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Circuit Fundamentals

Electrical Circuit Fundamentals And Electrical Devices

This topic is all about the electrical circuit fundamentals and electrical devices. It is first necessary to know about the basic terms used in electrical circuit study.


All other electrical engineering branches are derive from the two fundamental theories. i.e. Electric circuit theory and electromagnetic theory. Numerous branches of electrical engineering, e.g Power, Electric Machines, Control Systems, Electronics, Communications and Instrumentation depends on electric circuit theory. Therefore, Basic circuit theory (Circuit Fundamentals) is the most important course for electrical engineers to learn.

In electrical engineering, we transfer/convert energy from one form to another to get our desired output. This requires an interconnection of electrical devices. Such interconnection is referred to as an electrical circuits and those interconnected devices are known as circuit devices.

“An electric circuit is an interconnection of electrical circuit devices”

We utilize electrical circuits in various electrical system to achieve different tasks. Our major concern is to examination and analysis of the electrical circuits. By the analysis of a circuit, we mean to study that how do the interconnected elements and devices in the circuit interact?

Before going deep in overview of basic electrical circuit fundamental elements, we should know that there are two types of electrical circuit elements: passive electrical elements and active electrical elements. Passive electrical elements are those which dissipates energy i.e. resistor, capacitor and inductor etc. Active  electrical elements are those which are capable of delivering energy i.e. generators, batteries and operational amplifiers. Those active elements are further classified into two categories i.e. dependent sources and independent sources.

Ideal Independent Source

“An ideal independent source is an active element that gives a specified voltage or current that is totally independent of other electrical circuit elements”

independent electrical source - electrical circuit fundamentals
Independent voltage source

Ideal Dependent Source

“An ideal independent current source is an active element that gives a specified current totally independent of the other electrical voltage across the source”

independent current source - electrical circuit fundamentals
Independent current source

“An ideal dependent (controlled) source is a active element in which the source quantity is controlled by another voltage or current”

ideal dependent source - electrical circuit fundamentals
a) Dependent voltage source
         b) Dependent current source

Note: Dependent sources are usually designated by diamond-shaped symbols.

There are four possible types of dependent sources.

  • A voltage controlled voltage source (VCVS)
  • A current controlled voltage source (CCVS)
  • A voltage controlled current source (VCCS)
  • A current controlled current source (CCCS)

Read out the following topics to get the basic knowledge about electrical circuit fundamentals and electrical devices.

Capacitor - Working Principle
Inductor - Working Principle
Diode - Working Principle
Transducers - Working Principle
Transistors - Working Principle
Rectifiers - Working Principle
Relays - Working Principle
Electrical Circuits - Basic Principle
Electrical Laws
Circuit Analysis - Electrical Theorem