The word electronics is derived from electron mechanics, which means to study the behavior of an electron under different conditions of applied electric field.
Electronics definition
The branch of engineering in which the flow and control of electrons in vacuum or semiconductor are studied is called electronics. Electronics can also be defined as the branch of engineering in which the electronic devices and their utilization are studied.
The motion of electrons through a conductor gives us electric current. This electric current can be produced with the help of batteries and generators.
The device which controls the flow of electrons is called electronic device. These devices are the main building blocks of electronic circuits.
Electronics have various branches include, digital electronics, analog electronics, micro electronics, nanoelectronics, optoelectronics, integrated circuit and semiconductor device.
History of electronics
Diode vacuum tube was the first electronic component invented by J.A. Fleming. Later, Lee De Forest developed the triode, a three element vacuum tube capable of voltage amplification. Vacuum tubes played a major role in the field of microwave and high power transmission as well as television receivers.
In 1947, Bell laboratories developed the first transistor based on the research of Shockley, Bardeen and Brattain. However, transistor radios are not developed until the late 1950’s due to the existing huge stock of vacuum tubes.
In 1959, Jack Kilby of Texas Instruments developed the first integrated circuit. Integrated circuits contain large number of semiconductor devices such as diodes and transistors in very small area.
Advantages of electronics
Electronic devices are playing a major role in everyday life. The various electronic devices we use in everyday life include
- Computers
Today, computers are using everywhere. At home, computers are used for playing games, watching movies, doing research, paying bills and reservation of tickets for railways and airlines. At school, students use computers to complete their assignments.
- Mobile phones
Mobile phones are used for variety of purposes such as for sending text messages, making voice calls, surfing internet, playing games, and listening songs.
- ATM
ATM is an electronic telecommunication device particularly used for withdrawing money at any time from anywhere. ATM stands for automated teller machine. The customer can withdraw money up to a certain limit during anytime of the day or night.
- Pen drive
Pen drive is particularly used for storing large amount of data and also used for transferring data from one device to another. For example, the data stored in the computer can be transferred to the pen drive. The data stored in this pen drive can be retrieved at anytime.
- Television
Television is an electronic device primarily used for entertainment and knowledge. It is used for watching movies for entertainment, news for knowledge, cartoons for children’s.
- Digital camera
Digital camera is a camera used for taking pictures and videos. This images and videos are stored for later reproduction.
Electron emission from metal
Electron emission definition
Generally, emission refers to a process by which any object becomes free. In the similar way, the process by which the free electrons becomes free from the metal and enters into the vacuum is called electron emission.
Atom
We know that every solid, liquid, and gas is made up of atoms. The size of these atoms is very small. These atoms consist of even smaller particles such as protons, electrons, and neutrons.
The strong nuclear force between the neutrons and protons makes them stick together to form a nucleus at the center of an atom. Protons have positive charge and neutrons do not have any charge. Hence, the overall charge of a nucleus is positive.
Electrons are the negatively charged particles, which continuously revolve around the nucleus of an atom. These electrons are revolving around the nucleus of an atom because of the electrostatic force of attraction between the electrons and the nucleus.
Electrons revolve around the nucleus in different orbits or shells. The electrons, which are revolving at the outermost shell of an atom, are called valence electrons. The valence electrons and the atomic nucleus are present at greater distance. Hence, the electrostatic force of attraction present between the valence electrons and nucleus is very small. Thus, the valence electrons are loosely attached to the nucleus.
What is electron emission?
When a small amount of external energy is applied to the valence electrons, they gain enough energy and break the bonding with the parent atom. The electron, which breaks the bonding with the parent atom, moves freely from one place to another place. These electrons, which move freely within the metal, are called free electrons. However, these free electrons cannot escape from the surface of a metal.
It is because the free electrons in the metals do not have enough energy to escape from metal. The free electrons, which try to escape from the metal, are pulled by positive electric force of atomic nucleus towards the metal. Hence, free electrons cannot escape from metal without sufficient energy. Thus, the positive atomic nucleus of the metal opposes the free electrons, which try to escape from the metal.
In order to make the free electrons to escape from the metal, an additional external energy is required. This additional external energy is applied in the form of heat, electric field, or light.
When the external energy in the form of heat, light, or electric field is applied to the metal, the free electrons gain enough energy and break the bonding with the metal. Free electrons, which break the bonding with metal, will jumps into the vacuum. The free electrons in the vacuum are not associated with the metal.
The process by which, these free electrons break the bonding with metals and jumps into the vacuum is called electron emission. The amount of external energy required to remove an electron from the surface of a metal is called work function. Work function is measured in joules.
The free electrons in the vacuum have higher energy than the electrons that are revolving around the nucleus because the free electrons in the vacuum had gained additional energy from the source of heat or light.
The process of electron emission is somewhat similar to the ionization process. In ionization process, electrons are removed only from the atom and not from the metal whereas in electron emission process electrons are removed from the atom as well as from the metal.
Different methods of electron emission
The different methods to emit free electrons from the metal surface include:
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