Transcript ELEC130 Electrical Engineering 1

ELEC130
Electrical Engineering 1
Gunilla Burrowes
EA G24
(p) 4921 6352
email gunilla@ee
Mon &Fri 2-3pm
Fernando Martinez
EE 102
4921 6149
fmm@ecemail
Help Desk
HELP - EA G08 - during office hours
Material
 5 modules
1 - Introductory Circuit Techniques
2 - DC Circuit Tools
3 - AC Circuit Tools
4 - Applications in Power
5 - Applications in Communications &
Instrumentation
Week 1 & 2
Week 2 3 & 4
Week 5 & 6
Week 7 & 8
Week 9 10 11
Week 12 & 13
 Electronic Workbench: Faculty PC’s Rm. ES210 - Go to Diomedes
 Login: cstudentnumber Password: access keys on students card +
daymonth (ddmm) of birth
 TopClass: http://www.newcastle.edu.au:86/topclass/
 Username: first name.last name
 Password: date of birth ddmmyy
 Email: first name.last name@studentmail
Lectures
 2 hour / week for 13 weeks - Monday 5 -7pm
 Quizzes - Weeks 3 6 8 11 13
 Course Information Booklet
 Student Responsibility
 Survey
Student Responsibility
 Expect CIVIL Behavior
 Work consistently
 Progressive assessment
 Teaching / Learning
 Rote Learning
 Where to go for help
 Material may not always seem relevant
Its Up To You
The onus is shifted to you to “learn”
(independently)
Majority of learning will take place when you
tackle the subject material
BURY NOW the natural tendency to assume a
passive role (waiting to be taught)
Text & References
 Course information Booklet & Safety Notes
$12.00 Purchase after this lecture - Foyer EA
 Several Alternative Texts
Floyd - Principles of Electric Circuits
Dorf - Introduction to Electric Circuits
Hambley - Electrical Engineering
Johnson - Electric Circuit Analysis
 Student Problem Sets - Library
 Text references
 Study Guide
Tutorials
1 hours / week. Start next week
 Check your group on Noticeboard Foyer EA
You must Enroll Tonight
ASK QUESTIONS
 Electronic Workbench - ES 210
Introduction - Tutorial 2 Week 3
Matrix - textbook
 Tutorial 1
Laboratory
 2 hours / week - start next week
 Voluntary Laboratory THIS WEEK
 Check your group on Noticeboard Foyer EA
You Must Enroll Tonight - Foyer EA
 EE 103(a)
 9 laboratory exercises (Lab 1 goes for 2 weeks)
 2 practical tests - 15 % each (Total 30%)
 All experiments are considered “examinable”
 Keep a Laboratory diary
Laboratory
 Attendance Sheets
 Safety - notes will be attached to course information
booklet- READ THEM
 Use Common Sense
 Keep the Laboratory Tidy
 BE PREPARED
Help Desk - EE 102 / EE 103
Monday
9 - 11 am
Wednesday
8 - 9 am
1 - 2 pm
8 - 9 pm
Assessment
Final grade for ELEC 130 will be
5 quizzes @ 4% each
2 laboratory tests @ 15%
June Exam @ 50%
20%
30%
50%
Engineering
 Concerned with creation of solutions to problems, based
on science and technology
 Systems Engineering
emphasises a wholistic design methodology
 encompasses the whole life cycle of the product
 Role taken on by engineering in technology-based
enterprises
 creative element to convert a need into a service or product
 integration of all processes into a single coherent process
Multi-disciplinary & Integrating
Nature
Economics
Manufacturing
Social
Reliability
Legal
Maintainability
Environmental
Human Engineering
Engineering as a Process
Market
Market
research
Engineering
Technology, R & D
Marketing,
sales and
support
Changing Nature of Engineering
The essence of engineering is a product of the
human mind
For the mind to be creative, it must operate on
concepts (not just facts)
Swing back to the wholistic view
complexity of the interaction with society
rapid and fascinating development of engineering
science
Engineering
Involves two complementary subjects
the body of knowledge known as engineering
science
the process of applying that knowledge
Aims of ELEC 130
To study the concepts of basic electrical
elements & circuits
Start with laws of physics to derive simple ‘rules’
for electrical circuits
Same rules apply to
‘light’ current i.e. computers, communication
‘heavy’ current i.e. power grid, motors
Overview of DC Circuits
Units & Notation
What is a circuit?
What is Charge / Current?
What is Voltage?
Voltage & Current sources
Power
Resistance
Ohm’s Law
Units
SI system - kg,m,s
Others derived from these - Volts, Farads
Scaling of Units
p
n

m
_
K
M
G
pico
nano
micro
milli
unit
kilo
mega
giga
10-12
10-9
10-6
10-3
1
103
106
109
Notation
Time varying quantities - lower case
e.g. v(t), i(t)
sometimes assume time - v(t) = v
Time invariant quantities - upper case
e.g. V, R,
Remember to include units of measure
e.g. 15 Volts
What is a circuit?
In ELEC130 we assume that a circuit comprises
of two or more elements connected by electrical
conductors.
Electrical conductors allow electricity to flow
(unimpeded) between elements
Electricity must flow in a CLOSED path or circuit
Open Circuit
 A ‘Break’ in a circuit is
called an open circuit
Short Circuit
 A ‘bypass’ of an element
is called a short circuit
Different Geography
 Two circuits may have
the same topology but
different geography
Charge
Charge is the phenomenon giving rise to those
forces observed between electrical charged
bodies. There are 2 kinds of charges: pos & neg
Symbol Q (constant) or q(t) (time varying)
Defined in terms of the charge on 1 electron
~=1.6x10-19 Coulombs
or stated as Charge on 6.2x1018 electrons is 1
Coulomb
Current
 Motion of charge constitutes an electric current
 Conventional current is the flow of positive charges
 Electron current is negative charges
 Measure of rate of flow of charge
1 Ampere = 1 Coulomb/sec
 or Charge is the sum or ‘accumulation’ of current
Symbol I
i(t)
Current cont..
The primary purpose of electric circuits is to
move or transfer charges along specific paths
circuit
circuit
3A
=
-3A
Voltage
 Fix one Coulomb of charge in space … energy input
(work) is required to bring another Coulomb of charge
from a point A to a new point B closer to the fixed
charge ……. the potential energy difference between
points B & A is known as voltage:
1 Volt = 1 Joule / Coulomb
 Charge tends to flow from a higher voltage (potential) to
a lower voltage - resulting charge flow is current
Symbol V
v(t)
Power
 Power is  energy /  time
 P = VI Watts
 p = v(t).i(t) W
 i.e. need voltage and current (at the same time) to do
work
 Power can be +ve and -ve; it can be ‘absorbed’ or
delivered
 Symbol: P p(t)
Units: Watts
W
Power Convention
If v(t)  0 and
i(t) 0 then p  0
i(t)
Power is said to be
absorbed by the
circuit
 NB polarity of voltage
and direction of current
+
v(t)
-
Circuit
or
element
Voltage & Current Source
An ideal voltage source maintains its stated
voltage regardless of the load attached
Independent voltage source
An ideal current source supplies its stated
current regardless of the load attached
independent current source
VA
VA
VA
IB
IB
Ohm’s Law
Some materials are good conductors of
electricity, some are poor
In a ‘good’ conductor, the current flowing
through the conductor is (approx.) proportional
to the voltage across it.
Constant of proportionality is known as
resistance, given symbol is R
Ohm’s Law:
v(t) = R i(t)
Example
i(t)
4V
10