Electrical Circuit Concepts | Electrical Source | Circuit Element

Electrical Circuit or Network

In Electrical circuit or network, a number of electrical connecting sources and loading devices are connected. It has a different path through which electrical currents (electron) pass.

Let’s check the Electrical Sources and Loading Devices one by one.

 Electrical Sources

For the generation of energy, we are using multiple energy sources and technologies. Now a day’s, advanced technology helps to generate electricity.

Electricity is produced from many different electrical energy sources. Some of these energy sources are renewable and others are non-renewable.

Different Types Of Electrical Sources

Sources supply electrical energy to produce the current and potential difference (voltage) in the circuit.

According to the electrical sources are divided into two different categories.

1. Voltage source

The voltage source is also classified into two types.

  • Ideal Voltage source
  • Practical Voltage source

2. Current source

Classification of current source into two parts.

  • Ideal Current source
  • Practical Current source

The classification chart of the electrical energy source is…

Moreover, students are confusing about the “What is the difference between Voltage Source and Current Source?“.

Due to the confusion and lack of basic circuit knowledge, they do not properly work and understand in the practical study

Let’s the study of both sources in details.

Voltage Source (Ideal & Practical)

A voltage source is a device which generated and maintained the potentials in the circuit. And it is provided an accurate value of output load or others connecting source.

A voltage source is available in the form of a battery or generator.

It is classified into two types –

  • Ideal voltage sources
  • Practical voltage source

To study each part with details explanation.

1. Ideal Voltage Source

The ideal voltage source is known as “an Independent Voltage Source”. Because the source which provides a constant terminal voltage across any variation of load.

Representation of the ideal voltage source in the circuit,

The most important things, the internal resistance of an ideal voltage source is zero. Due to the zero internal resistance, the input voltage source(Vin) and load voltage (Vout) is the same.


An Ideal voltage source value is calculated by the following formula.

Volatge Source,  VS = VL = (IL*RL)


‘VS’ – Voltage Source
‘VL’ – Load Voltage
‘IL’ – Load Current
‘RL’ – Load Resistance

The second part is…

2. Practical Voltage Source

Practical Voltage Source is also known as “Dependent Voltage Source” or “Controlled Voltage Source”.

In a practical study, it has a terminal load voltage. Sometimes, it is decreased by changing the load or electrical resistance.

The symbolic representation of practical voltage source looks like,


To calculate the value of a practical voltage source.

VL= VS - (I*RS)


‘RS’ is the Resistance Source.

V-I Characteristic Of Voltage Source

An ideal and practical voltage source are characterized by internal resistance (Rs) which is in voltage source shown in the following diagram.

The diagram of the V-I  characteristic of the Ideal and Practical voltage source.

Ideal and Practical current source

V-I Characteristic of Voltage Source

The V-I characteristic of an ideal voltage source is represented by the constant position due to the internal resistance (Rse=0).

And Practical voltage source characteristic shows the voltage drop by decreasing resistance or the changing resistance.

This is the explanation of the voltage source.

Current Source (Ideal & Practical)

The current source can be classified into two part,

  • Ideal Current Source
  • Practical Current Source


1. Ideal Current Source

The source which provides a constant current to the load by changing the across load voltage (VL) or resistance (RL) this source is known as the “Ideal Current Source”.

It is basically known as “Independent Current Source”.

This current source is symbolic shows by the arrow inside the circle.

Practical study represent as, Source current (IS) = Load current (IL)


Calculating the value of the ideal current source is

Current Source, IS = IL = (VL/RL)


IS – Source Current

IL – Load Current

VL – Load Voltage

RL – Load Resistance

2. Practical Current Source

In the practical study, source current is not getting the same load current due to the different load or variable resistance.

The diagram of the Current Source,

V-I Characteristic Of Current Source

In the practical study, the current source provided load current which decreases with increasing load voltage and also increasing the internal resistance (Rp).

In the relation between the voltage and current characteristic, you can get variable or drop voltage.

Look ahead, V-I characteristics of Ideal and Practical current source

Ideal and Practical current source

V-I Characteristics of Current Source

What is Electrical Load?

The electrical load is used to transform and store energy to other applications.

It is classified into different types like inductive, resistive or capacitive in the form of the various electrical and electronic application. For example, Motors, Lamp or light, Heater, etc.

Image result for electric load

Electrical Circuit (with the Load)

From the above diagram, various loads can connect at terminal across the voltage source. It opposes to the voltage source for the consuming or supplying the electrical power.

When load connects with supply source or flowing of the current in the circuit to form a closed circuit.

And at the no-load condition, the circuit will be occurring in the form of the open circuit. So, the zero current occurs at no load condition.

Electrical Circuit Element 

There are two types of the circuit elements used in the electrical circuit. It is classified into two part

  • Active Circuit Element
  • Passive Circuit Element

The main function of circuit elements is to control, store and consume the power by using the resistor, capacitor, and inductor (circuit elements).

These circuit elements are connected to the other component.

1. Active Element

The electrical elements which can be having own capability to produce the current in the circuit. This element is called “an Active Element”.

Active element helps to produce increasing the level of energy in the circuit.

It simply defines as ‘the source of electrical energy’. Moreover, It refers to Ideal current source and an Ideal voltage source.


Battery, Generator, Alternator, and other electronic components (LED, Diode, Transistor, Integrated circuit (IC’s), Vacuum tube) these are an example of the active elements.


Active elements

Example of Active Element (Source)

The circuit having at least a single active element for flowing current and producing the potential difference in given circuit.

2. Passive Element

In passive elements which do not produce own their energy. The elements which can be restricted, store and supply the energy to others from the input source is called “Passive Element”.

The passive element is opposite to the active element.  It occurs in the form of the loading device.

Resistor, Capacitor, Inductor (coils), Switches, Voltmeter, Ammeter, Transformer these are the example of the Passive element.

Passive elements

Example of Passive Element

In passive circuit does not work due to the absence of sources. So, it must provide or connect the input power source.

3. Linear Element

Linear elements used to the passive element and bilateral element.

The passive element is said to be linear if their value is constant while any variation in voltage or current.

Resistor, Capacitor, Inductor, etc. these are the example of the linear circuit. These components have own capability to supply, store and maintain the circuit.

Linear Circuit (Source)

In the V-I characteristic of linear element shows current through the linear element is always directly proportional to the voltage across it.

4. Non-linear Element

All active element is a non-linear element.

The current flowing through the non-linear element (diode) is not directly proportioned to the voltage across it.

Non-Linear Circuit (Source)

From the above V-I characteristic, the current is inversely proportioned to the voltage.

5. Unilateral Element

The element which allows the current in only one direction (Uni direction) in the circuit is called “Unilateral Element”.

The diode is the best example of the unilateral element.

Unilateral CircuitUnilateral Circuit

6.Bilateral Element

The bilateral element which used to flow in both direction in the circuit. This circuit looks like…

Bilateral Circuit

Bilateral Circuit

The transmission line is the best example of the bilateral element. Because current can flow in any direction but the not particular single path.


Electrical Circuit

Classification of the electrical circuit is basically divided into two categorize. It’s naming as,

  • Series Circuit
  • Parallel Circuit

Dive into two parts,

1. Series Circuit

The circuit consists of various elements in a single path for flowing same electrical current is known “Series Circuit”.

In the series circuit, the same current flowing through the elements ( may be a source or load element)

Equivalent Current,

Calculating the equivalent value of components in the series circuit.


Ieq = I1 = I2 = I3 =......= In









These are the calculation of the different elements of the equivalent series circuit.

2. Parallel Circuit

The number of elements is connected in parallel form is called “Parallel Circuit”.

The voltage across each element is the same. But they have different current in it.

It having one or more path for flowing electron with the different value of currents. Total voltage across the component is,

Veq = V1 = V2 = V3 =........= Vn


Ieq= I1 + I2 + I3 +.......+In




Leq= (1/L1) + (1/L2) + (1/L3) +....... + (1/Ln)


Ceq = C1 + C2 + C3 + ......+ Cn

These are all about the electrical circuit element.

Basic Electrical Circuit Concepts

To study of other related concepts of electric circuits.

1. Branch

The various paths of the circuit which consist of only one circuit element between two terminal is known as “Branch”.

From the following figure, three branches represented single elements such as resistor ‘R1’, voltage source ‘VS’ and current source ‘IS’.

2. Node                                                                                                                                                         

A point at which two or more elements are joints together is called “Node”. Node refers to two or more branches.

3. Junction

A point in the circuit at which three or more branches are joint together is called as “Junction”.

Thus all junction are a node but all node cannot be the junction. Node is present in the center of the junction.

4. Loop

A set of branches which forms a closed path or circuit. It is formed by the Branches.

5. Mesh

Mesh is types of the loop. But loop does not occur in the mesh. All meshes are loops and all loops do not mesh.

The above figure helps to easily understand the basic concept of the electrical circuit.

In this tutorial, I try to cover all the basic concepts of electrical circuits.

If you have any query, feel free to write in the comment section below.

Thanks for Reading!

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