Introduction to Electric Circuits

Answers 245

and each successive negative voltage becoming numerically larger.

10. i(t) = (2/to) exp (-at) sin tot where a = r/EL = 155 s and
    to = ~/[(1/CL) - (R/EL) E] = 1.73 • 105 rad s -1. This is an exptgnentially decaying sine wave
    and is underdamped.

Chapter 9

Self-assessment test

3. A four-terminal network. 4. Because they are measured with either the input or the
   output port on open circuit. 5. The admittance (y) parameters. 6. For the analysis of
   transistor circuits. 7. g-parameters. 8. Transmission parameters. 9. The input and output
   ports may be interchanged without effect. 10. A and D. 15. V/(B/C). 16. V'(ZocZsc).


4. 20 lOgl0 (Ib/Ia) dB where Ib is the load current before insertion and Ia is the load current
   after insertion.

Problems

1. (a) Zll = 1200 •, z12 = ZE1 = z22 = 900 •; (b) Yll = (1/300) S, Y12 = Y21 = (-1/300) S,
   Y22 = (4/900) S. 2. (a) Zll = 1200 II, z12 = zE1 = 900 12, z22 = 150012, (b) Yl1 -- (5/3300) S,
   Y12 = Y21 = (-1/1100) S, Y22 = (4/3300) S. 3. (a) -83, (b) -91.4. gll "-" 10-3 S, gl2 -- 103,
   gEl -- 10-2, g22 "-" 10 k~"~. 5. A = D = 0.95/0.78 ~ B = 95/__75 ~ fl, C = 1.01/_90.4 ~ S. 6.
   A = 0.986/__0.78 ~ B = 7.06/-66.7 ~ f~, C = 0.01/-80 ~ S, D = 0.957/-1.5 ~ 7. Z = D = 17/8,
   B = (4500/8) 12, C = (5/800) S. 8. 775 fl. 10. (a) Z = 5/3, B = 1600 12, C = (1/600) S,
   D = 2; (b) Zll = 895 12; Z12 = 1072 fl. 11. -6.4 dB. 12. (a) 13 dB; (b) 9.5 dB. 13. (a) 580 12;
   (b) j684 12.

Chapter 10

Self-assessment test

1. Current. 2. I = VY. 3. (LI2)/2.4. A resistor and an inductor in series. 5. Thevenin's
   Theorem. 6. Permeability. 7. Current density. 8. Magnetic flux. 9. F(=NI) = S.
   IO. G = A tr/d. 11. 'Voltage cannot change instantaneously in a capacitor'. 12. Compliance.


2. I = GV. 14. Vc = V[1 - exp (-t/cg)].