INTRODUCTION:
Electronics is the branch of the
If we are thinking about electronics means is the flow of electrons, but if you think is it really that the electrons are flowing or not? if it is flowing then why the conductors are not becoming narrow? Why the conductors are not getting melt due to the heat energy inside the conductors? Then you will get mad and think is it really? Yeah, you have to think practically. Then wait I will clear your doubt. Actually, the electrons are not flowing inside the conductors always, always the charges are flowing which is also nothing but the electrons but also only the energy holds by the electrons. Yeah then now you have to ask the questions.
The electronics means how to control the flow of electrons or to move the electrons. This what we learned in out B.Tech engineering in the 1st semester named electron emission. If we provide sufficient energy to an electrode then the electrons in the outermost shell of the atom of that metal gain enough energy to erect from the surface of that metal or electrode. in short, the liberation of electrons from the surface of a substance are known as electron emission. There are basically 4 methods of producing electron emission are:
- Thermionic Emission.
- Photo-electric Emission.
- Secondary Emission.
- Field-effect emission.
- Thermionic Emission: All the materials are composed of atoms which in turn consist of a nucleus, made of protons and neutrons, surrounded by electrons. These electrons are distributed at various levels around the nucleus and thus possess different levels of energy. Now, imagine that we start heating a particular material. The thermal energy so supplied increases the kinetic energy of the electrons within the material. This causes them to overcome the force of attraction which exists between them and the protons within the respective nuclei. As a result, they get knocked-out from the material and will be liberated into space surrounding the material. More is the heat supplied, more are the number of electrons ejected. This phenomenon is known as thermionic emission i.e. emission of ions called thermions due to the thermal energy supplied, first it was observed by Thomas Alva Edison in 1883.
