Description

The flow of electrical charge is referred to as electric current. There are two types of current, direct current (DC) and alternating current (AC). DC is current that flows in one direction with a constant voltage polarity while AC is current that changes direction periodically along with its voltage polarity. Thomas Edison and Alessandro Volta were pioneers in DC and wrote much of electricity's history. But as societies grew the use of DC over long transmission distances became too inefficient. Nikola Tesla changed all that with the invention of alternating current electrical systems. With AC it is possible to produce the high voltages needed for long transmissions. Therefore today, most portable devices use DC power while power plants produce AC.
This book may give you:

• Industrial Electrical Basics: What Are The 3 Basic Types Of Electrical Circuits?
• Electrical Basics: What Is Basic Electrical Knowledge?
• 
  Engineering Basics: What Are The 4 Basic Units Of Electricity?