Chapter 1:

BASIC
ELECTRICAL
DEE 1113 / DMT 1113 / DEI 1003
ELECTRICAL TECHNOLOGY I /
ELECTRICAL TECHNOLOGY

By: Farah Hanan Azimi

BASIC ELECTRICAL
COMPONENTS
Batteries have three parts,
1. A anode (+),
2. a cathode (-),
3. electrolyte
The Nickel Cadmium (NiCd) battery.
The Nickel-Metal Hydride (NiMH) battery.
The Lead Acid battery.
The Lithium Ion battery.
The Lithium Polymer battery.
A resistor is a passive two-terminal electrical
component that increases electrical resistance of a
circuit element.

FUNCTION :
• to reduce the flow of electricity in a circuit.
• to divide voltages
• adjust signal levels
• bias active elements
• terminate transmission lines, among other uses
 Capacitors
 A basic capacitor has two parallel plates
separated by an insulating material
 A capacitor stores an electrical charge
between the two plates
 The unit of capacitance is Farads (F)
 Capacitance values are normally smaller, such
as µF, nF or pF
 Capacitors
Basic capacitor construction
Dielectric
material

Plate 2
The dielectric material is an
insulator therefore no
current flows through the
capacitor

Plate 1
 Capacitors
Capacitors store charge. They
have two metal plates where
charge is stored, separated by
an insulating dielectric.

To charge a capacitor, it must be connected to a voltage supply. When a capacitor

is connected to a battery, a current flows in he circuit until the capacitor is fully
charged, and then stops. An equal but opposite charge builds up on each plate
causing a potential difference across the two plates. No charge can flow between
them because of the insulating dielectric.

Electrons are attracted + Electrons are repelled

from this plate of the from the negative
capacitor to the e- e- terminal of the cell and
positive terminal of the pushed onto this plate
cell. This leaves the
plate ‘electron e- + e-
of the capacitor. The
capacitor plate has an
deficient’ and so it is excess of electrons and
positively charged. so is negatively charged.
Capacitors
Types of capacitors
 The dielectric material
determines the type of
capacitor
 Common types of
capacitors are:
 Mica
 Ceramic
 Plastic film
Capacitors
 Some capacitors are
polarised, they can
only be connected
one way around
 Electrolytic
capacitors are
polarised
Capacitors - Variable capacitors
 Variable capacitors are
used in communication
equipment, radios,
televisions and VCRs
 They can be adjusted by
consumers by tuning
controls
 Trimmers are internal
adjusted capacitors that
a consumer cannot
adjust
Capacitors - Variable capacitors
 These variable
capacitors would be
difficult to squeeze
into your mobile
phone and iPod
 Current technology
uses semi-conductor
variable capacitors
called varactors
(varicaps)
Inductor
1. An inductor is about
as simple as an
electronic component
can get -- it is simply
a coil of wire.

2. It turns out, however,

that a coil of wire can
do some very
interesting things
because of the
magnetic properties
of a coil.
 TRANSFORMER
This is an
electrical device
used to increase
or decrease the
value of
alternating
current (AC ).
Other Electrical components
FUSE JUMPERS
 FUSE

Symbol

• A fuse is a type of low resistance resistor that acts as a

sacrificial device to provide over current protection, of
either the load or source circuit.
• Its essential component is a metal wire or strip that melts
when too much current flows through it, interrupting the
circuit that it connects.

Good Blown
fuse fuse

• Short circuits, overloading, mismatched loads, or device failure are

the prime reasons for excessive current.
• Fuses can be used as alternatives to circuit breakers.
 JUMPERS

Jumpers are small devices that are used to

control the operation of hardware devices
directly, without the use of software.
A jumper is a mechanical switch that is
easily modified by hand.
 CHARGE, CURRENT,
VOLTAGE, ENERGY, POWER
 ELECTRICAL CHARGE (Q)
• Characteristic of subatomic particles that determines their electromagnetic
interactions

• An electron has a -1.602x10-19 Coulomb charge

• The rate of flow of charged particles is called current.

 CURRENT (I)
• Current = (Number of electrons that pass in
one second) ∙ (charge/electron)
 Notice that 1 ampere = 1 Coulomb/second
• The negative sign indicates that the current inside is
actually flowing in the opposite direction of the
electron flow

Electrons

Current
 AC and DC CURRENT

DC Current has a AC Current has a

constant value. value that changes
sinusoidally.
• Notice that AC current
changes in value and direction

• No net charge is transferred

  Direct Current

 Current that is produced in a circuit by a steady

voltage source. Direct current is when electrons
flow in one direction in a circuit only.

In direct current the

Electrons flow voltage will go to
from – to + maximum or PEAK

Volts
(almost) instantly so
on a graph it looks
like this.  0 Time
1 sec

27
  Alternating Current
Current that is produced by a voltage source
that changes polarity, or alternates, with time.
In alternating current the voltage goes to PEAK positively then
reverses to zero, the current then goes to PEAK in the negative.
When the electrons have gone once in each direction makes
cycle and is represented with a sine wave as seen in the graph.

Volts
0

When armature cuts magnet field at peak

Time
When armature runs parallel to field at zero

http://www.walter-fendt.de/ph14e/generator_e.htm Draw this g

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Chapter 2
Current
Current (I) is the amount of charge (Q) that
flows past a point in a unit of time (t).
Q
I
t
One ampere is a number of electrons having a total charge of 1 C
move through a given cross section in 1 s.

What is the current if 2 C passes a point in 5 s? 0.4 A

Principles of Electric Circuits - Floyd © Copyright 2006 Prentice-Hall

Chapter 2
Force
There is a force (F) between charges. Like
charges repel; unlike charges attract.

•The force is directly proportional to charge.

•The force is inversely proportional to square of distance.

_
+ + +

Principles of Electric Circuits - Floyd © Copyright 2006 Prentice-Hall

Chapter
Motion of 2
negatively charged electrons in a copper wire when
placed across battery terminals with a difference in potential of
volts (V).

Principles of Electric Circuits - Floyd © Copyright 2006 Prentice-Hall

Chapter 2

Current (I) is the

amount of charge
(Q) that flows
past a point in a
unit of time (t).

• Flow of electric charges

– -ve charge (electron) flow to +ve terminal.
– + ve charge flow to –ve terminal
– This motion creates electric current
• It is conventional to take the current flow as the movement of positive
charge, that is opposite to the flow of electron.
Principles of Electric Circuits - Floyd © Copyright 2006 Prentice-Hall
Chapter 2 Current

direct current Alternating current

Damped current
exponential current

Principles of Electric Circuits - Floyd © Copyright 2006 Prentice-Hall

 VOLTAGE
• Voltage is a measure of the potential energy that
causes a current to flow through a transducer in a
circuit.
• Voltage is always measured as a difference with
respect to an arbitrary common point called ground.
Chapter 2
Voltage
Every source of voltage is established by simply
creating a separation of +ve and –ve charges

+ -
W
V
Q + -
+ e-
-
Work is done as a charge is
+ -
moved in the electric field
from one potential to another. + -
+ -
Voltage is the work per charge
done against the electric field. + -
+ -
+ -
Principles of Electric Circuits - Floyd © Copyright 2006 Prentice-Hall
Chapter 2
Voltage
Definition of voltage

W
V
Q

One volt is the potential difference (voltage) between

two points when one joule of energy is used to move
one coulomb of charge from one point to the other.

One Coulomb of charge is the total charge associated

with 6.242 x 1018 electrons

Principles of Electric Circuits - Floyd © Copyright 2006 Prentice-Hall

Chapter 2
Voltage

Voltage
Voltage is responsible for establishing current.
Sources of voltage
e-
include batteries, solar +
e-

cells, and generators.

Zinc Copper
Generally can be divided into: Zn2+
(anode)
Zn + 2e
-
(cathode)
Cu 2+ + 2e
- Cu
a) Batteries (chemical
reaction)
b) Generators (electro- ZnSO4
solution
mechanical)
Porous CuSO4
c) Power supplies barrier solution

(rectification)

Principles of Electric Circuits - Floyd © Copyright 2006 Prentice-Hall

Chapter 2
Voltage Sources

Principles of Electric Circuits - Floyd © Copyright 2006 Prentice-Hall

Chapter 2
Voltage Sources

Principles of Electric Circuits - Floyd © Copyright 2006 Prentice-Hall

Chapter 2 Voltage & current
source

Voltage Current

Principles of Electric Circuits - Floyd © Copyright 2006 Prentice-Hall

 A Circuit
Current flows from the higher voltage terminal of the
source into the higher voltage terminal of the
transducer before returning to the source.
I

+ Transducer - The source expends

Voltage energy & the transducer
+
converts it into
something useful
Source
Voltage I

-
 Chapter 2

Basic Circuit
A basic circuit consists of
 a voltage source,
 a transmission system and
 a load
 a control apparatus.
An example of a basic circuit is the flashlight,
which has each of these.
Switch Metal strip

Metal reflector Spring

Principles of Electric Circuits - Floyd © Copyright 2006 Prentice-Hall

Chapter 2 Basic Circuit Elements
• One element on simple circuit is a
mathematical model for electric apparatus
that have two terminals.
Basic Circuit
Elements

Active Elements Passive Elements

Could supplied power to Only could absorb
circuits power
Example : Voltage and Example : resistor,
Current source inductor, capasitor etc.

Principles of Electric Circuits - Floyd © Copyright 2006 Prentice-Hall

Chapter 2 Basic Circuit Elements

Principles of Electric Circuits - Floyd © Copyright 2006 Prentice-Hall

Chapter 2 Basic Circuit Elements

Active Elements/Devices
• Sources expend energy and are considered active
devices

• Their current normally flows out of their highest

voltage terminal

• Sometimes, when there are multiple sources in a

circuit, one overpowers another, forcing the other
to behave in a passive manner

Principles of Electric Circuits - Floyd © Copyright 2006 Prentice-Hall

Chapter 2 Basic Circuit Elements

Passive Elements/Devices
• A passive transducer device functions only when
energized by a source in a circuit
 Passive devices can be modeled by a resistance

• Passive devices always draw current so that the

highest voltage is present on the terminal where the
current enters the passive device
+ V>0 -  Notice that the voltage is
measured across the device
 Current is measured
I>0
through the device

Principles of Electric Circuits - Floyd © Copyright 2006 Prentice-Hall

Chapter 2 Power
• The rate at which energy is transferred from an
active source or used by a passive device
• Power is conserved in a circuit - ∑ P = 0
Power = Current x Voltage
P=IxV
• We associate a positive number for power as power
absorbed or used by a passive device
• A negative power is associated with an active device
delivering power
I If I=1 amp If I= -1 amp If I= -1 amp
+ V=5 volts V=5 volts V= -5 volts
V Then passive Then active Then passive
- P=+5 watts P= -5 watts P=+5 watts
(absorbed) (delivered) (absorbed)

Principles of Electric Circuits - Floyd © Copyright 2006 Prentice-Hall

Chapter 2
Example
• A battery is 11 volts and as it is charged, it
increases to 12 volts, by a current that starts
at 2 amps and slowly drops to 0 amps in 10
hours (36000 seconds)

• The power is found by multiplying the current

and voltage together at each instant in time

• In this case, the battery (a source) is acting

like a passive device (absorbing energy)

Principles of Electric Circuits - Floyd © Copyright 2006 Prentice-Hall

Voltage, Current & Power
COMMON ELECTRONIC SYMBOL & UNITS

Quantity Symbol Unit

Current I Ampere (A)

Voltage V Volt (V)

Resistance R Ohm ()

Frequency f Hertz (Hz)

Capacitance C Farad (F)

Inductance L Henry (H)

Power P Watt (W)

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 A DIGITAL BASIC ELECTRICAL
MULTIMETER (DMM) is a
test tool used to measure two or
more electrical values—principally
INSTRUMENTS
voltage (volts), current (amps) and An OSCILLOSCOPE is a laboratory instrument
resistance (ohms).
commonly used to display and analyze the waveform of
electronic signals. In effect, the device draws a graph of the
instantaneous signal voltage as a function of time.

DC POWER SUPPLIES are power

supplies which produce an output DC A FUNCTION GENERATOR is a specific
voltage. form of signal generator that is able to generate
waveforms with common shapes (AC Signal)
SCIENTIFIC & ENGINEERING NOTATION
METRIC PREFIX
Scientific & Engineering Notation
We will learn about:
• How to express numbers in scientific notation.
• How to express numbers in engineering notation.
• How to express numbers in SI prefix notation.

53
 Scientific Notation
• Scientific notation is a way of writing very large
and very small numbers in a compact form.
• A number written in scientific notation is
written in the form:
a × 10b
Where: a is a number greater than 1 and less than 9.99
b is an integer
Examples:
3.24 × 105
1.435 × 10-7
3.29× 106
7.3 × 10−2
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Writing A Number in Scientific Notation
• Shift the decimal point so that there is one digit
(which cannot be zero) before the decimal point.
• Multiply by a power of 10, equal to the number of
places the decimal point has been moved.
• The power of 10 is positive if the decimal point
is moved to the left and negative if the decimal
point is moved to the right.

55
Scientific Notation: Example #1
Example:
Express 5630 in scientific notation.

56
 Scientific Notation: Example #1
Example:
Express 5630 in scientific notation.

Solution:
5630 = 5630.0 = 5.630 × 103

3 Moves

Note: Because the decimal point was moved to the left, the power of 10 is positive.

57
Scientific Notation: Example #2
Example:
Express 0.000628 in scientific notation.

58
 Scientific Notation: Example #2
Example:
Express 0.000628 in Scientific Notation.

Solution:
0.000628 = 6.28 × 10-4

4 Moves

Note: Because the decimal point was moved to the right, the power of 10 is negative.

59
 Engineering Notation
• Engineering notation is similar to scientific
notation. In engineering notation the powers
of ten are always multiples of 3.
• A number written in engineering notation is
written in the form:
a × 10b
Where: a is a number greater than 1 and less than 999
b is an integer multiple of three
Examples:
71.24 × 103
4.32 × 10-6
320.49× 109
60
123.452 × 10−12
Writing A Number in Engineering Notation
• Shift the decimal point in “groups of three” until
the number before the decimal point is between
0 and 999.
• Multiply by a power of 10 that is equal to the
number of places the decimal point has been
moved.
• The power of 10 is positive if the decimal point
is moved to the left and negative if the decimal
point is moved to the right.
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Engineering Notation: Example #1
Example:
Express 16346000000 in engineering notation.

62
Engineering Notation: Example #1
Example:
Express 16346000000 in engineering notation.

Solution:
16346000000 = 16346000000.0 = 16.346 × 109

9 Moves

Note : Because the decimal point was moved to the left, the power of 10 is positive.

63
Engineering Notation: Example #2
Example:
Express 0.0003486 in engineering notation.

64
Engineering Notation: Example #2
Example:
Express 0.0003486 in engineering notation.

Solution:
0.0003486 = 0.0003486 = 348.6 × 10-6

6 Moves

Note : Because the decimal point was moved to the right, the power of 10 is negative.

65
 SI Prefixes
• SI prefixes are a shorthand way of writing
engineering notation for SI numbers.

• The International System of Units

(abbreviated SI from the French Système
International d'Unités) is the modern form of the
metric system. It is the world's most widely used
system of units for science and engineering.

66
Commonly Used SI Prefixes
Value Prefix Symbol

1012 tera T

109 giga G

106 mega M

103 kilo k

10-3 milli m

10-6 micro 

10-9 nano n

10-12 pico p

10-15 femto f 67
 SI Notation: Example #1
Example:
Express 27500  using standard SI notation.
(Note:  is the Greek letter omega. In electronics, it is the symbol used for resistance.)

68
 SI Notation: Example #1
Example:
Express 27500  using standard SI notation.
(Note:  is the Greek letter omega. In electronics, it is the symbol used for resistance.)

Solution:
27500  = 27.5 × 103  = 27.5 k 

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 SI Notation: Example #2
Example:
Express 0.000568 Volts using standard SI notation.

70
 SI Notation: Example #2
Example:
Express 0.000568 Volts using standard SI notation.

Solution:
0.000568 Volts = 0.568 × 10-3 Volts = 0.568 mVolts
0.000568 Volts = 568.0 × 10-6 Volts = 568.0 Volts

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