# Sol-Ch28 - Exercises 1. V b a = Ir : 9.5 = (9.5/4)r, 10 =...

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Unformatted text preview: Exercises 1. V b a = Ir : 9.5 = (9.5/4)r, 10 = (10/6) r r = 0.706 , =11.2 V 2. = 12.4, thus 11.2 = 12.4 80r, thus r = 0.015 3. 8.4 = 6r; 7.2 = 8r. Thus = 12 v, r = 0.6 4. 8 = /R; 6 = /(R + 2). Thus, R = 6 , = 48 V 5. (a) P = [V/(R + r)] 2 R, so 50 = 256 4/(4 + r) 2 , thus r = 0.525 (b) 100 = 256R/(R + 0.525) 2 , so R 2 =1.51R + 0.276 = 0 R = 0.215 , 1.295 6. (a) I = (14.2 12.4)/0.05 = 36 A, P = I 2 R = 64.8 W (b) (36 A) (12.4 V) = 446 W 7. R = V 2 /P = (11.2 V) 2 /(50 W) = 2.51 , I = (P/R) 1/2 = 4.46 A V b a = 11.2 = 12 94.46)r, r =0.18 8. (a) P = 100R/(R + 1) 2 : 1.25 P = 100(1.5R)/(1.5R + 1) 2 , thus R = 0.236 (b) 0.75P = 100 (1.5 R)/(1.5R + 1) 2 , thus R = 4.83 9. (a) 7.82 ; (b) I o = 1.28 A and I 1 = 4.4I 2 , so I 2 = 1.28/5.4 = 0.237 A and I 1 = 1.043 A. Find V 1 = 1.043 V; V 2 = 0.474 V. Finally, V 4 = V 1 V 2 = 0.569 V 10. 4R/3 = 16 , thus R = 12 11. 2 , 3 , 4 , 5 , 6 , 7 , 8 , 9 , 6/5 , 4/3 , 12/7 , 12/13, 26/7 , 13/3 , 26/5 , 20/9 , 14.9 12. Two in series, then placed in parallel. CHAPTER 28 Twoin parallel, then placed in series. 13. 1 , 2 , 3 , 4; 1 , 2 , 4 , 5 1 , 2 , 3 , 5; 1 , 2 , 4 , 4 . 14. V b a = 1 I 1 r 1 = 2 = I 2 r 2 , also I 1 = I 2 . Find I 1 = ( 1 2 ) / (r 2 + r 2 ) = 0.25 A, thus V b a = 1.52 V P = (0.25) 2 (0.2) = 12.5 mW 15. I = P/V : 0.5 A, 0.083 A, 8.33 A; 12.5 A 16. (a) V = (PR) 1/2 = 7.07 V for each, so 21.2 V for three in series; (b) 7.07 V 17. (a) V = (PR) 1/2 = 8.94 V for each, so 8.94 V; (b) I = 8.94 V/4 = 2.236 A through single R, and 1.118 A through each R in parallel. Thus V = 1.118 4 + 8.94 = 13.4 V 18. (a) R e q = 2 + 3R 2 /(3 + R 2 ), but ( 1 2 ) = (2A) R e q , thus R e q = 3 . Solve to find R 2 = 1.5 (b) P 1 = 1.33 W; P 2 = 2.66 W (c) V 1 = 10 V, V 2 = 8V (b) P 1 = I 1 = 24 W, P 2 = I 2 = 12 W 19. (a) 0.5 A; (b) P 1 = 0.5 W, P 2 = 1 W; (c) 4.5 W, 3 W 20. (a) I = 1 A, so V p = 1 + Ir 1 = 6V (b) V 1 = 1 + Ir 1 = 6V, V 2 = 2 Ir 2 = 7.5 V (c) P = I 2 R = 1.5 W 21. I 7 = 0 ; I 3 = 3.33 A; I 4 =2.5 A 22. I 2 = 2A; V 2 + 4 = 12 V, thus R = 6 . Circuit is equivalent to three 3 resistors in parallel with 1 in series, thus for whole circuit R e q = 2 The current in each 3 branch is 4 A, thus I t o t = 12 A. Finally, = I t o t R e q = 24 V 23. (I/2)r IR = 0, so I = /(R + r/2) P = I 2 R = 2 R/(R + r/2) 2 . Set dP/dR = 0 to find R = r/2 24. R e q = R 1 + R 2 R L /(R 2 + R L ); I = V/R e q , and I L = IR 2 /(R 2 + R L ) P L = I 1 2 R...
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## This note was uploaded on 11/09/2011 for the course EE EE taught by Professor Ee during the Spring '11 term at National Chiao Tung University.

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Sol-Ch28 - Exercises 1. V b a = Ir : 9.5 = (9.5/4)r, 10 =...

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