45 for prob 247 obtain the equivalent resistance rab

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Unformatted text preview: orkbook Contents CHAPTER 2 2.45 Basic Laws a What value of R in the circuit of Fig. 2.109 would cause the current source to deliver 800 mW to the resistors? R 69 R R b 30 mA (b) R R Figure 2.111 ∗ Figure 2.109 2.46 2.48 For Prob. 2.45. For Prob. 2.47. Obtain the equivalent resistance Rab in each of the circuits of Fig. 2.112. In (b), all resistors have a value of 30 . Obtain the equivalent resistance at the terminals a -b for each of the circuits in Fig. 2.110. 30 Ω 20 Ω a 10 Ω 30 Ω 10 Ω 10 Ω a 20 Ω 10 Ω 60 Ω 20 Ω 40 Ω 50 Ω 80 Ω b b (a) (a) a 30 Ω 30 Ω 25 Ω 10 Ω 20 Ω a 5Ω b 15 Ω (b) b Figure 2.112 (b) Figure 2.110 ∗ 2.47 For Prob. 2.46. 2.49 For Prob. 2.48. Calculate Io in the circuit of Fig. 2.113. Find the equivalent resistance Rab in each of the circuits of Fig. 2.111. Each resistor is 100 . Io a 20 Ω 24 V + − 60 Ω 40 Ω 10 Ω 50 Ω 20 Ω b (a) | For Prob. 2.49. asterisk indicates a challenging problem. v v ∗ An Figure 2.113 | e-Text Main Menu | Textbook Table of Contents | Problem Solving Workbook Contents 70 PART 1 2.50 DC Circuits Determine V in the circuit of Fig. 2.114. I 30 Ω 16 Ω + V − + − 100 V 40 W 50 W + − 100 V 15 Ω 30 W 10 Ω 35 Ω 12 Ω Figure 2.117 20 Ω For Prob. 2.53. 2.51 As a design engineer, you are asked to design a lighting system consisting of a 70-W power supply and two lightbulbs as shown in Fig. 2.118. You must select the two bulbs from the following three available bulbs. For Prob. 2.50. Find Req and I in the circuit of Fig. 2.115. I R1 = 80 , cost = $0.60 (standard size) R2 = 90 , cost = $0.90 (standard size) R3 = 100 , cost = $0.75 (nonstandard size) 2Ω 4Ω 1Ω 6Ω The system should be designed for minimum cost such that I = 1.2 A ± 5 percent. 12 Ω I 20 V 8Ω + − 2Ω + 70 W Power Supply 4Ω 3Ω 10 Ω Figure 2.118 Req Figure 2.115 Section 2.8 2.52 If an ammeter with an internal resistance of 100 and a current capacity of 2 mA is to measure 5 A, determine the value of th...
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This note was uploaded on 07/16/2012 for the course KA KA 2000 taught by Professor Bkav during the Spring '12 term at Cambridge.

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