CHAPTER 1CHAPTER 1

NETWORKS 1: NETWORKS 1: 0909201-02/030909201-02/03 23 OCTOBER 2002

ROWAN UNIVERSITYROWAN UNIVERSITY

College of EngineeringCollege of Engineering

Professor Peter Mark Jansson, PP PEProfessor Peter Mark Jansson, PP PEDEPARTMENT OF ELECTRICAL & COMPUTER ENGINEERINGDEPARTMENT OF ELECTRICAL & COMPUTER ENGINEERING

Autumn Semester 2002 – Quarter TwoAutumn Semester 2002 – Quarter Two

Welcome to Networks I

Learning Objectives – Define circuit elements Analyze electrical circuits Apply circuit parameters (v, i, r, p, etc.) Analyze DC circuits with passive elements

including: resistance, energy storage (C,L) Build/Model circuits using Mentorgraphics,

Pspice, IMITS and MatLab

Learning Aids: Overview

Lectures – Rowan Auditorium

Laboratories – Rowan Hall Room 204/6

Two Lab Sections – M12.30-3.15, M3.30-6.15

Syllabus / Text (read ahead – ch. 1/2) Computer Tools Website Email

Learning Aids:

Required Text : Introduction to Electric Circuits 5th Edition Dorf and Svoboda

Website : http:www.engineering.rowan.edu/~jansson/

Check your Email regularly (daily)

Cruise course website

Website : http:www.engineering.rowan.edu/~jansson/

Learning Evaluation

Grades Tests (3 @ 20%), Assignments (40%) LECTURE:

In-Class, HW and Participation (20%) LABS:

Reports, HW, etc. (20%)

Section 1 – PC/Laptop Reqm’ts

Windows 9x, NT, 2000, Me or XP Pentium 233 MHz or faster 16 Mb RAM 255 Mb free disk space (required) 12X CD-ROM drive or better 16-bit Sound card or better 2 Mb Video card or better

chapter 1 – overview

history of electricity electric circuits and current flow systems of units voltage power and energy voltmeters and ammeters circuit analysis and design

Imagine a World with..

No internetNo cell phonesNo computersNo television or video gamesNo mass communication (radio, telephone)No tall buildings

Imagine a World with..

No electricityNo electronic devicesNo medical technologyNo appliances Refrigerators Microwaves Water heaters Air conditioning

No traffic controls

That world would be

PrimitiveDifficult to survive in A very hard life……

Electrical Engineers Transformed Society

Long, long ago in countries far, far away the journey began…..2367 BC – Hoang-Ti in China1110 BC – Tchi-nan designed600 BC – Etruscans control lightning250 BC – Flying Cupid in Diana’s temple658 AD – Japan’s first magnetic cars

Electrical Science Emerges

600 AD Attractive power of E-S materials1551Electricity and Magnetism defined1672Pointed Conductors 1720Grey’s Planetarium1746 Atmospheric Electricity discovered1814Electrical Spectrum detailed1821First Electric Motor

Electric Technology

1825 First Electromagnet1832 First E-M Induction Generator1837 Telegraph1879 First DC Power System1888 First AC Generator1895 X-rays Discovered1901 Radio

Quotable Quotes

Everything that can be invented has been invented Charles H. Duell - US Patent Office 1899

Heavier than air flying machines are impossible Lord Kelvin – Royal Society 1895

There is no likelihood man can ever tapthe power of the atom Robert Milliken Nobel Laureate Physics 1923

Discovery continues

AC Electric Grids 1900sFlourescent Lighting 1930sComputing – 1930sTelevision – 1940sPersonal Computing 1970sInternet – 199021st Century ?

electric circuits & current flow

An electric circuit is an interconnection of circuit elements linked together to form a closed path so that electric current may flow continuously

Battery Resistor

i1

Where is ground?

electric circuits & current flow

Current is the time rate of flow of electric charge (q) past a given pointUse lower case to indicate a time varying current and upper case to indicate a constant or direct current

i1 i2dt

dqi 21 ii

units

Systeme International d’UnitesBase Units (m, kg, s, A, K, mol, cd)Derived Units (J, W, C, V, Ω, S, F, Wb, H)

See text page 13 What are base units for Energy (J) and

Power (W)

voltageThe voltage across an element is the work (energy) required to move a unit positive charge from the - terminal to the + terminal.

a b

ba

+ vab -

- vba + baab vv dq

dwv

powerPower is the time rate of expending energy.Power absorbed by an element is positive, Power delivered by an element is negative.

a b

ba

+ vab -

- vba +

i

i

ivdt

dq

dq

dw

dt

dwp

passive sign convention (psc)

Positive current flows from positive voltage to negative voltage.

a b

- vab +i

ba

+ vab -

i

Is the current in

this resistor positive

or negative?

Is the current in

this element positive

or negative?

power and psc

p = v • i Power is absorbed by an element adhering to

the passive sign convention (sink)

Power is supplied by an element not adhering to the passive sign convention (source)

a b

+ vab -i

a b

- vab +i

power and energy

p = v • i power = voltage * current

energy = power * time

tpdt w0

electric circuits & current flow

Current is the time rate of flow of electric charge (q) past a given pointUse lower case to indicate a time varying current and upper case to indicate a constant or direct current

i1 i2dt

dqi 21 ii

voltageThe voltage across an element is the work (energy) required to move a unit positive charge from the - terminal to the + terminal.

a b

ba

+ vab -

- vba + baab vv dq

dwv

voltage / current analogy

mechanical system analogy: pump, fluid pressure (head), velocity battery, voltage, current

high pressure (head) high voltage increased fluid flow high current increasing either: increases power

circuit analogy envision a closed system of water flowing in troughs pumps elevate the head of the flow and increase its velocity in various troughs flow of mass is conserved energy can be added (pumps) or extracted (waterwheels) though overall system of water flow is conserved energy is transferred by head and velocity in a given part of circuit flowrate is constant

powerPower is the rate of expending energy.Power absorbed by an element is positive, Power delivered by an element is negative.

a b

ba

+ vab -

- vba +

i

i

ivdt

dq

dq

dw

dt

dwp

passive sign convention (psc)

positive current flows from positive voltage to negative voltage.

a b

- vab +i

ba

+ vab -

i

Is the current in

this resistor positive

or negative?

Is the current in

this element positive

or negative?

power and psc

p = v • i Power is absorbed by an element adhering to

the passive sign convention (sink)

Power is supplied by an element not adhering to the passive sign convention (source)

a b

+ vab -i

a b

- vab +i

power and psc example what is the power absorbed or supplied by the element below, when i = 4A?

power = 12V x 4A = 48 W does not adhere to passive sign convention,

so power is supplied.

a b

- vab = 12V +i

power and psc quiz what is the power absorbed or supplied by the element below, when i = 4A?

power = 12V x 4A = 48 Wdoes not adhere to passive sign convention,

so power is supplied.

a b

- vab = 12V +i

power and energy

p = v • i power = voltage * current power is the time rate of expending

energy

energy = power * time energy is the capacity to do work

tpdt w0

power and energy

energy = force x distance

power = energy / time period (secs)

power and energy example

a mass of 300 grams experiences a force of 200 newtons. Find the energy (or work expended) if the mass moves 15 cm. Also find the power if the move is completed in 10 milliseconds. energy = force x distance (N • m) energy = 200 x .15 = 30J power = energy / second (J/sec=Watts) power = 30J/10-2 sec = 3000W = 3kW

power and energy quiz

a Motorola StarTAC cellular phone uses a small 3.6V lithium ion battery with nominal stored energy of 200 joules. For how long will it power the phone if it draws a 3-mA current when in operation?

quiz solution

200 joules = 200 watt-secs 3.6 V x 3 mA = 1.08 x 10-2 watts 200 watt-secs / 1.08 x 10-2 watts =

18,519 seconds

18,519 seconds / 3600 sec/hr = 5.1 hours

voltmeters and ammeters dc current and voltage measurements are made with (analog or digital type) ammeters and voltmeters voltage measurements are made with red probe (+) at point a, and black probe (-) at point b

a b

+ vab -i

voltmeters and ammeters current measurements require breaking into the circuit so the ammeter is in series with the current flow made with red probe (+) at point b, and black probe (-) at point c

a bc

+ vab -i

ideal meters

ammeters – negligible voltage drop through it

voltmeters – negligible current flows into it

circuit analysis and design

analysis – concerned with the methodological study of a circuit to determine direction and magnitude of one or more circuit variables (V, A) problem statement situation and assumptions goal and requirements plan act verify if correct, solved if not, plan act verify iterate as

needed

WHAT DO YOU KNOW (or, what’s going to be on the test)?

Homework for next week

See website show all work for any credit Dorf & Svoboda, pp. 24-27

Problems 1.3-1, 1.3-2, 1.3-6, 1.3-7, 1.6-3, 1.6-5,

1.6-10, 1.6-12, 1.6-14, 1.6-19 Verification Problem 1-1 Design Problem 1-2