Back to: BASIC TECHNOLOGY JSS3
Welcome to class!
In today’s class, we will be talking about basic electronics. Enjoy the class!
Basic Electronics: Basic Emission Theory
Electron emission
As our introduction, we must understand that electric current can flow or move as a result of mobile electrons.
The electron in the outer shell which are weakly bound to the nucleus can easily be forced out from the shell. These electrons are called free electrons and their movement is what results to an electric current; hence, an electric current is produced.
What then is electron emission?
This is the method by which electrons are set free or liberated from a conductor material or metal.
Methods of electron emission
1. Thermionic emission:
This is the method of liberating electrons from the metal surface by the application of heat energy.
2. Photoelectric emission:
This is the method of setting free the electrons by the use of light energy or light rays.
3. Cold-cathode emission:
This is a method by which free electrons are obtained or emitted from the surface of the metal by the application of electric or magnetic field energy.
4. Secondary emission:
This is a method of obtaining free electrons from a metal surface through the use of kinetic energy.
NOTE:
1. Transistors are made of semiconductor material. The commonly used semiconductor materials in electronics are:
- Germanium
- Silicon
2. Semiconductors can be made to have electronics as charge either as N-type or P-type. N and P stand for negative and positive charges.
3. When semi-conductors are placed side-by-side the following types of transistors could be formed:
- P-N junction transistor
- P-N-P junction transistor
- N-P-N junction transistor
4. The process of supplying electrical power into junction transistor is known as BIASING. The appropriate source should be D.C (Direct Current).
Criteria for making transistor to be active
- Collector: Base junction should be reverse biased.
- The Emitter: Base junction should be forward biased.
In our next class, we will be talking about BASIC ELECTRONICS COMPONENTS. We hope you enjoyed the class.
Should you have any further question, feel free to ask in the comment section below and trust us to respond as soon as possible.
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The student at this level will be interested in knowing the meaning of electrons. how do we explain it to them in clear terms