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CHAPTER 2. NETWORKS 1: 0909201-01 16 September 2002 – Lecture 2a ROWAN UNIVERSITY College of Engineering Professor Peter Mark Jansson, PP PE DEPARTMENT OF ELECTRICAL & COMPUTER ENGINEERING Autumn Semester 2002. Networks I. Today’s Learning Objectives –

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CHAPTER 2

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## CHAPTER 2

NETWORKS 1: 0909201-01

16 September 2002 – Lecture 2a

ROWAN UNIVERSITY

College of Engineering

Professor Peter Mark Jansson, PP PE

DEPARTMENT OF ELECTRICAL & COMPUTER ENGINEERING

Autumn Semester 2002

### Networks I

• Today’s Learning Objectives –

• Define active and passive circuit elements

• Apply Ohm’s law (v=Ri, I=v/r, p=i2r, etc.)

• Analyze DC circuits with passive elements including: resistance

• Analyze independent and dependent electrical sources

### chapter 2 - overview

• engineering and linear models

• active and passive circuit elements

• resistors – Ohm’s Law

• independent sources

• dependent sources

• transducers

• switches

### models

• A model is an object or pattern of objects or an equation that represents an element or circuit.

• Some examples:

• model airplane

• person wearing designer clothes

• V = I * R

### circuit models

• in our work in Networks I we will construct models of elements that will be interconnected to form models of circuits. (while these will illuminate our understanding of the real thing, they are not the real thing)

### circuit analysis

• the purpose of making circuit models is so we can perform mathematical and theoretical analyses prior to making the real thing. the goal of circuit analysis is to predict the quantitative electrical behavior (voltage & current) of physical systems so we can explain the overall operation of the circuit.

### LINEARITY implies:

• SUPERPOSITION

• In a single element:

• if the application of

• i1yields v1and i2yields v2then:

• i1 + i2will yield v1 + v2

• HOMOGENEITY

• In a single element:

• if i1is multiplied by k (a constant) then:

• the application of ki1will yield kv1

### linearity is key to networks I

• we will only consider linear models of circuits in this course

• any device or element that does not satisfy both the principles of superposition and homogeneity is considered non-linear

### active & passive elements

• A passive element absorbs energy.

• What does it do with the energy?

• Would the power through this element be + or - ?

• Give an example of a passive element.

• An active element is capable of supplying energy.

• Where does it get the energy?

• Is the power + or - ?

• Give an example of an active element.

### resistance

• Property of an element or device that impedes the flow of current.

• And we have Ohm’s Law:

• Which came first?

### resistors

• A few things we need to know:

• R = 1/G (G is called conductance)

• If a resistor heats up, its resistance changes.

• The power absorbed by a resistor can be represented (modeled) two ways:

• p = vi = v(v/R) = v2/R or v2G

• p = vi = iRi = i2R or i2/G

• The energy delivered to a resistor is: