BASICS OF ELECTRICAL AND ELECTRONICS ENGINEERING LECTURE SLIDES.pptx

FUNDAMENTALS
OF
ELECTRICAL
AND
ELECTRONIC
ENGINEERING

OUTLINE ( LECTURES 1&2)
LECTURE 1
INTRODUCTION
TO EEE
BASIC CONCEPTS
AND DEFINITIONS
LECTURE 2

OBJECTIVES OF THE COURSE
 Students should
understand basic concept in
Electrical Engineering:
Charges, Current, Resistor,
Voltage, Power, Energy.
1
 Students should also
understand the principles of
ohms law
2
 Students should be
exposed to the practical
applications of those laws
3

OVERVIEW OF ELECTRICAL/ELECTRONICS ENGINEERING

BASIC CONCEPTS AND DEFINATIONS
INTRODUCTION
Given an electrical network, the network analysis involves various methods. The process of finding the
network variables namely the voltage and currents in various parts of the circuit is known as network
analysis. Before we carry out actual analysis it is very much essential to thoroughly understand the
various terms associated with the network. In this chapter we shall begin with the definition and
understanding in detail some of the commonly used terms.

HIGHLIGHTS OF ELECTRIC POWER DEVELOPMENTS
Ampère began by repeating Oersted's work, and before the end of September 1820, had made a
discovery of his own:
1827 Alessandra Volta devised the first electric battery.
The Resistance was discovered by the year 1827 from Georg Simon Ohm, a German electrician.
1830 Sir Humphrey Davy discovered electromagnetism and the arc light.
1831 Michael Faraday demonstrated the process of magnetic induction.
1880 Thomas A. Edison invented a practical incandescent bulb and discovered that lamps could be
connected in parallel, permitting one or more to be turned off without disconnecting the whole system.
1882 Edison’s Pearl Street electric generating station was placed in operation in New York City.
1888 Nikola Tesla secured patents for an induction motor and for a new Poly phase alternating current
system.
1888 After organizing the Westinghouse Electric Company in 1886, George Westinghouse was granted a
contract to provide generators for the Niagara hydroelectric project, the first such project in history.

CHARGE
The most basic quantity in an electric circuit is the electric charge. We all experience the effect of electric
charge when we try to remove our wool sweater and have it stick to our body or walk across a carpet and
receive a shock.
Charge is an electrical property of the atomic particles of which matter consists, measured in coulombs
(C). Charge, positive or negative, is denoted by the letter q or Q.
We know from elementary physics that all matter is made of fundamental building blocks known as
atoms and that each atom consists of electrons, protons, and neutrons. We also know that the charge
‘e’ on an electron is negative and equal in magnitude to 1.602x10-19 C, while a proton carries a positive
charge of the same magnitude as the electron and the neutron has no charge. The presence of equal
numbers of protons and electrons leaves an atom neutrally charged.

PRACTICAL APPLICATION OF CURRENT & CHARGES

PRACTICAL APPLICATION OF CURRENT & CHARGES
EXAMPLE 1:
Determine the current in a circuit if a charge of 80 coulombs passes a given point in 20 seconds (s).
EXAMPLE 2:
Determine the total charge entering a terminal between t=1 s and t=2 s if the current passing the
terminal is Ii = (3t ^2 − t ) A.

VOLTAGE OR POTENTIAL DIFFERENCE

VOLTAGE OR POTENTIAL DIFFERENCE: MATHEMATICALLY

VOLTAGE OR POTENTIAL DIFFERENCE: MATHEMATICALLY
EXAMPLE 1

VOLTAGE OR POTENTIAL DIFFERENCE: PRACTICAL SUMMARY

RESISTOR AND RESISTANCE
Resistors are used in virtually all electronic circuits and many electrical ones. Resistors, as their name
indicates resist the flow of electricity, and this function is key to the operation most circuits.
There are two main circuit symbols used for resistors. The oldest one is still widely used in North America
and consists of a jagged line representing the wire used in a resistor.
The other resistor circuit symbol is a small rectangle, and this is often termed the international resistor
symbol and it is more widely used in Europe and Asia.

The first major categories into which the different types of resistor can be fitted is into whether they are
fixed or variable. These different resistor types are used for different applications:
Fixed resistors: Fixed resistors are by far the most widely used type of resistor. They are used in
electronics circuits to set the right conditions in a circuit. Their values are determined during the design
phase of the circuit, and they should never need to be changed to "adjust" the circuit. There are many
different types of resistor which can be used in different circumstances and these different types of
resistor are described in further detail below.

Variable resistors: These resistors consist of a fixed resistor element and a slider which taps onto the
main resistor element. This gives three connections to the component: two connected to the fixed
element, and the third is the slider. In this way the component acts as a variable potential divider if all
three connections are used. It is possible to connect to the slider and one end to provide a resistor with
variable resistance.

Other types of resistor
Whilst the majority of resistors are standard fixed resistors or variable
resistors, there is a number of other resistor types that are used in some
more niche or specialized applications.
Light dependent resistor / photo-resistor: Light dependent resistors or
photo-resistors change their resistance with the level of light. They are
used in a number of sensor applications and provide a very cost effective
solution in many instances
Varistor: Varistors are available in a number of forms. Essentially these
electronic components vary their resistance with the applied voltage and
as a result they find uses for spike and surge protection. Often they may
be seen described as Movistors, which is a contraction of the
words Metal Oxide Varistor.

In Current and Resistance we described the term ‘resistance and explained the basic design of a resistor. Basically,
a resistor limits the flow of charge in a circuit and is an ohmic device where V=IR, R=V/I. Most circuits have more
than one resistor. If several resistors are connected together and connected to a battery, the current supplied by the
battery depends on the equivalent resistance of the circuit.
The equivalent resistance of a combination of resistors depends on both their individual values and how they are
connected. The simplest combinations of resistors are series and parallel connections. In a series circuit the output
current of the first resistor flows into the input of the second resistor; therefore, the current is the same in each
resistor. In a parallel circuit all of the resistor leads on one side of the resistors are connected together and all the
leads on the other side are connected together. In the case of a parallel configuration, each resistor has the
same potential drop across it, and the currents through each resistor may be different, depending on the resistor.
The sum of the individual currents equals the current that flows into the parallel connections.
.
FORMULAS

.
FORMULAS
Rtotal = R1 + R2 + R3 +……+Rn

.
PRACTICAL INFERENCE OF RESISTORS AND RESISTANCE

.
PRACTICAL INFERENCE OF RESISTORS AND RESISTANCE
Applications of Resistor
Following are the applications of resistors:
Wire wound resistors find applications where balanced current control, high sensitivity,
and accurate measurement are required like in shunt with ampere meter.
Photo-resistors find application in flame detectors, burglar alarms, in photographic
devices, etc.
Resistors are used for controlling temperature and voltmeter.
Resistors are used in digital multi-meter, amplifiers, telecommunication, and
oscillators.
They are also used in modulators, demodulators, and transmitters.

SUMMARY OF FORMULAS
POINTS TO NOTE
.
SUMMARY ON CHARGE ( Q )
MEASURED IN COULOMB ( C )
6.3 X 10^18 = 1Coulomb
Therefore we can say
1 electron = 1.602 x 10^-19C
Q at arbitrary level
Q = It ; Where I = current(A) and t = time (s)
Q at different time
SUMMARY ON CURRENT ( I )
MEASURED IN AMPERE ( A )
“ CURRENT” when Calculating Charge per Time
I = Q/t ; where Q = Charge and t = time
CURRENT when being defined as the rate of charge passing
through a point:
i = dq/dt ; where dq and dt = derivative of charge and time
respectively ( thus change in charge with respect to charge in
time from one point to another)
CURRENT in OHMS LAW APPLICATION
i = V/R ; where V = voltage and R = Resistance

SUMMARY OF FORMULAS
POINTS TO NOTE
.
SUMMARY ON RESISTANCE ( Q )
MEASURED IN OHM ( Ω)
RESISTANCE IN PRACTICAL MATERIALS
R = ΡL/A ; where Ρ= resistivity coefficient , L
= length of the material and A = Cross Sectional
area
RESISTANCE in OHMS LAW APPLICATION
R = V/I ; where V= voltage and I = current
SUMMARY ON VOLTAGE OR P.D ( V )
MEASURED IN VOLTS ( V )
VOLTAGE when calculating energy consumed in the circuit per
time:
V = dw/dt ; dw = change in energy with respect to dt =
change in time
VOLTAGE drop at any point
V = dw/dq ; dw = change in energy, dq = change in charge
CURRENT in OHMS LAW APPLICATION
V= IXR ; where I= Current and R = Resistance

SUMMARY OF FORMULAS
POINTS TO NOTE
.
SUMMARY ON POWER ( P )
MEASURED IN WATTS ( W)
POWER in energy consumption devices
P = w/t ; where w=energy and t = time
ALSO
P = dw/dt
POWER in OHMS LAW APPLICATION
P= VXI
; P=Ri^2; P=V^2/R ; where V= voltage
and I = current and R = resistance
SUMMARY ON ENERGY ( w )
MEASURED IN JOULES ( J)
ENERGY absorb or supplied from a time to another;
wwwwww
Where P = POWER and V = VOLTAGE, i = CURRENT
ENERGY in OHMS LAW APPLICATION
w = POWER X TIME
w = P X t

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