It is the study based on the flow of electrons to design circuits, devices and systems using resisters, capacitors, semiconductors, vacuum tubes etc
It is the energy given by the:
Solar cells etc.
Unit of electricity is kilowatt/hour.
Electrons, electricity, electronics all begin with “ELECTR—” originate from Greek word “ELECTOR” meaning “Beaming Sun” also elector is used for “AMBER” (Arabic: a jewel quality fossilized resin)
CHARGE ON ELECTRON: 1.6 x (10)-19 coulombs.
Where does electricity come from?
To know we need to understand about atoms and their structure
All matters is made up of atoms
Element is a substance that cannot be broken into other substances
Smallest particle of an element is atom
Different elements have different atoms
Atom is like a little solar system
Electron carries negative charge
Proton carries positive charge
Neutron carries no charge
Electrons live in the orbital of the atom
Electrons with highest energy levels exist in the outer most shell.
These are far away from the nucleus.
These are loosely bound to nucleus.
These electrons take part in chemical reaction.
These electrons make bond with other atoms.
It is the energy band due to valance electrons.
ELECTRON ENERGY LEVELS IN AN ATOM
Electrons near to nucleus have less energy
Electrons away from the nucleus have high energy
Each electron have has associated energy
Electrons in the same orbital or shell have small differences in energy levels
Such electrons are grouped in energy bands (see fig below)
CONDUCTION BANDS IN ATOMS
Electrons in VB is loosely bound to atom
Such electrons when gets some energy, it can leave VB and get free from atom
Such electron freely move in the material and not bound to atom
Energy level of such electrons make conduction band (band of energy due to free electrons)
TYPES OF MATERIAL ON BASIS OF ELECTRICAL PROPERTIES
It is the energy difference between valance band and conduction band of an atom.
Energy gap determines the electrical properties
Energy gap determines if material would be (CONDUCTOR, INSULATOR, SEMICONDUCTOR)
Single element materials are best conductors
All these have only one valence electron which is very loosely bound to the atom, and very easily gets free at room temperature
A conductors have a huge num of free electrons
When these electrons move in one direction it make up the current or electronic current
APPLICATIONS OF CURRENT
A medium to carry telecommunication signals
A medium to carry electrical power or energy from one point to another
In insulators, energy gap between valance band and conduction band is very wide
Valance electrons do not jump into the conduction band except under break down conditions where very high voltage are applied across the material
Valance band is completely filled
It do not conduct electricity
It has very high resistance
Energy gap is not wide
With little energy support, electrons can jump from VB to CB
SOME SEMI CONDUTORS
These semi conductors are mostly used in electronics