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Electrical Fundamentals - Introduction to Direct Current (DC) Theory

A. Bhatia, B.E.

Course Outline

A direct current (DC) is one in which the current does not change with time. This is in contrast to alternating current (AC), where the current changes continuously. In this 4-hour course, the readers will be introduced to the fundamentals of direct current (DC) theory, including in-depth coverage of Ohm's law and its relation to voltage, current, resistance and power. The course is followed by the practical applications of electrical circuits connected in series, parallel and combination.

The course material is based entirely on Naval Education and Training Materials (NAVEDTRA 14173), Electricity and Electronic Training Series; Module-1 "Introduction to matter, energy and direct current" and covers Chapter 3.

The text is arranged to let you progress at your own pace, and concepts and terms are introduced as you need them, with many detailed examples and illustrations. This course contains much of the material that forms the foundation of electrical knowledge.

This course includes a multiple-choice quiz at the end, which is designed to enhance the understanding of course materials.

Learning Objective

At the conclusion of this course, the student will be able to:

Intended Audience

This course is aimed at students, professional engineers, service technicians, energy auditors, operational & maintenance personnel, facility engineers and general audience.

Course Introduction

On a DC circuit, current flows in one direction only. Voltage can remain at a level or change, but it always has the same polarity. The main source of DC is from batteries, photocells, fuel cells, rectifiers and DC generators.

The most fundamental equation describing DC circuits is Ohm's Law. While doing experiments on how well metals conduct electricity, German physicist Ohm discovered the equation V = I * R, which is fundamental to both the DC and AC circuits as well. Knowing two items in this equation allows you to calculate the third.

DC circuits can be arranged in different ways. If component current has only one path to follow, it is connected in series. If there are two or more paths, the components are connected in parallel. Components may also be interconnected to provide both situations. These are called series-parallel combinations.

This course explains the DC circuits in simplified text and will be extremely helpful to individuals who require a basic knowledge of electrical principals and equipment to better their primary responsibilities.

Course Content

In this course, you are required to study Naval Education and Training Materials (NAVEDTRA 14173), Electricity and Electronic Training Series; Module-1 "Introduction to Matter, Energy and Direct Current" Chapter 3:

Introduction to Matter, Energy and Direct Current (Chapter 3, NAVEDTRA 14173)

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Course Summary

The DC circuits can be arranged in series, parallel and series-parallel combination circuits. The following rules apply to the respective circuits:

Series Circuit

Parallel Circuits

Series-Parallel Circuits


Once you finish studying the above course content, you need to take a quiz to obtain the PDH credits.

Take a Quiz

DISCLAIMER: The materials contained in the online course are not intended as a representation or warranty on the part of PDH Center or any other person/organization named herein. The materials are for general information only. They are not a substitute for competent professional advice. Application of this information to a specific project should be reviewed by a registered architect and/or professional engineer/surveyor. Anyone making use of the information set forth herein does so at their own risk and assumes any and all resulting liability arising therefrom.