BASIC ELECTRONICS

&
ELECTRICAL
TECHNOLOGY
1.0 INTRODUCTION TO
ELECTRONICS
 1.1 Introduction and scope of Electronics:
Electronics is the branch of science and Technology
that deals with the study of flow and control of electrons
(electricity) in vacuums, gases, and semiconductors.
There are probably many different pieces of
technology inside of your house, workplace, industries,
defence etc.
Electronics makes possible such modern wonders as
television, radio, stereo system, Radar, X-ray, tape recorders
and high-speed computers.
Scope of Electronics
ELECTRONICS
 ELECTRONICS

COMMUNICATIO
N& DEFENCE INDUSTRY MEDICAL INSTRUMENTATION
ENTERTAINMENT SCIENCE

X-ray
AUDIO & Radar
LINE WIRELESS Guided missiles ECG
VEDIO Electron Microscope
COM COM Coded
SYSTEMS
communication
Precision Measuring Instruments
Telegraph Radio Stereo players Automatic control sys
EG: CRO,Signal Generator
TV Tape recorders Computers
Multimeter
Heating and welding s/m
Telephone Satellite
Teleprinters
 1.2 INTRODUCTION TO ELECTRONICS
What is Electronics?
The word “electronics” is derived from
ELECTRON machanICS which means the study of
an electron behavior under different conditions of
externally applied fields.
Electronics can be divided in 3 major fields:
1.Computers-Processing,storage and retrieval of data.
2.Communication-Transfer of information such as voice,
pictures, data etc
3.Control-Circuits used to control electronic motors, light etc.
 Introduction
• In this world every material is a MATTER(Anything that
occupies space and has weight)
• All materials are made up of molecules and molecules are
made up of atoms.
• A molecule is the smallest part of matter which can exist by
itself and contains one or more atoms.
• From this, we can conclude that matter may be found in
any one of the three states: SOLIDS, LIQUIDS, and GASES.
Elements and compounds:
• An element is a material that is made of only one type of atom .
E.g: Copper, Oxyegen, Silicon
•A compound is a material that is made up of molecules that contain more than

one type of atom.

E.g: H20
Basic Structure of Atom
What are the 3 major parts of an
atom?
What are the 3 major parts of an
atom?

• Proton
• Neutron
• Electron
What are the 3 major parts of an
atom?

• Proton
• Neutron
• Electron
 Nucleus
• The nucleus is the central part of an atom.
It is composed of protons and neutrons.
• The nucleus contains most of an atom's mass.
 Proton
• Protons are positively (+)charged.
• Protons are about 1840 times heavier than the
mass of electrons.
• Each PROTON has a MASS of 1.673x10-27kg.
• In an atom:
No of the protons = No of the electrons
• If 20 protons are present in an atom then 20
electrons will be there to balance the overall
charge of an atom—hence atoms will be neutral
 Neutron
• Neutrons are uncharged particles found in the
atomic nucleus.
• Mass of the Neutrons are approximately same
as that of protons.
 Electron
• Electrons are negatively (-) charged.
• Electrons are the smallest and lightest.
• Electrons surrounds the atom's nucleus.
• Each electron has a MASS of 9.11x10-31kg.
• Electrons determine properties of the atom.
• Electrons (- charge) are attracted to protons (+
charge), this holds the atom together.
•The electrons can arrange themselves in different orbits

according to the formula

N=2n2
N=No of electrons
n=Number of orbits
•Electrons move with constant speed in fixed orbits
around the nucleus
•Each electron has a specific amount of energy
The Atom
 The Atom Hydrogen

Proton Electron

Hydrogen has one proton, one electron and NO neutrons

 The Atom Helium

Proton Electron

Neutron

Helium has two electrons, two protons and two neutrons

 The Atom Boron

Protons Electrons

Neutrons

Boron has five electrons, five protons and six neutrons.

 The Atom Nitrogen

Protons Electrons

Neutrons

Nitrogen has seven electrons, seven protons and seven neutrons.

 The Atom Oxygen

Protons Electrons

Neutrons

Oxygen has eight electrons, eight protons and eight neutrons.

 Mass and atomic number
Particle Relative Mass Relative Charge
Proton 1 1
Neutron 1 0
Electron 0 -1

MASS NUMBER = number of

protons + number of neutrons

SYMBOL

PROTON No./Atomic No. =

number of protons
1. The Atomic Number of an atom = number of
protons in the nucleus.

2. The Atomic Mass of an atom = number of

Protons + Neutrons in the nucleus.

3. The number of Protons = Number of Electrons.

4. Electrons orbit the nucleus in shells.

5. Each shell can only carry a set number of

electrons.`12
What is the Electron Cloud Model?
 What is the Electron Cloud Model?
• Electron cloud: visual model of the most likely
locations for electrons in an atom.
• The electrons moving around the nucleus in a region
called an electron cloud.
• The electron cloud is a cloud of varying density
surrounding the nucleus.
1.3 Conductors, Semiconductors
and Insulators
 1.3 Conductors, Semiconductors and Insulators
Conductors:
• Materials which easily allow the flow of electric current are called
CONDUCTORS.
• Conductors do not hold tightly to the electrons in their VALENCE RING,
and are said to have a large number of FREE ELECTRONS
• Very little electric force is required to make electron flow in conductors.
• This is due to electrons called "FREE ELECTRONS", which exist in the
atoms of conductors.
• "Free electrons" are electrons that are very weakly bonded to the atom. With

very little force, they can be traded to other atoms, or flow to create
electricity.
• Best element conductors include:
• Alloys are also good conductors: Brass & steel
•The atomic structure of good conductors usually includes only one
electron in their outer shell.

It is called a valence electron.

It is easily striped from the atom, producing current flow.

Insulators:
• Materials do not allow electrical current to flow easily,
and these are called INSULATORS
• INSULATORS tend to hold tightly to the electrons in their
VALENCE RING, and do not want to share with other
atoms
• Insulators are quite selfish about sharing their electrons.
• Insulators have a high resistance so current does not flow
in them.
• Insulators have no free electrons
• Good insulators include:
– Glass, ceramic, plastics, & wood
• Most insulators are compounds of several elements.
•The atoms are tightly bound to one another so
electrons are difficult to strip away for current flow.

•The flow of electrons in an insulator is relatively

uncommon, and when it does occur it tends to be
accompanied by intense heat, loud noise, melting or
explosions, smoke and/or flame.
 Semiconductors

• Semiconductors are materials that essentially can be

conditioned to act as good conductors, or good insulators,
or any thing in between.

• Common elements such as carbon, silicon, and germanium

are semiconductors.

• Silicon is the best and most widely used semiconductor.

• Semi-conductors can conduct electricity at a certain
level without being damaged; however, semi-
conductors can be damaged with too much electric
force.

• Semiconductors are materials that have resistivity

values in between those of conductors and
insulators, they are neither good conductors nor
good insulators.
Semiconductor Valence Orbit

• The main characteristic

of a semiconductor
element is that it has
four electrons in its
outer or valence orbit.
• This makes it a
semiconductor.
 Energy Band
• The concept of energy bands is particularly important in classifying materials
as conductors, semiconductors, and insulators.

• An electron can exist in either of two energy bands, the conduction band or
the valence band.

• The width of the forbidden band between the conduction and valence bands
determines whether a material is an insulator, semiconductor, or conductor.

•An electron in an atom can move from one energy level to another when an
atom gains or loses energy
 The energy level Diagram:

• Less negative energies are at the top whereas more negative ones are at
the bottom. It means that it is easier to remove electrons from higher orbits
than lower ones.
• Various energy levels are separated by forbidden energy gaps where an
electron cannot exist.
1.4 Energy band Diagram for 3 type of material
INSULATOR:
• The energy diagram for the insulator shows the
insulator with a very wide energy gap.
• The wider this gap, the greater the amount of
energy required to move the electron from the
valence band to the conduction band.
• Therefore, an insulator requires a large amount of
energy to obtain a small amount of current.
• The insulator "insulates" because of the wide
forbidden band or energy gap.
SEMICONDUCTOR:

•The semiconductor, has a smaller forbidden

band and requires less energy to move an
electron from the valence band to the conduction
band.

•Therefore, for a certain amount of applied

voltage, more current will flow in the
semiconductor than in the insulator.
 1. CONDUCTOR:
• The last energy level diagram in figure is that of a
conductor.
• There is no forbidden band or energy gap and the
valence and conduction bands overlap.
• With no energy gap, it takes a small amount of
energy to move electrons into the conduction band
conductors pass electrons very easily.