎛ ⎞ ⎛ ⎞+ + + +⎜ ⎟ ⎜ ⎟

⎝ ⎠ ⎝ ⎠

3 / 4 3 / 47 7( ) ( ) cos 4.9135 sin4 4

t tv t u t e t e t− −= − +

+ _

Page 11: Solucionario Capitulo 16 Sadiku

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Chapter 16, Problem 8. If v 0 (0) = -1V,obtain v 0 (t) in the circuit of Fig. 16.42.

Figure 16.42 For Prob. 16.8.

Page 12: Solucionario Capitulo 16 Sadiku

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Chapter 16, Solution 8.

1 1 22

FsC s

⎯⎯→ =

We analyze the circuit in the s-domain as shown below. We apply nodal analysis.

0

3 1 414021 1 ( 4)

o o oV V V ss s s Vs s

s

− − − − −+ + = ⎯⎯→ =

+

4oA BVs s

= ++

14 187 / 2, 9 / 24 4

A B= = = = −−

7 / 2 9 / 24oV

s s= −

+

47 9( ) ( )2 2

tov t e u t−⎛ ⎞= −⎜ ⎟

⎝ ⎠

1 Vo 1

+ _

+ _

+ _

2s

1s−

4s

3s

Page 13: Solucionario Capitulo 16 Sadiku

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Chapter 16, Problem 9. Find the input impedance Z in (s) of each of the circuits in Fig. 16.43.

Figure 16.43 For Prob. 16.9. Chapter 16, Solution 9.

(a) The s-domain form of the circuit is shown in Fig. (a).

=+++

=+=s1s2)s1s(2

)s1s(||2Zin 1s2s)1s(2

2

2

+++

(b) The s-domain equivalent circuit is shown in Fig. (b).

2s3)2s(2

s23)s21(2

)s21(||2++

=++

=+

2s36s5

)s21(||21++

=++

=⎟⎠⎞

⎜⎝⎛

++

+

⎟⎠⎞

⎜⎝⎛

++

⋅=⎟

⎠⎞

⎜⎝⎛

++

=

2s36s5

s

2s36s5

s

2s36s5

||sZin 6s7s3)6s5(s

2 +++

2

s

1/s

(a) (b)

2 s 2/s

1

1

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Chapter 16, Problem 10. Use Thevenin’s theorem to determine v 0 (t), t > 0 in the circuit of Fig. 16.44.

Figure 16.44 For Prob. 16.10.

Chapter 16, Solution 10. 1 1H s⎯⎯→ and iL(0) = 0 (the sources is zero for all t<0).

1 1 44

FsC s

⎯⎯→ = and vC(0) = 0 (again, there are no source

contributions for all t<0). To find ZTh , consider the circuit below. 1 s ZTh 2

21//( 2)

3ThsZ ss+

= + =+

Page 15: Solucionario Capitulo 16 Sadiku

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To find VTh, consider the circuit below. 1 s

+

102s +

VTh 2

-

2 10 103 2 3Th

sVs s s+

= =+ + +

The Thevenin equivalent circuit is shown below ZTh + 4/s Vo VTh –

2 3 2

404 4 310 40 3

4 4 2 3 6 12 ( 3) ( 3)3

o Th

Th

s sV V s s s s sZs s s

= = = =+ + + + + ++ ++

.

3( ) 23.094 sin 3t

ov t e t−=

+ _

+ _

Page 16: Solucionario Capitulo 16 Sadiku

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Chapter 16, Problem 11. Solve for the mesh currents in the circuit of Fig. 16.45. You may leave your results in the s-domain.

Figure 16.45 For Prob. 16.11.

Page 17: Solucionario Capitulo 16 Sadiku

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Chapter 16, Solution 11. In the s-domain, the circuit is as shown below.

1 210 1(1 )

4 4s I sI

s= + − (1)

1 21 5(4 ) 04 4

sI I s− + + = (2)

In matrix form,

1

2

110 14 4

1 50 44 4

s s Is

Is s

⎡ ⎤+ −⎡ ⎤ ⎢ ⎥ ⎡ ⎤⎢ ⎥ = ⎢ ⎥ ⎢ ⎥⎢ ⎥ ⎣ ⎦⎢ ⎥− +⎢ ⎥⎣ ⎦ ⎢ ⎥⎣ ⎦

4s49s

41 2 ++=∆

1

10 140 504

5 40 44

ss

ss

−∆ = = +

+

2

10154

1 204

ss

s

+∆ = =

)16s9s(s160s50

4s25.2s25.0225

s40

I 221

1++

+=

++

+=

∆∆

=

16s9s10

4s25.2s25.05.2I 22

22

++=

++=

∆∆

=

1 Ω 4

+ _ I1 I2

1 H4 1 s

10s

Page 18: Solucionario Capitulo 16 Sadiku

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Chapter 16, Problem 12. Find v o (t) in the circuit of Fig. 16.46.

Figure 16.46 For Prob. 16.12.

Page 19: Solucionario Capitulo 16 Sadiku

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Chapter 16, Solution 12. We apply nodal analysis to the s-domain form of the circuit below.

oo

osV2

4V

s3

s

V1s

10

+=+−

+

1s15s1510

151s

10V)ss25.01( o

2

+++

=++

=++

1s25.0sCBs

1sA

)1s25.0s)(1s(25s15

V 22o +++

++

=+++

+=

740

V)1s(A 1-so =+= =

)1s(C)ss(B)1s25.0s(A25s15 22 ++++++=+

Equating coefficients :

2s : -ABBA0 =⎯→⎯+= 1s : C-0.75ACBA25.015 +=++= 0s : CA25 +=

740A = , 740-B = , 7135C =

43

21

s

23

32

7155

43

21

s

21

s

740

1s1

740

43

21

s

7135

s740-

1s740

V 222o

+⎟⎠⎞

⎜⎝⎛+

⎟⎠⎞

⎜⎝⎛

⋅++⎟

⎠⎞

⎜⎝⎛+

+−

+=

+⎟⎠⎞

⎜⎝⎛+

++

+=

⎟⎟⎠

⎞⎜⎜⎝

⎛+⎟⎟⎠

⎞⎜⎜⎝

⎛−= t

23

sine)3)(7()2)(155(

t23

cose740

e740

)t(v 2t-2t-t-o

=)t(vo V)t866.0sin(e57.25)t866.0cos(e714.5e714.5 2-t2-t-t +−

s

3/s 4 1/(2s) + −

10/(s + 1)

Vo

Page 20: Solucionario Capitulo 16 Sadiku

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Chapter 16, Problem 13. Determine i 0 (t) in the circuit of Fig. 16.47.

Figure 16.47 For Prob. 16.13. Chapter 16, Solution 13. Consider the following circuit.

Applying KCL at node o,

ooo V

1s21s

s12V

1s2V

2s1

++

=+

++

=+

)2s)(1s(1s2

Vo +++

=

2sB

1sA

)2s)(1s(1

1s2V

I oo +

++

=++

=+

=

1A = , -1B =

2s1

1s1

Io +−

+=

=)t(io ( ) A)t(uee -2t-t −

2s

2 1

1/s

1/(s + 2)

Vo

Io

Page 21: Solucionario Capitulo 16 Sadiku

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Chapter 16, Problem 14. * Determine i 0 (t) in the network shown in Fig. 16.48.

Figure 16.48 For Prob. 16.14. * An asterisk indicates a challenging problem. Chapter 16, Solution 14. We first find the initial conditions from the circuit in Fig. (a).

A5)0(io =− , V0)0(vc =−

We now incorporate these conditions in the s-domain circuit as shown in Fig.(b).

4 Ω1 Ω

+ −

5 V

(a)

+

vc(0)

io

4/s

4 1

+ −

15/s

Vo

Io

(b)

5/s 2s

Page 22: Solucionario Capitulo 16 Sadiku

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At node o,

0s440V

s5

s2V

1s15V ooo =

+−

+++−

oV)1s(4

ss2

11

s5

s15 ⎟

⎞⎜⎝

+++=−

o

2

o

22

V)1s(s42s6s5

V)1s(s4

s2s2s4s4s

10+++

=+

++++=

2s6s5)1s(40

V 2o +++

=

s5

)4.0s2.1s(s)1s(4

s5

s2V

I 2o

o +++

+=+=

4.0s2.1sCBs

sA

s5

I 2o +++

++=

sCsB)4.0s2.1s(A)1s(4 s2 ++++=+

Equating coefficients :

0s : 10AA4.04 =⎯→⎯= 1s : -84-1.2ACCA2.14 =+=⎯→⎯+= 2s : -10-ABBA0 ==⎯→⎯+=

4.0s2.1s8s10

s10

s5

I 2o +++

−+=

2222o 2.0)6.0s()2.0(10

2.0)6.0s()6.0s(10

s15

I++

−++

+−=

=)t(io ( )[ ] A)t(u)t2.0sin()t2.0cos(e1015 0.6t- −−

Page 23: Solucionario Capitulo 16 Sadiku

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.

Chapter 16, Problem 15. Find V x (s) in the circuit shown in Fig. 16.49.

Figure 16.49 For Prob. 16.15. Chapter 16, Solution 15. First we need to transform the circuit into the s-domain.

2s5VV

2s5VV,But

2ss5V120V)40ss2(0

2ss5sVVs2V120V40

010

2s5V

s/50V

4/sV3V

xoox

xo2

oo2

xo

ooxo

++=→

+−=

+−−++==

+−++−

=+−

+−

+−

We can now solve for Vx.

)40s5.0s)(2s()20s(5V

2s)20s(10V)40s5.0s(2

02s

s5V1202s

5V)40ss2(

2

2x

2x

2

xx2

−++

+−=

++

−=−+

=+

−−⎟⎠⎞

⎜⎝⎛

++++

10

3Vx

+ Vx −

s/4

5/s 2s5+

+ − +

Vo

Page 24: Solucionario Capitulo 16 Sadiku

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.

Chapter 16, Problem 16. * Find i 0 (t) for t > 0 in the circuit of Fig. 16.50.

Figure 16.50 For Prob. 16.16. * An asterisk indicates a challenging problem.

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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.

Chapter 16, Solution 16. We first need to find the initial conditions. For 0t < , the circuit is shown in Fig. (a).

To dc, the capacitor acts like an open circuit and the inductor acts like a short circuit. Hence,

A1-33-

i)0(i oL === , V1-vo =

V5.221-

)1-)(2(-)0(vc =⎟⎠⎞

⎜⎝⎛

−=

We now incorporate the initial conditions for 0t > as shown in Fig. (b).

For mesh 1,

02

Vs5.2

Is1

Is1

22s

5- o21 =++−⎟

⎠⎞

⎜⎝⎛

+++

(a)

3 V

2 Ω

+ −

io1 H + Vo/2

1 F

+ −Vo

1 Ω

(b)

-1 V

2

− +

Io

+ Vo/2

1/s

+ −Vo

1

+ −

2.5/s

s

+ −

5/(s + 2) I1 I2

Page 26: Solucionario Capitulo 16 Sadiku

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.

But, 2oo IIV ==

s5.2

2s5

Is1

21

Is1

2 21 −+

=⎟⎠⎞

⎜⎝⎛

−+⎟⎠⎞

⎜⎝⎛

+ (1)

For mesh 2,

0s5.2

2V

1Is1

Is1

s1 o12 =−−+−⎟

⎠⎞

⎜⎝⎛

++

1s5.2

Is1

s21

Is1

- 21 −=⎟⎠⎞

⎜⎝⎛

+++ (2)

Put (1) and (2) in matrix form.

⎥⎥⎥⎥

⎢⎢⎢⎢

−+

=⎥⎥

⎢⎢

⎥⎥⎥⎥

⎢⎢⎢⎢

++

−+

1s5.2

s5.2

2s5

I

I

s1

s21

s1-

s1

21

s1

2

2

1

s3

2s2 ++=∆ , )2s(s

5s4

2-2 +++=∆

3s2s2CBs

2sA

)3s2s2)(2s(132s-

II 22

22

2o +++

++

=+++

+=

∆∆

==

)2s(C)s2s(B)3s2s2(A132s- 222 ++++++=+

Equating coefficients :

2s : BA22- += 1s : CB2A20 ++= 0s : C2A313 +=

Solving these equations leads to

7143.0A = , -3.429B = , 429.5C =

5.1ss714.2s7145.1

2s7143.0

3s2s2429.5s429.3

2s7143.0

I 22o ++−

−+

=++

−−

+=

25.1)5.0s()25.1)(194.3(

25.1)5.0s()5.0s(7145.1

2s7143.0

I 22o +++

+++

−+

=

=)t(io [ ] A)t(u)t25.1sin(e194.3)t25.1cos(e7145.1e7143.0 -0.5t-0.5t-2t +−

Page 27: Solucionario Capitulo 16 Sadiku

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.

Chapter 16, Problem 17. Calculate i 0 (t) for t > 0 in the network of Fig. 16.51.

Figure 16.51 For Prob. 16.17. Chapter 16, Solution 17. We apply mesh analysis to the s-domain form of the circuit as shown below. For mesh 3,

0IsIs1

Is1

s1s

2213 =−−⎟

⎠⎞

⎜⎝⎛++

+ (1)

For the supermesh,

0Iss1

I)s1(Is1

1 321 =⎟⎠⎞

⎜⎝⎛

+−++⎟⎠⎞

⎜⎝⎛+ (2)

s

1 1

1/s

2/(s+1)

+ −

I3

I2I1

4/s

Page 28: Solucionario Capitulo 16 Sadiku

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.

Adding (1) and (2) we get, I1 + I2 = –2/(s+1) (3) But –I1 + I2 = 4/s (4) Adding (3) and (4) we get, I2 = (2/s) – 1/(s+1) (5) Substituting (5) into (4) yields, I1 = –(2/s) – (1/(s+1)) (6) Substituting (5) and (6) into (1) we get,

1s

2Is

1s1s

s2)1s(s

1s2

32

2 +−=⎟

⎟⎠

⎞⎜⎜⎝

⎛ ++

++−

++

js

j5.05.1js

j5.05.1s2I3 −

++

+−

+−=

Substituting (3) into (1) and (2) leads to

)1s(s)2s2s(2I

s1sI

s1s- 2

232

+

++−=⎟

⎠⎞

⎜⎝⎛ ++⎟

⎠⎞

⎜⎝⎛ + (4)

232s

)1s(4Is1sI

s1s2 +

−=⎟⎠⎞

⎜⎝⎛ +−⎟

⎠⎞

⎜⎝⎛ ++ (5)

We can now solve for Io. Io = I2 – I3 = (4/s) – (1/(s+1)) + ((–1.5+0.5j)/(s+j)) + ((–1.5–0.5)/(s–j)) or io(t) = [4 – e–t + 1.5811e–jt+161.57˚ + 1.5811ejt–161.57˚]u(t)A This is a challenging problem. I did check it with using a Thevenin equivalent circuit and got the same exact answer.

Page 29: Solucionario Capitulo 16 Sadiku

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.

Chapter 16, Problem 18. (a) Find the Laplace transform of the voltage shown in Fig. 16.52(a). (b) Using that value of v s (t) in the circuit shown in Fig. 16.52(b), find the value of v 0 (t).

Figure 16.52 For Prob. 16.18. Chapter 16, Solution 18.

vs(t) = 3u(t) – 3u(t–1) or Vs = )e1(s3

se

s3 s

s−

−−=−

V)]1t(u)e22()t(u)e22[()t(v

)e1(5.1s

2s2)e1(

)5.1s(s3V

VV)5.1s(02

VsV

1VV

)1t(5.1t5.1o

sso

soo

oso

−−−−=

−⎟⎠⎞

⎜⎝⎛

+−=−

+=

=+→=++−

−−−

−−

1 Ω

1/s Vs

+ − 2 Ω

+

Vo

Page 30: Solucionario Capitulo 16 Sadiku

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.

Chapter 16, Problem 19.

In the circuit of Fig. 16.53, let i(0) = 1 A, v 0 (0) and v s = 4e t2− u(t) V. Find v 0 (t) for t > 0.

Figure 16.53 For Prob. 16.19.

Page 31: Solucionario Capitulo 16 Sadiku

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.

Chapter 16, Solution 19. We incorporate the initial conditions in the s-domain circuit as shown below. At the supernode,

o11 sV

s1

sV

22

V))2s(4(++=+

−+

o1 Vss1

Vs1

21

22s

2++⎟

⎠⎞

⎜⎝⎛

+=++

(1)

But I2VV 1o += and s

1VI 1 +=

2s2Vs

s)2s(s2V

Vs

)1V(2VV oo

11

1o +−

=+−

=⎯→⎯+

+= (2)

Substituting (2) into (1)

oo Vs2s

2V2s

ss22s

s12

2s2

+⎥⎦

⎤⎢⎣

⎡+

−⎟⎠⎞

⎜⎝⎛

+⎟⎠⎞

⎜⎝⎛ +

=−++

oVs21

s1

s12

2s2

⎥⎦

⎤⎢⎣

⎡+⎟

⎠⎞

⎜⎝⎛=+−+

+

oV)2/1s(2s6s2

)2s(24s2

+=++

=+++

2sB

2/1sA

)2/1s)(2s(6s2Vo +

++

=+++

=

333.3)25.0/()61(A =+−+−= , 3333.1)2/12/()64(B −=+−+−=

2s3333.1

2/1s333.3Vo +

−+

=

Therefore, =)t(vo (3.333e-t/2 – 1.3333e-2t)u(t) V

2

+ −

s

1/s

VoV1

2 I

− +

2 4/(s + 2)

1/s

I

Page 32: Solucionario Capitulo 16 Sadiku

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.

Chapter 16, Problem 20. Find v 0 (t) in the circuit of Fig. 16.54 if v x (0) = 2 V and i(0) = 1A.

Figure 16.54 For Prob. 16.20.

Page 33: Solucionario Capitulo 16 Sadiku

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.

Chapter 16, Solution 20. We incorporate the initial conditions and transform the current source to a voltage source as shown.

At the main non-reference node, KCL gives

s1

sV

1V

s11Vs2)1s(1 ooo ++=

+−−+

s1sV)s11)(1s(Vs2

1ss

oo+

+++=−−+

oV)s12s2(2s

1s1s

s++=−

+−

+

)1s2s2)(1s(1s4s2-

V 2

2

o +++−−

=

5.0ssCBs

1sA

)5.0ss)(1s(5.0s2s-

V 22o +++

++

=+++

−−=

1V)1s(A 1-so =+= =

)1s(C)ss(B)5.0ss(A5.0s2s- 222 ++++++=−−

Equating coefficients :

2s : -2BBA1- =⎯→⎯+= 1s : -1CCBA2- =⎯→⎯++= 0s : -0.515.0CA5.00.5- =−=+=

222o )5.0()5.0s()5.0s(2

1s1

5.0ss1s2

1s1

V++

+−

+=

+++

−+

=

=)t(vo [ ] V)t(u)2tcos(e2e 2-t-t −

1

+ −

Vo

2/s

1/s

1/s + −

1 s 1/(s + 1)

Page 34: Solucionario Capitulo 16 Sadiku

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.

Chapter 16, Problem 21. Find the voltage v 0 (t) in the circuit of Fig. 16.55 by means of the Laplace transform.

Figure 16.55 For Prob. 16.21.

Page 35: Solucionario Capitulo 16 Sadiku

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Chapter 16, Solution 21. The s-domain version of the circuit is shown below. 1 s

V1 Vo + 2/s 2 1/s

- At node 1,

ooo VsVsVs

sVVV

s )12

()1(1021

102

11

1−++=⎯→⎯+

−=

− (1)

At node 2,

)12

(2

21

1 ++=⎯→⎯+=− ssVVsVVsVV

oooo (2)

Substituting (2) into (1) gives

ooo VsssVsVsss )5.12()12

()12/)(1(10 22

2 ++=−++++=

5.12)5.12(10

22 +++

+=++

=ss

CBssA

sssVo

CsBsssA ++++= 22 )5.12(10

BAs +=0:2 CAs += 20:

-40/3C -20/3,B ,3/205.110:constant ===⎯→⎯= AA

⎥⎦

⎤⎢⎣

⎡++

−+++

−=⎥⎦⎤

⎢⎣⎡

+++

−= 22222 7071.0)1(7071.0414.1

7071.0)1(11

320

5.1221

320

sss

ssss

sVo

Taking the inverse Laplace tranform finally yields

[ ] V)t(ut7071.0sine414.1t7071.0cose1320)t(v tt

o−− −−=

10/s

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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.

Chapter 16, Problem 22. Find the node voltages v 1 and v 2 in the circuit of Fig. 16.56 using the Laplace transform technique. Assume that i s = 12e t− u(t) A and that all initial conditions are zero.

Figure 16.56 For Prob. 16.22. Chapter 16, Solution 22. The s-domain version of the circuit is shown below. 4s V1 V2

1s

12+

1 2 3/s

At node 1,

s4V

s411V

1s12

s4VV

1V

1s12 2

1211 −⎟

⎠⎞

⎜⎝⎛ +=

+⎯→⎯

−+=

+ (1)

At node 2,

⎟⎠⎞

⎜⎝⎛ ++=⎯→⎯+=

−1s2s

34VVV

3s

2V

s4VV 2

212221 (2)

Substituting (2) into (1),

222

2 V23s

37s

34

s41

s4111s2s

34V

1s12

⎟⎠⎞

⎜⎝⎛ ++=⎥

⎤⎢⎣

⎡−⎟

⎠⎞

⎜⎝⎛ +⎟⎠⎞

⎜⎝⎛ ++=

+

)89s

47s(

CBs)1s(

A

)89s

47s)(1s(

9V22

2++

++

+=

+++=

)1s(C)ss(B)89s

47s(A9 22 ++++++=

Page 37: Solucionario Capitulo 16 Sadiku

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.

Equating coefficients:

BA0:s2 +=

A43CCA

43CBA

470:s −=⎯→⎯+=++=

-18C -24,B ,24AA83CA

899:constant ===⎯→⎯=+=

6423)

87s(

3

6423)

87s(

)8/7s(24)1s(

24

)89s

47s(

18s24)1s(

24V222

2++

+++

+−

+=

++

+−

+=

Taking the inverse of this produces:

[ ] )t(u)t5995.0sin(e004.5)t5995.0cos(e24e24)t(v t875.0t875.0t2

−−− +−= Similarly,

)89s

47s(

FEs)1s(

D

)89s

47s)(1s(

1s2s349

V22

2

1++

++

+=

+++

⎟⎠⎞

⎜⎝⎛ ++

=

)1s(F)ss(E)89s

47s(D1s2s

349 222 ++++++=⎟

⎠⎞

⎜⎝⎛ ++

Equating coefficients:

ED12:s2 +=

D436FFD

436or FED

4718:s −=⎯→⎯+=++=

0F 4,E ,8DD833or FD

899:constant ===⎯→⎯=+=

6423)

87s(

2/7

6423)

87s(

)8/7s(4)1s(

8

)89s

47s(

s4)1s(

8V222

1++

−++

++

+=

+++

+=

Thus,

[ ] )t(u)t5995.0sin(e838.5)t5995.0cos(e4e8)t(v t875.0t875.0t1

−−− −+=

Page 38: Solucionario Capitulo 16 Sadiku

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.

Chapter 16, Problem 23. Consider the parallel RLC circuit of Fig. 16.57. Find v(t) and i(t) given that v(0) = 5 and i(0) = -2 A.

Figure 16.57 For Prob. 16.23.

Page 39: Solucionario Capitulo 16 Sadiku

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.

Chapter 16, Solution 23. The s-domain form of the circuit with the initial conditions is shown below. At the non-reference node,

sCVsLV

RV

C5s2

s4

++=++

⎟⎠⎞

⎜⎝⎛

++=+

LC1

RCs

ss

CVs

sC56 2

LC1RCssC6s5

V 2 +++

=

But 88010

1RC1

== , 208041

LC1

==

22222 2)4s()2)(230(

2)4s()4s(5

20s8s480s5

V++

+++

+=

+++

=

=)t(v V)t(u))t2sin(e230)t2cos(e5( -4t-4t +

)20s8s(s4480s5

sLV

I 2 +++

==

20s8sCBs

sA

)20s8s(s120s25.1

I 22 +++

+=++

+=

6A = , -6B = , -46.75C =

22222 2)4s()2)(375.11(

2)4s()4s(6

s6

20s8s75.46s6

s6

I++

−++

+−=

+++

−=

=)t(i 0t),t(u))t2sin(e375.11)t2cos(e66( -4t-4t >−−

-2/s R sL 1/sC 4/s

VI

5C

Page 40: Solucionario Capitulo 16 Sadiku

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.

Chapter 16, Problem 24. The switch in Fig. 16.58 moves from position 1 to position 2 at t =0. Find v(t), for all t > 0.

Figure 16.58 For Prob. 16.24. Chapter 16, Solution 24. When the switch is position 1, v(0)=12, and iL(0) = 0. When the switch is in position 2, we have the circuit as shown below. s/4 + 100/s v 12/s

1 10010 0.01mF FsC s

= ⎯⎯→ =

2

12 / 48/ 4 100 / 400

sIs s s

= =+ +

, 2

124 400s sV sLI I

s= = =

+

( ) 12cos 20 , 0v t t t= >

+ _

Page 41: Solucionario Capitulo 16 Sadiku

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.

Chapter 16, Problem 25. For the RLC circuit shown in Fig. 16.59, find the complete response if v(0) = 2 V when the switch is closed.

Figure 16.59 For Prob. 16.25. Chapter 16, Solution 25. For 0t > , the circuit in the s-domain is shown below.

s

2/s

9/s

6

+ −

(2s)/(s2 + 16) + −

I

+

V

Page 42: Solucionario Capitulo 16 Sadiku

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.

Applying KVL,

0s2

Is9

s616ss2

2 =+⎟⎠⎞

⎜⎝⎛

++++−

)16s)(9s6s(32I

22 +++

−=

)16s()3s(s288

s2

s2I

s9V 22 ++

−+=+=

16sEDs

)3s(C

3sB

sA

s2

22 ++

++

++

++=

)s48s16s3s(B)144s96s25s6s(A288- 234234 ++++++++=

)s9s6s(E)s9s6s(D)s16s(C 232343 ++++++++

Equating coefficients : 0s : A144288 =− (1) 1s : E9C16B48A960 +++= (2) 2s : E6D9B16A250 +++= (3) 3s : ED6CB3A60 ++++= (4) 4s : DBA0 ++= (5)

Solving equations (1), (2), (3), (4) and (5) gives

2A −= , 202.2B = , 84.3C = , 202.0-D = , 766.2E =

16s)4)(6915.0(

16ss202.0

)3s(84.3

3s202.2)s(V 222 +

++

−+

++

=

=)t(v 2.202e-3t + 3.84te-3t – 0.202cos(4t) + 0.6915sin(4t)u(t) V

Page 43: Solucionario Capitulo 16 Sadiku

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.

Chapter 16, Problem 26.

For the op amp circuit in Fig. 16.60, find v 0 (t) for t > 0. Take v s = 3e t5− u(t) V.

Figure 16.60 For Prob. 16.26.

Page 44: Solucionario Capitulo 16 Sadiku

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.

Chapter 16, Solution 26. Consider the op-amp circuit below.

At node 0,

sC)V0(R

V0R

0Vo

2

o

1

s −+−

=−

( )o2

1s V-sCR1

RV ⎟⎠

⎞⎜⎝

⎛+=

211s

o

RRCsR1-

VV

+=

But 21020

RR

2

1 == , 1)1050)(1020(CR 6-31 =××=

So, 2s

1-VV

s

o

+=

)5s(3Ve3V s-5t

s +=⎯→⎯=

5)2)(s(s3-

Vo ++=

5sB

2sA

5)2)(s(s3

V- o ++

+=

++=

1A = , -1B =

2s1

5s1

Vo +−

+=

=)t(vo ( ) )t(uee -2t-5t −

−+

1/sC

R1

R2

+ −

Vs

0

+Vo−

Page 45: Solucionario Capitulo 16 Sadiku

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.

Chapter 16, Problem 27. Find I 1 (s) and I 2 (s) in the circuit of Fig. 16.61.

Figure 16.61 For Prob. 16.27.

Page 46: Solucionario Capitulo 16 Sadiku

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.

Chapter 16, Solution 27. Consider the following circuit.

For mesh 1,

221 IsII)s21(3s

10−−+=

+

21 I)s1(I)s21(3s

10+−+=

+ (1)

For mesh 2,

112 IsII)s22(0 −−+=

21 I)1s(2I)s1(-0 +++= (2) (1) and (2) in matrix form,

⎥⎦

⎤⎢⎣

⎡⎥⎦

⎤⎢⎣

⎡++++

=⎥⎦

⎤⎢⎣

⎡ +

2

1

II

)1s(2)1s(-)1s(-1s2

0)3s(10

1s4s3 2 ++=∆

3s)1s(20

1 ++

=∆

3s)1s(10

2 ++

=∆

Thus

=∆∆

= 11I )1s4s3)(3s(

)1s(202 ++++

=∆∆

= 22I

)1s4s3)(3s()1s(10

2 ++++

2I1=

2s

1 10/(s + 3) + −

I1

2s

1 I2

s

Page 47: Solucionario Capitulo 16 Sadiku

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.

Chapter 16, Problem 28. For the circuit in Fig. 16.62, find v 0 (t) for t > 0.

Figure 16.62 For Prob. 16.28.

Page 48: Solucionario Capitulo 16 Sadiku

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.

Chapter 16, Solution 28. Consider the circuit shown below. For mesh 1,

21 IsI)s21(s6

++= (1)

For mesh 2,

21 I)s2(Is0 ++=

21 Is2

1-I ⎟⎠⎞

⎜⎝⎛+= (2)

Substituting (2) into (1) gives

2

2

22 Is

2)5s(s-IsI

s2

12s)-(1s6 ++

=+⎟⎠⎞

⎜⎝⎛++=

or 2s5s

6-I 22 ++=

4.561)0.438)(s(s12-

2s5s12-

I2V 22o ++=

++==

Since the roots of 02s5s2 =++ are -0.438 and -4.561,

561.4sB

438.0sA

Vo ++

+=

-2.914.123

12-A == , 91.2

4.123-12-

B ==

561.4s91.2

0.438s2.91-

)s(Vo ++

+=

=)t(vo [ ] V)t(uee91.2 t438.0-4.561t −

s

2 I2s 2s

1

+ −

6/s I1 +

Vo

Page 49: Solucionario Capitulo 16 Sadiku

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.

Chapter 16, Problem 29. For the ideal transformer circuit in Fig. 16.63, determine i 0 (t).

Figure 16.63 For Prob. 16.29. Chapter 16, Solution 29. Consider the following circuit.

Let 1s2

8s48)s4)(8(

s4

||8ZL +=

+==

When this is reflected to the primary side,

2n,nZ

1Z 2L

in =+=

1s23s2

1s22

1Zin ++

=+

+=

3s21s2

1s10

Z1

1s10

Iin

o ++

⋅+

=⋅+

=

5.1sB

1sA

)5.1s)(1s(5s10

Io ++

+=

+++

=

-10A = , 20B =

5.1s20

1s10-

)s(Io ++

+=

=)t(io [ ] A)t(uee210 t-1.5t −−

8 4/s

1

10/(s + 1) + −

Io 1 : 2

Page 50: Solucionario Capitulo 16 Sadiku

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.

Chapter 16, Problem 30. The transfer function of a system is

H(s) = 13

2

+ss

Find the output when the system has an input of 4e 3/t− u(t). Chapter 16, Solution 30.

)s(X)s(H)s(Y = , 1s3

1231s

4)s(X

+=

+=

22

2

)1s3(34s8

34

)1s3(s12

)s(Y++

−=+

=

22 )31s(1

274

)31s(s

98

34

)s(Y+

⋅−+

⋅−=

Let 2)31s(s

98-

)s(G+

⋅=

Using the time differentiation property,

⎟⎠⎞

⎜⎝⎛

+=⋅= 3t-3t-3t- eet31-

98-

)et(dtd

98-

)t(g

3t-3t- e98

et278

)t(g −=

Hence,

3t-3t-3t- et274

e98

et278

)t(u34

)t(y −−+=

=)t(y 3t-3t- et274

e98

)t(u34

+−

Page 51: Solucionario Capitulo 16 Sadiku

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.

Chapter 16, Problem 31. When the input to a system is a unit step function, the response is 10 cos 2tu(t). Obtain the transfer function of the system. Chapter 16, Solution 31.

s1

)s(X)t(u)t(x =⎯→⎯=

4ss10

)s(Y)t2cos(10)t(y 2 +=⎯→⎯=

==)s(X)s(Y

)s(H4s

s102

2

+

Page 52: Solucionario Capitulo 16 Sadiku

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.

Chapter 16, Problem 32. A circuit is known to have its transfer function as

H(s) = 54

32 ++

+ss

s

Find its output when: (a) the input is a unit step function (b) the input is 6te t2− u(t). Chapter 16, Solution 32.

(a) )s(X)s(H)s(Y =

s1

5s4s3s

2 ⋅++

+=

5s4s

CBssA

)5s4s(s3s

22 +++

+=++

+=

CsBs)5s4s(A3s 22 ++++=+

Equating coefficients :

0s : 53AA53 =⎯→⎯= 1s : 57- A41CCA41 =−=⎯→⎯+= 2s : 53--ABBA0 ==⎯→⎯+=

5s4s7s3

51

s53

)s(Y 2 +++

⋅−=

1)2s(1)2s(3

51

s6.0

)s(Y 2 ++++

⋅−=

=)t(y [ ] )t(u)tsin(e2.0)tcos(e6.06.0 -2t-2t −−

Page 53: Solucionario Capitulo 16 Sadiku

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.

(b) 22t-

)2s(6

)s(Xet6)t(x+

=⎯→⎯=

22 )2s(6

5s4s3s

)s(X)s(H)s(Y+

⋅++

+==

5s4sDCs

)2s(B

2sA

)5s4s()2s()3s(6

)s(Y 2222 +++

++

++

=+++

+=

Equating coefficients :

3s : -ACCA0 =⎯→⎯+= (1) 2s : DBA2DC4BA60 ++=+++= (2) 1s : D4B4A9D4C4B4A136 ++=+++= (3) 0s : BA2D4B5A1018 +=++= (4)

Solving (1), (2), (3), and (4) gives

6A = , 6B = , 6-C = , -18D =

1)2s(18s6

)2s(6

2s6

)s(Y 22 +++

−+

++

=

1)2s(6

1)2s()2s(6

)2s(6

2s6

)s(Y 222 ++−

+++

−+

++

=

=)t(y [ ] )t(u)tsin(e6)tcos(e6et6e6 -2t-2t-2t-2t −−+

Page 54: Solucionario Capitulo 16 Sadiku

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.

Chapter 16, Problem 33. When a unit step is applied to a system at t = 0 its response is

y(t) = ⎥⎦⎤

⎢⎣⎡ +−+ −− )4sin34cos2(

214 23 ttee tt u(t)

What is the transfer function of the system? Chapter 16, Solution 33.

)s(X)s(Y

)s(H = , s1

)s(X =

16)2s()4)(3(

16)2s(s2

)3s(21

s4

)s(Y 22 ++−

++−

++=

== )s(Ys)s(H20s4s

s1220s4s)2s(s2

)3s(2s4 22 ++

−++

+−

++

Page 55: Solucionario Capitulo 16 Sadiku

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.

Chapter 16, Problem 34. For the circuit in Fig. 16.64, find H(s) = V 0 (s)/V s (s). Assume zero initial conditions.

Figure 16.64 For Prob. 16.34. Chapter 16, Solution 34. Consider the following circuit.

Using nodal analysis,

s10V

4V

2sVV ooos +=

+−

o2

os V)s2s(101

)2s(41

1V10s

41

2s1

)2s(V ⎟⎠⎞

⎜⎝⎛

++++=⎟⎠⎞

⎜⎝⎛

+++

+=

( ) o2

s V30s9s2201

V ++=

=s

o

VV

30s9s220

2 ++

s

4

2

+ −

Vs 10/s

Vo

+

Vo(s)

Page 56: Solucionario Capitulo 16 Sadiku

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.

Chapter 16, Problem 35. Obtain the transfer function H(s) = V 0 /V s for the circuit of Fig. 16.65.

Figure 16.65 For Prob. 16.35. Chapter 16, Solution 35. Consider the following circuit.

At node 1,

3sV

II2 1

+=+ , where

s2VV

I 1s −=

3sV

s2VV

3 11s

+=

−⋅

1s1 V

2s3

V2s3

3sV

−=+

s1 V2s3

V2s3

3s1

=⎟⎠⎞

⎜⎝⎛

++

s21 V2s9s3

)3s(s3V

+++

=

s21o V2s9s3

s9V

3s3

V++

=+

=

==s

o

VV

)s(H2s9s3

s92 ++

s

3 2I

2/s

+ −

Vs

V1I

+

Vo

Page 57: Solucionario Capitulo 16 Sadiku

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.

Chapter 16, Problem 36. The transfer function of a certain circuit is

H(s) = 1

5+s

- 2

3+s

+4

6+s

Find the impulse response of the circuit. Chapter 16, Solution 36.

Taking the inverse Laplace transform of each term gives

( )2 4( ) 5 3 6 ( )t t th t e e e u t− − −= − +

Page 58: Solucionario Capitulo 16 Sadiku

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.

Chapter 16, Problem 37. For the circuit in Fig. 16.66, find:

(a) I 1 /V s (b) I 2 /V x

Figure 16.66 For Prob. 16.37. Chapter 16, Solution 37.

(a) Consider the circuit shown below.

For loop 1,

21s Is2

Is2

3V −⎟⎠⎞

⎜⎝⎛+= (1)

For loop 2,

0Is2

Is2

s2V4 12x =−⎟⎠⎞

⎜⎝⎛

++

But, ⎟⎠⎞

⎜⎝⎛

−=s2

)II(V 21x

So, 0Is2

Is2

s2)II(s8

1221 =−⎟⎠⎞

⎜⎝⎛

++−

21 Is2s6

Is6-

0 ⎟⎠⎞

⎜⎝⎛

−+= (2)

+ −

Vs I2I1

2s 3

+ 4Vx 2/s

+

Vx

Page 59: Solucionario Capitulo 16 Sadiku

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.

In matrix form, (1) and (2) become

⎥⎦

⎤⎢⎣

⎡⎥⎦

⎤⎢⎣

⎡−

+=⎥⎦

⎤⎢⎣

2

1s

II

s2s6s6-s2-s23

0V

⎟⎠⎞

⎜⎝⎛⎟⎠⎞

⎜⎝⎛

−⎟⎠⎞

⎜⎝⎛

−⎟⎠⎞

⎜⎝⎛+=∆

s2

s6

s2s6

s2

3

4s6s

18−−=∆

s1 Vs2s6

⎟⎠⎞

⎜⎝⎛

−=∆ , s2 Vs6

=∆

s1

1 Vs64s18

)s2s6(I

−−−

=∆∆

=

=−−

−=

32s9ss3

VI

s

1

9s2s33s

2

2

−+−

(b) ∆∆

= 22I

⎟⎠⎞

⎜⎝⎛

∆∆−∆

=−= 2121x s

2)II(

s2

V

∆=

∆−−

= ssx

V4-)s6s2s6(Vs2V

==s

s

x

2

4V-Vs6

VI

2s3-

Page 60: Solucionario Capitulo 16 Sadiku

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.

Chapter 16, Problem 38. Refer to the network in Fig. 16.67. Find the following transfer functions:

(a) H 1 (s) = V 0 (s)/V s (s) (b) H 2 (s) = V 0 (s)/I s (s) (c) H 3 (s) = I 0 (s)/I s (s) (d) H 4 (s) = I 0 (s)/V s (s)

Figure 16.67 For Prob. 16.38.

Page 61: Solucionario Capitulo 16 Sadiku

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.

Chapter 16, Solution 38. (a) Consider the following circuit.

At node 1,

sVV

Vs1

VV o11

1s −+=

o1s Vs1

Vs1

s1V −⎟⎠⎞

⎜⎝⎛

++= (1)

At node o,

oooo1 V)1s(VVs

sVV

+=+=−

o2

1 V)1ss(V ++= (2) Substituting (2) into (1)

oo2

s Vs1V)1ss)(s11s(V −++++=

o23

s V)2s3s2s(V +++=

==s

o1 V

V)s(H

2s3s2s1

23 +++

(b) o

2o

231ss V)1ss(V)2s3s2s(VVI ++−+++=−=

o23

s V)1s2ss(I +++=

==s

o2 I

V)s(H

1s2ss1

23 +++

(c) 1

VI o

o =

==== )s(HIV

II

)s(H 2s

o

s

o3 1s2ss

123 +++

(d) ==== )s(HVV

VI

)s(H 1s

o

s

o4 2s3s2s

123 +++

s

1

1

+ −

Vs 1/s

V1 Vo Io

+

Vo

1/s

Is

Page 62: Solucionario Capitulo 16 Sadiku

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.

Chapter 16, Problem 39. Calculate the gain H(s) = V 0 /V s in the op amp circuit of Fig. 16.68.

Figure 16.68 For Prob. 16.39. Chapter 16, Solution 39. Consider the circuit below.

Since no current enters the op amp, oI flows through both R and C.

⎟⎠⎞

⎜⎝⎛

+=sC1

RI-V oo

sCI-

VVV osba ===

=+

==sC1

sC1RVV

)s(Hs

o 1sRC +

−+

Va

Vb R

1/sC

+ −

Vs Io

+

Vo

Page 63: Solucionario Capitulo 16 Sadiku

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.

Chapter 16, Problem 40. Refer to the RL circuit in Fig. 16.69. Find: (a) the impulse response h(t) of the circuit. (b) the unit step response of the circuit.

Figure 16.69 For Prob. 16.40. Chapter 16, Solution 40.

(a) LRs

LRsLR

RVV

)s(Hs

o

+=

+==

=)t(h )t(ueLR LRt-

(b) s1)s(V)t(u)t(v ss =⎯→⎯=

LRsB

sA

)LRs(sLR

VLRs

LRV so +

+=+

=+

=

1A = , -1B =

LRs1

s1

Vo +−=

=−= )t(ue)t(u)t(v L-Rt

o )t(u)e1( L-Rt−

Page 64: Solucionario Capitulo 16 Sadiku

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.

Chapter 16, Problem 41.

A parallel RL circuit has R = 4Ω and L = 1 H. The input to the circuit is i s (t) = 2e t− u(t)A. Find the inductor current i L (t) for all t > 0 and assume that i L (0) = -2 A.

Chapter 16, Solution 41. Consider the circuit as shown below.

24o o

sV VI

s s= + −

But 21SI

s=

+

2 1 1 2 4 2 2 4 2( )1 4 4 1 ( 1)o o

s sV Vs s s s s s s s

+ +⎛ ⎞= + − ⎯⎯→ = + =⎜ ⎟+ + +⎝ ⎠

8(2 1)( 1)( 4)o

sVs s

+=

+ +

8(2 1)( 1)( 4) 1 4

oL

V s A B CIs s s s s s s

+= = = + +

+ + + +

8(1) 8( 2 1) 8( 8 1)2, 8 / 3, 14 / 3

(1)(4) ( 1)(2) ( 4)( 3)A B C− + − += = = = = = −

− − −

2 8 / 3 14 / 31 4

oL

VIs s s s

−= = + +

+ +

48 14( ) 2 ( )3 3

t tLi t e e u t− −⎛ ⎞= + −⎜ ⎟

⎝ ⎠ = A)t(ue

314e

382 t4t ⎟

⎠⎞

⎜⎝⎛ −+ −−

4 Is s

I2

Vo

2s−

Page 65: Solucionario Capitulo 16 Sadiku

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.

Chapter 16, Problem 42. A circuit has a transfer function

H(s) = 2)2)(1(4++

+ss

s

Find the impulse response.

Chapter 16, Solution 42.

2 2

4( )( 1)( 2) 1 2 ( 2)

s A B CH ss s s s s

+= = + +

+ + + + +

2 2 24 ( 2) ( 1)( 2) ( 1) ( 2 4) ( 3 2) ( 1)s A s B s s C s A s s B s s C s+ = + + + + + + = + + + + + + + We equate coefficients. s2 : 0=A+B or B=-A s: 1=4A+3B+C=B+C constant: 4=4A+2B+C =2A+C Solving these gives A=3, B=-3, C=-2

2

3 3 2( )1 2 ( 2)

H ss s s

= − −+ + +

2 2( ) (3 3 2 ) ( )t t th t e e te u t− − −= − −

Page 66: Solucionario Capitulo 16 Sadiku

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.

Chapter 16, Problem 43. Develop the state equations for Prob. 16.1. Chapter 16, Solution 43.

First select the inductor current iL and the capacitor voltage vC to be the state variables. Applying KVL we get: '

CC vi;0'ivi)t(u ==+++− Thus,

)t(uivi

iv

C'

'C

+−−=

=

Finally we get,

[ ] [ ] )t(u0i

v10)t(i;)t(u

10

iv

1110

iv CCC +⎥

⎤⎢⎣

⎡=⎥

⎤⎢⎣

⎡+⎥⎦

⎤⎢⎣

⎡⎥⎦

⎤⎢⎣

⎡−−

=⎥⎥⎦

⎢⎢⎣

1F

+ −

u(t)

1H

i(t)

Page 67: Solucionario Capitulo 16 Sadiku

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.

Chapter 16, Problem 44. Develop the state equations for Prob. 16.2. Chapter 16, Solution 44.

First select the inductor current iL and the capacitor voltage vC to be the state variables. Applying KCL we get:

LCxxLC'C

C'C

Cx

x'L

xL'C

'Cx

L

i3333.1v3333.0vor;v2i4v2

vv

8v

4vv

v)t(u4i

v4i8vor;08

v2

vi

+=−+=+=+=

−=

−==++−

LC

'L

LCLCL'C

i3333.1v3333.0)t(u4i

i666.2v3333.1i333.5v3333.1i8v

−−=

+−=−−=

Now we can write the state equations.

⎥⎦

⎤⎢⎣

⎡⎥⎦

⎤⎢⎣

⎡=⎥

⎤⎢⎣

⎡+⎥

⎤⎢⎣

⎡⎥⎦

⎤⎢⎣

⎡−−

−=

⎥⎥⎦

⎢⎢⎣

L

Cx

L

C'L

'C

iv

3333.13333.0

v;)t(u40

iv

3333.13333.0666.23333.1

iv

4Ω +

vx

1H 1/8 F

)t(u4

+ − 2Ω

Page 68: Solucionario Capitulo 16 Sadiku

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.

Chapter 16, Problem 45. Develop the state equations for the circuit shown in Fig. 16.70.

Figure 16.70 For Prob. 16.45. Chapter 16, Solution 45.

First select the inductor current iL (current flowing left to right) and the capacitor voltage vC (voltage positive on the left and negative on the right) to be the state variables. Applying KCL we get:

2o'L

oL'CL

o'C

vvi

v2i4vor0i2

v4

v

−=

+==++−

1Co vvv +−=

21C

'L

1CL'C

vvvi

v2v2i4v

−+−=

+−=

[ ] [ ] ⎥⎦

⎤⎢⎣

⎡+⎥⎦

⎤⎢⎣

⎡−=⎥

⎤⎢⎣

⎡⎥⎦

⎤⎢⎣

⎡ −+⎥⎦

⎤⎢⎣

⎡⎥⎦

⎤⎢⎣

⎡−−

=⎥⎥⎦

⎢⎢⎣

⎡′

)t(v)t(v

01vi

10)t(v;)t(v)t(v

0211

vi

2410

vi

2

1

C

Lo

2

1

C

L

C

L

Page 69: Solucionario Capitulo 16 Sadiku

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.

Chapter 16, Problem 46. Develop the state equations for the circuit shown in Fig. 16.71.

Figure 16.71 For Prob. 16.46. Chapter 16, Solution 46.

First select the inductor current iL (left to right) and the capacitor voltage vC to be the state variables. Letting vo = vC and applying KCL we get:

sC'L

sLC'Cs

C'CL

vvi

iiv25.0vor0i4

vvi

+−=

++−==−++−

Thus,

⎥⎦

⎤⎢⎣

⎡⎥⎦

⎤⎢⎣

⎡+⎥

⎤⎢⎣

⎡⎥⎦

⎤⎢⎣

⎡=⎥

⎤⎢⎣

⎡⎥⎦

⎤⎢⎣

⎡+

⎥⎥⎦

⎢⎢⎣

⎡⎥⎦

⎤⎢⎣

⎡−

−=

⎥⎥⎦

⎢⎢⎣

s

s

L

Co

s

s'L

'C

'L

'C

iv

0000

iv

01

)t(v;iv

0110

iv

01125.0

iv

Page 70: Solucionario Capitulo 16 Sadiku

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.

Chapter 16, Problem 47. Develop the state equations for the circuit shown in Fig. 16.72.

Figure 16.72 For Prob. 16.47.

Page 71: Solucionario Capitulo 16 Sadiku

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.

Chapter 16, Solution 47.

First select the inductor current iL (left to right) and the capacitor voltage vC (+ on the left) to be the state variables.

Letting i1 = 4

v'C and i2 = iL and applying KVL we get:

Loop 1:

1CL'CL

'C

C1 v2v2i4vor0i4

v2vv +−==

⎟⎟

⎜⎜

⎛−++−

Loop 2:

21C21CL

L'L

2'L

'C

L

vvvv2

v2v2i4i2i

or0vi4

vi2

−+−=−+−

+−=

=++⎟⎟

⎜⎜

⎛−

1CL1CL

1 v5.0v5.0i4

v2v2i4i +−=

+−=

⎥⎦

⎤⎢⎣

⎡⎥⎦

⎤⎢⎣

⎡+⎥⎦

⎤⎢⎣

⎡⎥⎦

⎤⎢⎣

⎡ −=⎥

⎤⎢⎣

⎡⎥⎦

⎤⎢⎣

⎡⎥⎦

⎤⎢⎣

⎡ −+⎥

⎤⎢⎣

⎡⎥⎦

⎤⎢⎣

⎡−−

=⎥⎥⎦

⎢⎢⎣

⎡′

)t(v)t(v

0005.0

vi

015.01

)t(i)t(i

;)t(v)t(v

0211

vi

2410

vi

2

1

C

L

2

1

2

1

C

L

C

L

Page 72: Solucionario Capitulo 16 Sadiku

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.

Chapter 16, Problem 48. Develop the state equations for the following differential equation.

2

2 )(dt

tyd + dt

tdy )(4 + 3y(t) = z(t)

Chapter 16, Solution 48. Let x1 = y(t). Thus, )t(zx4x3yxandxyx 21

'22

''1 +−−=′′===

This gives our state equations.

[ ] [ ] )t(z0xx

01)t(y;)t(z10

xx

4310

xx

2

1

2

1'2

'1 +⎥

⎤⎢⎣

⎡=⎥

⎤⎢⎣

⎡+⎥

⎤⎢⎣

⎡⎥⎦

⎤⎢⎣

⎡−−

=⎥⎥⎦

⎢⎢⎣

Chapter 16, Problem 49. * Develop the state equations for the following differential equation.

2

2 )(dt

tyd + dt

tdy )(5 + 6y(t) = dt

tdz )( z(t)

* An asterisk indicates a challenging problem. Chapter 16, Solution 49.

zxyorzyzxxand)t(yxLet 2'''

121 +=−=−== Thus, z3x5x6zz2z)zx(5x6zyx 21

''21

''2 −−−=−+++−−=−′′=

This now leads to our state equations,

[ ] [ ] )t(z0xx

01)t(y;)t(z3

1xx

5610

xx

2

1

2

1'2

'1 +⎥

⎤⎢⎣

⎡=⎥

⎤⎢⎣

⎡−

+⎥⎦

⎤⎢⎣

⎡⎥⎦

⎤⎢⎣

⎡−−

=⎥⎥⎦

⎢⎢⎣

Page 73: Solucionario Capitulo 16 Sadiku

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.

Chapter 16, Problem 50. * Develop the state equations for the following differential equation.

3

3 )(dt

tyd + 2

2 )(6dt

tyd + dt

tdy )(11 + 6y(t) = z(t)

* An asterisk indicates a challenging problem. Chapter 16, Solution 50. Let x1 = y(t), x2 = .xxand,x '

23'1 =

Thus, )t(zx6x11x6x 321

"3 +−−−=

We can now write our state equations.

[ ] [ ] )t(z0xxx

001)t(y;)t(z100

xxx

6116100010

xxx

3

2

1

3

2

1

'3

'2

'1

+⎥⎥⎥

⎢⎢⎢

⎡=

⎥⎥⎥

⎢⎢⎢

⎡+

⎥⎥⎥

⎢⎢⎢

⎥⎥⎥

⎢⎢⎢

−−−=

⎥⎥⎥⎥

⎢⎢⎢⎢

Page 74: Solucionario Capitulo 16 Sadiku

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.

Chapter 16, Problem 51. * Given the following state equation, solve for y(t):

.x = ⎥

⎤⎢⎣

⎡−−

0244

x+ ⎥⎦

⎤⎢⎣

⎡20

u(t)

y(t) = [ ]01 x

* An asterisk indicates a challenging problem. Chapter 16, Solution 51. We transform the state equations into the s-domain and solve using Laplace transforms.

⎟⎠⎞

⎜⎝⎛+=−

s1B)s(AX)0(x)s(sX

Assume the initial conditions are zero.

⎥⎦

⎤⎢⎣

⎡⎥⎦

⎤⎢⎣

⎡+++

=⎟⎠⎞

⎜⎝⎛⎥⎦

⎤⎢⎣

⎡⎥⎦

⎤⎢⎣

⎡ −+=

⎟⎠⎞

⎜⎝⎛=−

)s/2(0

4s24s

8s4s1

s1

20

s244s

)s(X

s1B)s(X)AsI(

2

1

222222

221

2)2s(2

2)2s()2s(

s1

2)2s(4s

s1

8s4s4s

s1

)8s4s(s8)s(X)s(Y

++

−+

++

+−+=

++

−−+=

++

−−+=

++==

y(t) = ( )( ) )t(ut2sint2cose1 t2 +− −

Page 75: Solucionario Capitulo 16 Sadiku

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.

Chapter 16, Problem 52. * Given the following state equation, solve for y 1 (t).

.x = ⎥

⎤⎢⎣

⎡−−−

4212

x + ⎥⎦

⎤⎢⎣

⎡0411

⎥⎦

⎤⎢⎣

⎡)(2

)(tu

tu

y = ⎥⎦

⎤⎢⎣

⎡−−−

0122

x + ⎥⎦

⎤⎢⎣

⎡−1002

⎥⎦

⎤⎢⎣

⎡)(2

)(tu

tu

* An asterisk indicates a challenging problem. Chapter 16, Solution 52. Assume that the initial conditions are zero. Using Laplace transforms we get,

⎥⎦

⎤⎢⎣

⎡⎥⎦

⎤⎢⎣

⎡+−+

++=⎥

⎤⎢⎣

⎡⎥⎦

⎤⎢⎣

⎡⎥⎦

⎤⎢⎣

⎡+−

+=

s/4s/3

2s214s

10s6s1

s/2s/1

0411

4s212s

)s(X 2

1

222211)3s(8.1s8.0

s8.0

)1)3s((s8s3X

++

−−+=

++

+=

2222 1)3s(16.

1)3s(3s8.0

s8.0

+++

++

+−=

)t(u)tsine6.0tcose8.08.0()t(x t3t3

1−− +−=

222221)3s(4.4s4.1

s4.1

1)3s((s14s4X

++

−−+=

++

+=

2222 1)3s(12.0

1)3s(3s4.1

s4.1

++−

++

+−=

)t(u)tsine2.0tcose4.14.1()t(x t3t3

2−− −−=

)t(u)tsine8.0tcose4.44.2(

)t(u2)t(x2)t(x2)t(yt3t3

211−− −+−=

+−−=

)t(u)tsine6.0tcose8.02.1()t(u2)t(x)t(y t3t312

−− +−−=−=

Page 76: Solucionario Capitulo 16 Sadiku

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.

Chapter 16, Problem 53. Show that the parallel RLC circuit shown in Fig. 16.73 is stable.

Figure 16.73 For Prob. 16.53. Chapter 16, Solution 53. If oV is the voltage across R, applying KCL at the non-reference node gives

oo

oo

s VsL1

sCR1

sLV

VsCRV

I ⎟⎠⎞

⎜⎝⎛

++=++=

RLCsRsLIsRL

sL1

sCR1

IV 2

sso ++

=++

=

RsLRLCsIsL

RV

I 2so

o ++==

LC1RCssRCs

RsLRLCssL

II

)s(H 22s

o

++=

++==

The roots

LC1

)RC2(1

RC21-

s 22,1 −±=

both lie in the left half plane since R, L, and C are positive quantities. Thus, the circuit is stable.

Page 77: Solucionario Capitulo 16 Sadiku

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.

Chapter 16, Problem 54. A system is formed by cascading two systems as shown in Fig. 16.74. Given that the impulse response of the systems are

h 1 (t)= 3e t− u(t), h 2 (t) = e t4− u(t)

(a) Obtain the impulse response of the overall system. (b) Check if the overall system is stable.

Figure 16.74 For Prob. 16.54. Chapter 16, Solution 54.

(a) 1s

3)s(H1 += ,

4s1

)s(H2 +=

)4s)(1s(3

)s(H)s(H)s(H 21 ++==

[ ] ⎥⎦⎤

⎢⎣⎡

++

+==

4sB

1sA

)s(H)t(h 1-1- LL

1A = , 1-B =

=)t(h )t(u)ee( -4t-t −

(b) Since the poles of H(s) all lie in the left half s-plane, the system is stable.

Page 78: Solucionario Capitulo 16 Sadiku

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.

Chapter 16, Problem 55. Determine whether the op amp circuit in Fig. 16.75 is stable.

Figure 16.75 For Prob. 16.55. Chapter 16, Solution 55. Let 1oV be the voltage at the output of the first op amp.

sRC1

RsC1

VV

s

1o −=

−= ,

sRC1

VV

1o

o −=

222s

o

CRs1

VV

)s(H ==

22CRt

)t(h =

∞=

∞→)t(hlim

t, i.e. the output is unbounded.

Hence, the circuit is unstable.

Page 79: Solucionario Capitulo 16 Sadiku

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.

Chapter 16, Problem 56. It is desired to realize the transfer function

)()(

1

2

sVsV =

622

2 ++ sss

using the circuit in Fig. 16.76. Choose R = 1 kΩ and find L and C.

Figure 16.76 For Prob. 16.56. Chapter 16, Solution 56.

LCs1sL

sC1

sL

sC1

sL

sC1

||sL 2+=

+

⋅=

RsLRLCssL

LCs1sL

R

LCs1sL

VV

2

2

2

1

2

++=

++

+=

LC1

RC1

ss

RC1

s

VV

21

2

+⋅+

⋅=

Comparing this with the given transfer function,

RC1

2 = , LC1

6 =

If Ω= k1R , ==R21

C F500 µ

==C61

L H3.333

Page 80: Solucionario Capitulo 16 Sadiku

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.

Chapter 16, Problem 57.

Design an op amp circuit, using Fig. 16.77, that will realize the following transfer function:

)()(0

sVsV

i

= -)000,4(2

000,1++

ss

Choose C 1 =10 ;Fµ determine R 1 , R 2 , and C 2

Figure 16.77 For Prob. 16.57.

Page 81: Solucionario Capitulo 16 Sadiku

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.

Chapter 16, Solution 57. The circuit is transformed in the s-domain as shown below.

1/sC2 1/sC1 R2 Vi – Vo R1 +

Let 1

111 1

1 1 11

1

11// 1 1

RRsCZ R

sC sR CRsC

= = =++

222

2 22 2 2

22

11// 1 1

RRsCZ R

sC sR CRsC

= = =++

This is an inverting amplifier.

2

2 2 1 1 12 2 1 1 1 1

11 1 2 2 2

1 1 2 2 2 2

1 11( ) 1 11

o

i

R s sZ R R C CsR C R C R CVH s V RZ R R C Cs s

sR C R C R C

⎡ ⎤ ⎡ ⎤− + +⎢ ⎥ ⎢ ⎥−+⎢ ⎥ ⎢ ⎥= = − = = − =⎢ ⎥ ⎢ ⎥+ +⎢ ⎥ ⎢ ⎥+ ⎣ ⎦ ⎣ ⎦

Comparing this with ( 1000)( )

2( 4000)sH ss+

= −+

we obtain: 1

2 12

1/ 2 2 20C C C FC

µ= ⎯⎯→ = =

1 3 61 1 1

1 1 11000 1001000 10 10 10

RR C C x x −= ⎯⎯→ = = = Ω

2 3 62 2 2

1 1 14000 12.84000 4 10 20 10

RR C C x x x −= ⎯⎯→ = = = Ω 12.5Ω

Page 82: Solucionario Capitulo 16 Sadiku

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.

Chapter 16, Problem 58. Realize the transfer function

)()(0

sVsV

s

= 10+s

s

using the circuit in Fig. 16.78. Let Y 1 = sC 1 , Y 2 = 1/R 1 , Y 3 = sC 2 . Choose R 1 = 1kΩ and determine C 1 and C 2 .

Figure 16.78 For Prob. 16.58. Chapter 16, Solution 58. We apply KCL at the noninverting terminal at the op amp.

)YY)(V0(Y)0V( 21o3s −−=−

o21s3 V)YY(-VY +=

21

3

s

o

YYY-

VV

+=

Let 11 sCY = , 12 R1Y = , 23 sCY =

11

12

11

2

s

o

CR1sCsC-

R1sCsC-

VV

+=

+=

Comparing this with the given transfer function,

1CC

1

2 = , 10CR

1

11=

If Ω= k1R1 ,

=== 421 101

CC F100 µ

Page 83: Solucionario Capitulo 16 Sadiku

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.

Chapter 16, Problem 59. Synthesize the transfer function

)()(0

sVsV

in

= 62

6

1010010

++ ss

using the topology of Fig. 16.79. Let Y 1 = 1/ 1R , Y 2 = 1/R 2 , Y 3 = sC 1 , Y 4 sC 2 . Choose R 1 = 1kΩ and determine C 1 , C 2 , and R 2 .

Figure 16.79 For Prob. 16.59. Chapter 16, Solution 59. Consider the circuit shown below. We notice that o3 VV = and o32 VVV == .

−+ Vo

+ −

Vin

V2

V1

Y1 Y2

Y4

Y3

Page 84: Solucionario Capitulo 16 Sadiku

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.

At node 1, 4o12o111in Y)VV(Y)VV(Y)VV( −+−=−

)YY(V)YYY(VYV 42o42111in +−++= (1) At node 2,

3o2o1 Y)0V(Y)VV( −=−

o3221 V)YY(YV +=

o2

321 V

YYY

V+

= (2)

Substituting (2) into (1),

)YY(VV)YYY(Y

YYYV 42oo421

2

321in +−++⋅

+=

)YYYYYYYYYYYYYY(VYYV 422243323142

2221o21in −−+++++=

43323121

21

in

o

YYYYYYYYYY

VV

+++=

1Y and 2Y must be resistive, while 3Y and 4Y must be capacitive.

Let 1

1 R1

Y = , 2

2 R1

Y = , 13 sCY = , 24 sCY =

212

2

1

1

1

21

21

in

o

CCsRsC

RsC

RR1

RR1

VV

+++=

2121221

212

2121

in

o

CCRR1

CRRRR

ss

CCRR1

VV

+⎟⎠

⎞⎜⎝

⎛ +⋅+

=

Choose Ω= k1R1 , then

6

212110

CCRR1

= and 100CRRRR

221

21 =+

We have three equations and four unknowns. Thus, there is a family of solutions. One such solution is

=2R Ωk1 , =1C nF50 , =2C F20 µ

Page 85: Solucionario Capitulo 16 Sadiku

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.

Chapter 16, Problem 60. Obtain the transfer function of the op amp circuit in Fig. 16.80 in the form of

)()(0

sVsV

i

= cbss

as++2

where a, b, and c are constants. Determine the constants.

Figure 16.80 For Prob. 16.67.

Page 86: Solucionario Capitulo 16 Sadiku

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.

Chapter 16, Solution 60. With the following MATLAB codes, the Bode plots are generated as shown below. num=[1 1]; den= [1 5 6]; bode(num,den);

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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.

Chapter 16, Problem 61. A certain network has an input admittance Y(s). The admittance has a pole at s = -3, a zero at s = -1, and Y(∞ ) = 0.25 S. (a) Find Y(s). (b) An 8-V battery is connected to the network via a switch. If the switch is closed at t = 0, find the current i(t) through Y(s) using the Laplace transform. Chapter 16, Solution 61. We use the following codes to obtain the Bode plots below. num=[1 4]; den= [1 6 11 6]; bode(num,den);

Page 88: Solucionario Capitulo 16 Sadiku

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.

Chapter 16, Problem 62.

A gyrator is a device for simulating an inductor in a network. A basic gyrator circuit is shown in Fig. 16.81. By finding V i (s)/I 0 (s), show that the inductance produced by the gyrator is L = CR 2 .

Figure 16.81 For Prob. 16.69. Chapter 16, Solution 62. The following codes are used to obtain the Bode plots below. num=[1 1]; den= [1 0.5 1]; bode(num,den);