Introduction to Electronics | Fundamentals of Electronic Circuits | Lesson 1

Electronics is a field of engineering and physics that deals with the study, design, development, and application of electronic devices, circuits, and systems. Electronics is concerned with the manipulation of electrons and their behavior in various materials and devices to create, control, and transmit information or energy.

Electronic devices include components such as transistors, diodes, resistors, capacitors, and integrated circuits, which are used to build electronic circuits. Electronic circuits can range from simple circuits like a flashlight to complex circuits like a microprocessor.

Electronics plays a crucial role in modern society, with applications in communication systems, computers, medical equipment, entertainment devices, transportation systems, and many more areas.


The atom is connected to electronics in several ways. Electronics deals with the behavior of electrons in materials and devices, and the atom is the basic unit that makes up all matter, including the materials used in electronic devices.

In electronic devices, the behavior of electrons in materials determines their electrical properties, such as conductivity, resistance, and capacitance. These properties are related to the arrangement and behavior of electrons in the atoms that make up the material.

For example, in a conductor like copper, the outermost electrons of copper atoms are loosely bound to the nucleus, allowing them to move easily through the material and conduct electricity. In contrast, in an insulator like glass, the outermost electrons are tightly bound to the nucleus, making it difficult for them to move and preventing the material from conducting electricity.

In addition, electronic devices make use of electronic transitions within atoms to generate or detect light, as in LEDs and photovoltaic cells. Devices such as transistors and diodes rely on the behavior of electrons in a semiconductor material, which is a material with properties between those of conductors and insulators.

Thus, the study of electronics involves an understanding of the behavior of electrons in materials, which is ultimately rooted in the behavior of electrons in atoms.

The Bohr Model of Atom

The Bohr Model of Atom
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The Bohr model of the atom, also known as the Bohr-Rutherford model, was proposed by Niels Bohr in 1913 to explain the structure of the hydrogen atom.

The Bohr model is based on the assumption that electrons in atoms occupy discrete energy levels, or shells, rather than moving continuously around the nucleus. In the model, the electrons orbit the nucleus in circular paths, similar to the way planets orbit the sun. Each energy level is associated with a specific amount of energy, and electrons can move between levels by absorbing or emitting energy.

The model also includes several key postulates:

  1. The electrons can only occupy certain discrete energy levels, which are quantized.
  2. Electrons in an atom emit or absorb energy in the form of electromagnetic radiation when they move between energy levels.
  3. Electrons can exist only in certain orbits, or shells, around the nucleus. Each shell corresponds to a specific energy level, and shells farther from the nucleus have higher energy levels.
  4. Electrons in the inner shells have lower energy levels than those in outer shells.

The Bohr model was an important early step in the development of modern atomic theory, and it helped to explain the structure and behavior of simple atoms like hydrogen. However, it has some limitations and is not a complete description of the atom. In particular, the model does not account for the phenomenon of electron spin, which is necessary to explain the magnetic properties of atoms and molecules.

Why the Bohr Model?

The model of the atom that is typically used in electronics is the Bohr model, which was proposed by Niels Bohr in 1913. The Bohr model describes the atom as a small, positively charged nucleus surrounded by negatively charged electrons that orbit the nucleus in discrete energy levels or shells.

In electronics, the behavior of atoms is of particular interest when it comes to the interaction between electrons and the atoms of a material. The electronic properties of materials are determined by the arrangement of atoms and the behavior of the electrons in the outermost energy level, which is known as the valence level. By understanding the behavior of electrons in different materials, engineers and scientists can design and develop electronic devices with specific properties and capabilities.

The Atomic number

The atomic number of an element is based on the number of protons in the nucleus of an atom of that element.

Each element is defined by the number of protons in its atomic nucleus. For example, the element hydrogen has one proton in its nucleus, and the element carbon has six protons in its nucleus. The atomic number is represented by the symbol “Z” and is always a whole number.

The number of protons in an atom’s nucleus determines the element to which it belongs. Atoms with the same number of protons are of the same element, while atoms with different numbers of protons are of different elements.

The atomic number is a fundamental property of an element and is used to organize the elements in the periodic table. The elements are arranged in increasing order of their atomic numbers, and this arrangement reveals important patterns and trends in the properties of the elements.

In a neutral atom, the number of protons is equal to the number of electrons. This is because an atom is electrically neutral, meaning that it has no overall electric charge. The positive charge of the protons in the nucleus is balanced by the negative charge of the electrons in the electron shells surrounding the nucleus.

For example, a neutral atom of oxygen has eight protons in its nucleus, and therefore it also has eight electrons orbiting the nucleus. The electrons occupy different energy levels or shells around the nucleus, and the number of electrons in the outermost shell determines the atom’s chemical behavior and properties.

It is important to note that in ions, the number of protons and electrons is not always equal. An ion is an atom or a molecule that has gained or lost one or more electrons and therefore has a net electrical charge. For example, a positive ion or cation has lost one or more electrons, and a negative ion or anion has gained one or more electrons.

Material use in Electronics
There are a variety of materials that are commonly used in electronics, including:

  1. Silicon: Silicon is the most widely used material in electronics and is the basic material used to make computer chips, transistors, and other electronic components.
  2. Copper: Copper is an excellent conductor of electricity and is used extensively in wiring and electrical connections.
  3. Aluminum: Aluminum is also a good conductor of electricity and is used in a variety of applications, including wiring, circuit boards, and electrical contacts.
  4. Gold: Gold is an excellent conductor of electricity and is used in applications where a high degree of reliability is required, such as in computer memory modules.
  5. Iron: Iron is used in the production of magnetic materials, such as inductors and transformers.
  6. Nickel: Nickel is used in the production of magnetic alloys, such as permalloy and mu-metal, which are used to shield electronic components from electromagnetic interference.
  7. Zinc: Zinc is used as a coating on steel and other metals to protect them from corrosion.
  8. Plastics: Plastics are used extensively in the housing and packaging of electronic components and devices.
  9. Glass: Glass is used in the production of display screens, optical fibers, and other applications that require high transparency and clarity.
  10. Ceramics: Ceramics are used in the production of insulators, capacitors, and other electronic components that require high-temperature stability and resistance to wear and tear.


  1. What is the most widely used material in electronics?
    A) Copper
    B) Gold
    C) Silicon
    D) Iron

Answer: C) Silicon

  1. What is the atomic number of an element based on?
    A) The number of protons in the atom’s nucleus
    B) The number of neutrons in the atom’s nucleus
    C) The number of electrons in the atom’s nucleus
    D) The number of electrons in the atom’s electron shells

Answer: A) The number of protons in the atom’s nucleus

  1. Why is silicon important in electronics?
    A) It is abundant and low-cost
    B) It is chemically stable and reliable
    C) It has unique semiconducting properties
    D) All of the above

Answer: D) All of the above

  1. What is the model of the atom that is typically used in electronics?
    A) Quantum model
    B) Rutherford model
    C) Bohr model
    D) Dalton model

Answer: C) Bohr model

  1. What is a neutral atom?
    A) An atom with no electrons
    B) An atom with no protons
    C) An atom with no neutrons
    D) An atom with an equal number of protons and electrons

Answer: D) An atom with an equal number of protons and electrons

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