Electronics
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Introduction:
The word 'electronics' is derived from 'electron' which is present in every material. The behaviour of an electron under condition of externally
Applied fields is studied under electron mechanics.
Electronics is the branch of science and engineering which deals with the flow of electron through vacuum, gas or semiconductor.
Application of electronics
The electronics plays major role in all sphere of our daily. Some of the major fields of application are of electronics are given below:
1. Communication and entertainment:
Electronics engineering provides different forms of communication such as telegraphy, telephony, tele FAX and data communication utilizes
a pair of wires. With the development of wireless transition it is now possible to transmit any message from one place to another, thousands of km away.
2. Industrial application:
Electronics find important application in automatic circuits in various industries. These are used to control quantity, quality, and thickness of job, cutting, and moisture of content in an item, lightning system, sound system and many more.
CAD (computer aided design) a is also use to create model or diagrams of circuit machine by a computer.
3. Defence application:
The communication system plays an important role during the 2nd world war.
RADAR was the most important development that took place during the Second World War.
With the help of RADAR the exact location of enemy’s aircraft can be determined.
RADAR makes possible for accurately controlling anti-aircraft guns thereby destroying enemy aircraft.
4. Instrumentation:
Electronics instruments like VTVM, cathode ray oscilloscope, frequency counter, signal generator, PH meter, strain gauges etc. Provides an accurate and precise measurement of different parameters than the ordinary instruments.
5. Digital Electronics
In all digital circuitry such as flip- flops, converters, calculators and computer, electronics circuit are being
used. The link between any two computers via a network is an electronics link. Any computer can be connected
to internet through modem which is an electronics devices. Now A Day we use electronic link to transmit and
receive E-mail and FAX messages.
Classification of solids
Solids are classified into conductors, insulators and semiconductors
based on their energy band or energy gap between conduction and valence bands.
Conductors:
Energy band structure of conductor are of two types.
1.The conduction band and valence band are separated by a very small gap. The conduction band is
partially filled with electrons at zero kelvin. By application of a very small field, the conductor starts conducting.
2.In the second type,the valence band and the conduction band overlap. Hence there is no forbidden energy gap. Thus
the resistance of these conductors is very low. The electrical conduction takes place even when a very small electric field is applied.
Insulators:
In insulators, the valence band and the conduction band are separated by a large energy gap(Eg). The
valence band is completely filled and the conduction band is completely empty. Since there are no free electrons,
electrical conduction does not take place. Due to large energy gap, electron are unable to jump to the conduction band even if
electrical field is applied.Therefore electrical conduction is impossible in insulators.
Semiconductors:
In semiconductors,the valence band and the conduction band are separated by a small forbidden gap.At absolute zero,the valence band
is filled the conduction band is empty and no electron are available for conduction.Hence at zero degree kelvin,
semiconductors behave like a perfect insulator. At room temperature, some of the electron gain thermal energy and
jump to the conduction band.They are free to move in the crystal and the available for conduction.
Eg of Silicon = 1.1 eV
Eg of germanium = 0.75 eV
C.B = Conduction Band
V.B = Valence Band
Eg = Energy Gap
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