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ETEC 3501
Chapter 3 – Part 1
Simple Resistive Circuits
3.1 Resistors in Series
•
For a series circuit shown in Figure 3.1, the series current is
the same throughout the circuit.
•
Applying KVL around the loop shown in Figure 3.2 yields:
•
From Equation 3.3, the total series resistance can be
represented by summing the values of all individual resistances.
Figure 3.1 Decision-making tree: transferring to a higher level of care.
Electric Circuits, Ninth Edition
James W. Nilsson • Susan A. Riedel
Copyright ©2011, ©2008, ©2005 by Pearson Education, Inc.
Upper Saddle River, New Jersey 07458
All rights reserved.
Figure 3.2 Series resistors with a single unknown current is.
Electric Circuits, Ninth Edition
James W. Nilsson • Susan A. Riedel
Copyright ©2011, ©2008, ©2005 by Pearson Education, Inc.
Upper Saddle River, New Jersey 07458
All rights reserved.
Figure 3.3 A simplified version of the circuit shown in Fig. 3.2.
Electric Circuits, Ninth Edition
James W. Nilsson • Susan A. Riedel
Copyright ©2011, ©2008, ©2005 by Pearson Education, Inc.
Upper Saddle River, New Jersey 07458
All rights reserved.
Figure 3.4 The black box equivalent of the circuit shown in Fig. 3.2.
Electric Circuits, Ninth Edition
James W. Nilsson • Susan A. Riedel
Copyright ©2011, ©2008, ©2005 by Pearson Education, Inc.
Upper Saddle River, New Jersey 07458
All rights reserved.
3.2 Resistors in Parallel
•
Using KCL, total parallel resistance can be determined as
follows:
Figure 3.5 Resistors in parallel.
Electric Circuits, Ninth Edition
James W. Nilsson • Susan A. Riedel
Copyright ©2011, ©2008, ©2005 by Pearson Education, Inc.
Upper Saddle River, New Jersey 07458
All rights reserved.
Figure 3.6 Nonparallel resistors.
Electric Circuits, Ninth Edition
James W. Nilsson • Susan A. Riedel
Copyright ©2011, ©2008, ©2005 by Pearson Education, Inc.
Upper Saddle River, New Jersey 07458
All rights reserved.
•
Review example 3.1, analysis of Figure 3.9
Figure 3.7 Replacing the four parallel resistors shown in Fig. 3.5 with a single equivalent resistor.
Electric Circuits, Ninth Edition
James W. Nilsson • Susan A. Riedel
Copyright ©2011, ©2008, ©2005 by Pearson Education, Inc.
Upper Saddle River, New Jersey 07458
All rights reserved.
Figure 3.8 Two resistors connected in parallel.
Electric Circuits, Ninth Edition
James W. Nilsson • Susan A. Riedel
Copyright ©2011, ©2008, ©2005 by Pearson Education, Inc.
Upper Saddle River, New Jersey 07458
All rights reserved.
Figure 3.9 The circuit for Example 3.1.
Electric Circuits, Ninth Edition
James W. Nilsson • Susan A. Riedel
Copyright ©2011, ©2008, ©2005 by Pearson Education, Inc.
Upper Saddle River, New Jersey 07458
All rights reserved.
Example 3.1 – Applying Series-Parallel Simplification
•
Determine is , i1 , and i2 for the circuit below.
•
Combine the 3 and 6 Ohm resistors
•
Combine the 18 and 9 Ohm resistors
is = 120V / 10 Ohms = 12A
Assessment Problems
3.3 The Voltage-Divider and Current-Divider
Circuits
•
Voltage-divider rule can be defined by using KVL and Ohm’s
law on the circuit of Figure 3.12
•
Can be used as a cheap means to produce a lower voltage
(see Figure 3.13)
Figure 3.13 A voltage divider connected to a load RL.
Electric Circuits, Ninth Edition
James W. Nilsson • Susan A. Riedel
Copyright ©2011, ©2008, ©2005 by Pearson Education, Inc.
Upper Saddle River, New Jersey 07458
All rights reserved.
Example 3.2 – Analyzing a Voltage-Divider Circuit
•
Current-divider rule can be defined by using KCL and Ohm’s
law on the circuit of Figure 3.15
Example 3.3 – Analyzing a Current-Divider Circuit
Assessment Problems
3.4 Voltage Division and Current Division