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Unformatted text preview: e resistance needed.
Calculate the power dissipated in the shunt resistor. 2.57 The potentiometer (adjustable resistor) Rx in Fig.
2.119 is to be designed to adjust current ix from 1 A
to 10 A. Calculate the values of R and Rx to achieve
this. Applications ix 40 Ω
− Bulb Figure 2.116 110 V +
− 80 Ω Figure 2.119 For Prob. 2.52. 2.58
2.53 Three lightbulbs are connected in series to a 100-V
battery as shown in Fig. 2.117. Find the current I
through the bulbs. v | | For Prob. 2.55. 2.56 For Prob. 2.51. The lightbulb in Fig. 2.116 is rated 120 V, 0.75 A.
Calculate Vs to make the lightbulb operate at the
rated conditions. Vs Ry Rx − 5Ω v ∗ If the three bulbs of Prob. 2.53 are connected in
parallel to the 100-V battery, calculate the current
through each bulb. 2.55 Figure 2.114 2.54 e-Text Main Menu R
ix For Prob. 2.57. A d’Arsonval meter with an internal resistance of 1
k requires 10 mA to produce full-scale deﬂection.
Calculate the value of a series resistance needed to
measure 50 V of full scale. | Textbook Table of Contents | Problem Solving Workbook Contents CHAPTER 2
2.59 2.60 A 20-k /V voltmeter reads 10 V full scale.
(a) What series resistance is required to make the
meter read 50 V full scale?
(b) What power will the series resistor dissipate
when the meter reads full scale?
(a) Obtain the voltage vo in the circuit of Fig.
(b) Determine the voltage vo measured when a
voltmeter with 6-k internal resistance is
connected as shown in Fig. 2.120(b).
(c) The ﬁnite resistance of the meter introduces an
error into the measurement. Calculate the
percent error as Basic Laws i' 16 Ω 40 Ω Figure 2.121
2.62 For Prob. 2.61.
A voltmeter is used to measure Vo in the circuit in
Fig. 2.122. The voltmeter model consists of an ideal
voltmeter in parallel with a 100-k resistor. Let
Vs = 40 V, Rs = 10 k , and R1 = 20 k . Calculate
Vo with and without the voltmeter when
(a) R2 = 1 k
(b) R2 = 10 k
(c) R2 = 100 k
Rs 1 kΩ
4 kΩ +
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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