Electrical Principles 1 - WSIEE

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Electrical Principles 1 - WSIEE
Electrical Principles 1
- 7793A, Applied
Electricity 1 - 7793AV
Mt Druitt College of TAFE
Dept. Electrical Engineering
Assessment
Theory Test 1: 25%
 Theory Test 2: 50%
 Practical: 25%

 May
consist of 2 separate tests
© Mike Stacey 2008
2
How to pass the subject – your
responsibility
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Access the web site at
http://wsiee.wikispaces.com/ every couple of
days for:
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Weekly notes – powerpoint slides in *.ppt and *.pdf format:
Print the pdf versions and bring to class BEFORE each
class.
Other material such as revision questions for tests and
related material
It can all be found on a page dedicated to each week of the
subject. You should print this page also.
Store all hard copies in a folder and stay organised!
© Mike Stacey 2008
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Web site – home page
© Mike Stacey 2008
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Web site – class notes index
© Mike Stacey 2008
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Web site – Compulsory Core index
© Mike Stacey 2008
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What you require
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The workbook: Student Workbook available from the
college bookstore: "Electrical Principles for Advanced
Diploma Courses, Workbook 1"
Text: (Recommended) Phillips, Peter 1996, Electrical
Principles 1 ISBN 0 170092127 Thomas Nelsen,
Melbourne, Victoria.
Weekly notes downloaded and printed from the website
A Calculator: Capable of performing rectangular -> polar
conversions, logs, trig, base N number systems.
Folder to store weekly material and pens and paper
© Mike Stacey 2008
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Topics
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Basic Electrical Concepts
Ohm's Law
Power
Series Circuits
Parallel Circuits
Series - Parallel Circuits
Voltage Sources
Effects of a Current
Electrical Measurement
Resistance
Practical Resistors
Sources of electrical energy
© Mike Stacey 2008
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Today’s Topics
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See workbook pages 2.1 - 2.6
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The Atom
Potential difference, current, resistance
Source of electricity
Circuit diagrams
Current direction
Current effects
SAFETY
Maths review
Homework: Complete Tutorial 1 (P 2.8) and Safety Tutorial
(P2.7) for next week
© Mike Stacey 2008
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The Planetory Atom (ref P2.1)
Figure 1
An atom consists of a central nucleus surrounded by orbiting electrons.
Electrons are negatively charged and protons positively charged,
© Mike Stacey 2008
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Potential Difference, Current and
Resistance (ref P2.1)
Figure 2
Resistance is
the ability of a
material to
oppose the flow
of electrons.
A potential difference exists between negatively charged and positively
charged bodies.
© Mike Stacey 2008
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Water Analogy for Current Flow [1]
Figure 3
A water-pressure difference causes a current of water to flow between
the two tanks. The thick pipe passes a larger current than the thin
pipe.
© Mike Stacey 2008
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Water Analogy for Current Flow [2]
Figure 3
© Mike Stacey 2008
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Basic Sources of Electricity (ref P2.2)
Zinc-carbon voltage cell
Chemical action removes
electrons from the carbon.
Carbon rod is then positively
charged. Electrons
accumulate in the zinc
hence it is negatively
charged.
There is a potential
difference, or voltage,
between the +ve and –ve
terminals.
Figure 4
© Mike Stacey 2008
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Basic Electric Circuit (ref P2.2)
Switch open: no
conduction path between
battery terminals. No
current flow.
Figure 5
Switch closed: potential
difference between
battery terminals causes
a current to flow from
negative terminal,
through the lamp and
switch, to the positive
battery terminal.
Result: the lamp lights
up.
© Mike Stacey 2008
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Circuit Diagrams (ref P2.2)
Figure 6
© Mike Stacey 2008
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Current Direction (ref P2.3) &
Effects of Electric Current
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Current Flow
 Conventional
Current direction: Positive to Negative
 Direction of Electron Flow: Negative to Positive
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Effect of electric current
 Heat
 Magnetic
field
 Chemical effects
 Muscle contraction
© Mike Stacey 2008
17
Conditions Required for Current Flow
(ref P2.3)
Source of EMF
 Conducting path
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© Mike Stacey 2008
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