Electronics means study of flow of electrons in electrical circuits. The word Electronics comes from electron mechanics which means learning the way how an electron behaves under different conditions of externally applied fields. IRE – The Institution of Radio Engineers has given a definition of electronics as “that field of science and engineering, which deals with electron devices and their utilization.” Fundamentals of electronics are the core subject in all branches of engineering nowadays.

Application of Electronics
Electronics has made tremendous advancement during last few decades and our day to day life involves the use of electronic devices. Electronics has played a major role in every sphere of our life; this can be proved with the following application of electronics:

Entertainment and Communication
Availability of economical and fast means of communication paves the way for progress of a country. Few decades ago, the main application of electronics was in the field of telephony and telegraphy. Now, with the aid of radio waves we can transmit any message from one place to another, without the use of wires. 
Radio and TV broadcasting offers a means of both entertainment as well as communication. Today, Electronics gadgets are widely used for entertainment.

Defence Applications
Defence applications are completely controlled by electronic circuits. RADAR that is Radio Detection and Ranging is the most important development in electronics field. With the help of radar it is possible to detect and find the exact location of enemy aircraft. Radar and anti craft guns can be linked by an automatic control system to make a complete unit.

Industrial Application
Electronics circuits are widely being used in industrial applications such as control of thickness, quality, weight and moisture content of a material. Electronic amplifier circuits are used to amplify signals and thus control the operations of automatic door openers, power systems and safety devices. Electronically controlled systems are used for heating and welding in the industry. The most important industrial application is that the power stations which generate thousands of megawatts of electricity are controlled by tiny electronic devices and circuits.

Medical Services
Electronics systems are being used by Doctors and scientists in the diagnosis and treatment of various diseases. X-rays, ECG, Short eave diathermy units and oscillographs are some instruments which have been used so far in medical science. The use of electronics in medical science has grown so extremely and is useful in saving the life of mankind from a lot of sufferings.

Instrumentation – Application of Electronics
Electronics instruments such as cathode-ray oscilloscopes, frequency counters, signal generators, strain gauges are of great help in for precise measurement of various quantities. Without these electronic instruments no research laboratory is complete.
An Introduction to Electronic Components

All electronic circuits contain few basic components. That are three passive components and two active components. An Integrated circuit may comprise of thousands of transistors, few capacitors on a small chip.

Types of Electronic Components:
Passive Components
1. Resistors
2. Capacitors
3. Inductors

Active Components
1. Tube devices
2. Semiconductor devices

What are Passive Components?

Resistors, capacitors and inductors are called as passive components. These electronics components are called passive because they by themselves are not capable of amplifying or processing an electrical circuit. However, passive components are as important as active components in any electronic circuit.

Resistors:

The component that opposes the flow of current is called a resistor. This opposing force is called the resistance of the material. It is measured in ohms.
Capacitors: Capacitor is a component that is used to store electrical energy and release them whenever desired. It is measured in farads. Capacitors like resistors can either be fixed or variable. Some common capacitors are mica, ceramic, paper and air gang capacitors.

Inductor:
The electronic component which produces inductance is called an inductor. The inductance is measured in henrys (H). All inductors, like resistors and capacitors are listed as fixed and variable.

What are Active Components?

Active components are used in electronic circuits. They are classified in two categories: Tube devices and semiconductor devices. Due to many advantages of semiconductor devices, they are replacing tube devices in many electronic applications.

Electronics components and electronic applications are penetrated everywhere in our day to day life. Electronics deals in the micro and milli range of voltage, current and power and also control kilo and mega volts, amperes and watts. Today, Electronics is an established branch of engineering.