Teach Yourself Electricity and Electronics, Sixth Edition, 6th Edition

2

CHAPTER

Electrical Units

LET’S LEARN ABOUT THE STANDARD UNITS THAT ENGINEERS USE IN DIRECT-CURRENT (DC) CIRCUITS. Many of these principles apply to common utility alternating-current (AC) systems as well.

The Volt

In Chap. 1, you learned about the volt, the standard unit of electromotive force (EMF), or potential difference. An accumulation of electrostatic charge, such as an excess or shortage of electrons, always occurs when we have a potential difference between two points or objects. A power plant, an electrochemical reaction, light rays striking a semiconductor chip, and other phenomena can also produce voltages. We can get an EMF when we move an electrical conductor through a fixed magnetic field, or when we surround a fixed electrical ...