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Why Electronics?

Electronics has become an inseparable part of our life. We cannot imagine a single moment without it when we are not using any electronic device. We are woken up by set alarm clock, then the tea/coffee maker, remote control to turn on the TV, water heater, oven, move out of house use lift them the automated vehicle, office automation….uff..endless list goes on. Electronic equipment may be anything like a simple calculator to home appliances or up to sophisticated satellites. Any electronic equipment is made of electronic circuit. Electronic circuit is  connecting different basic electronic components together.

Just as for writing a book, knowledge about sentence writing, words and alphabet needed. Similarly, understanding of basic electronics components about its functioning, properties is essential prior to designing any electronic device.

What is electronics?

The Word electronics is motion of electrons in a material. It deals with study about flow and control of electrons under different electric condition.

Let us understand basic concepts and  basic electronic components. Basic concepts are electric charge, current voltage etc. and basic components like resistance, capacitors, inductors, battery etc.

Basic concepts

Electric charge

What is an Electric Charge?

Let us first understand the structure of an atom with help of Bhor model as in fig below.

An atom constitute of three basic particles like electrons (e), protons (p) and neutrons (n). The central part of an atom known as nucleus contains neutrons and protons. The outer part constitute of electrons revolving the nucleus in definite orbit. This structure is similar to the solar system; nucleus resembles sun while orbiting electrons are the planets. There are two types of forces gravitational and centrifugal exerted on electrons due to which electrons revolve in one particular orbit. Electric charge on electrons is negative, protons is positive while neutrons have no charge. Number of electrons is equal to number of protons. An atom as a whole is electrically neutral.As number of positive and negative charges are equal.

For better understanding, consider material silicon, which has atomic number of 14. It has an electronic configuration, distribution of number of electrons in different shells or orbits, denoted as K,L,M etc. Silicon with atomic number 14, electrons are distributed as K=2, L=8 and M=4. Number of electrons in last shell also known as valence electrons; in this case, it is 4. If valence electron is able to gain more energy than the forces acting on it, it breaks the forces and moves out of the orbit. Usually valence electrons require less energy to free itself compared to electrons in inner orbits. These valance electrons, which free themselves, now called as free electrons. Such free electrons are negatively charged and move freely within the material. An atom depleted of electrons is termed as positive ion.  An ion is fixed or immobile, while free electrons move around within the material.

Definition:  An Electric charge is physical property of any matter to experience a force when placed under any electromagnetic field.

Symbol    Q

SI unit   Coulomb (C)

Types of charges:

Electrons are negatively charge Q_ or  -e = -1.69×10 ^-19 C

Protons are positively charged Q+  or +e = + 1.69×10^-19 C