# 3 Basic Direct Current Circuit Theory

A direct current circuit is energized by dc electricity sources, such as battery connected by conductor wire through one or more source and electrical elements.

In order to make the application of dc electricity, we need a dc circuit.

## Direct Current Circuit Theory

Direct current has unidirectional (one direction) electric charge flow. This type of current can be obtained from a rectified alternating current source or dc source like a battery.

A dc source has many applications such as recharging the battery for supplying various application such as electric system, motor, and many more.

This circuit consists of a constant value of electric voltage and electric current. The value themselves are not affected by the time-changing variable.

In order to understand the dc circuit theory very well, make sure to read these below in order :

Make sure you have read what is electric circuit first to understand later material.

## Simple DC Circuit

A battery connected to a light bulb using a conducting wire will be a simple flashlight circuit.

The electric current flows from a positive terminal to light bulb and flowing through back to the negative terminal, making an endless loop.

This basic principle will lead to various application of dc circuit.

 Figure 1. Simple dc circuit application

You will find these elements in electrical circuits:

• Circuit elements
• Nodes, branches, and loops
• Series resistor
• Parallel resistor
• Wye delta transformation

## Electric Circuit Basic Laws

For analyzing an electric circuit, we need the two most basic laws. These laws will be used for other electric circuit analysis methods and advanced theorems. These laws will also be used in analyzing the ac circuit:
• Ohm’s Law
• Kirchhoff’s Laws

## Analysis Method DC Circuit

After a few years, the electric circuit has been developed into many applications and types related to its function and purpose.

Thus, we need to learn about the analysis method of an electrical circuit, especially the dc circuit, such as :

• Node Analysis
• Supernode Analysis
• Mesh Analysis
• Supermesh Analysis

## Analysis Theorem DC Circuit

The analysis methods of the dc circuit above may not sufficient to analyze a complex circuit.

Therefore, we need to learn about analysis theorem of dc circuit below :

• Superposition
• Source Transformation
• Thevenin’s Theorem
• Norton’s Theorem
• Maximum Power Transfer

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