Unformatted text preview: +
vo
− 9000
(30 A) = 10 mA
9000 + 18,000 i2 io 30 mA po = vo io = 180(30) mW = 5.4 W
resistor is i1 +
vo
− 9 kΩ 18 kΩ (b) 2
p = iv = i2 (i2 R) = i2 R = (10 × 10−3 )2 (12,000) = 1.2 W Power absorbed by the 6k 12 kΩ (a) Notice that the voltage across the 9k and 18k resistors is the same,
and vo = 9,000i1 = 18,000i2 = 180 V, as expected.
(b) Power supplied by the source is (c) Power absorbed by the 12k 9 kΩ Figure 2.44 resistor is For Example 2.13:
(a) original circuit,
(b) its equivalent circuit. 2
p = i2 R = (10 × 10−3 )2 (6000) = 0.6 W Power absorbed by the 9k
p= resistor is
2
(180)2
vo
=
= 3.6 W
R
9000 or
p = vo i1 = 180(20) mW = 3.6 W
Notice that the power supplied (5.4 W) equals the power absorbed (1.2 +
0.6 + 3.6 = 5.4 W). This is one way of checking results. PRACTICE PROBLEM 2.13
For the circuit shown in Fig. 2.45, ﬁnd: (a) v1 and v2 , (b) the power dissipated in the 3k and 20k resistors, and (c) the power supplied by
the current source.
1 kΩ 3 kΩ +
v1
− Figure 2.45 10 mA 5 kΩ +
v2
− 20 kΩ For Practice Prob. 2.13. Answer: (a) 15 V, 20 V, (b) 75 mW, 20 mW, (c) 200 mW. @
 v v Network Analysis  eText Main Menu  Textbook Table of Contents  Problem Solving Workbook Contents 50 PART 1
†
R1 R2 R3
R4 vs +
−
R5 Figure 2.46 R6 The bridge network. DC Circuits 2.7 WYEDELTA TRANSFORMATIONS Situations often arise in circuit analysis when the resistors are neither in
parallel nor in series. For example, consider the bridge circuit in Fig.
2.46. How do we combine resistors R1 through R6 when the resistors
are neither in series nor in parallel? Many circuits of the type shown in
Fig. 2.46 can be simpliﬁed by using threeterminal equivalent networks.
These are the wye (Y) or tee (T) network shown in Fig. 2.47 and the
delta ( ) or pi ( ) network shown in Fig. 2.48. These networks occur by
themselves or as part of a larger network. They are used in threephase
networks, electrical ﬁlters, and matching networks. Our main interest
here is in...
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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.
 Spring '12
 bkav

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