Complete Electronics Self-Teaching Guide with Projects

Chapter 5

AC Pre-Test and Review

You need to have some basic knowledge of alternating current (AC) to study electronics. To understand AC, you must understand sine waves.

A sine wave is simply a shape, like waves in the ocean. Sine waves in electronics are used to represent voltage or current moving up and down in magnitude. In AC electronics, some signals or power sources (such as the house current provided at a wall plug) are represented by sine waves. The sine wave shows how the voltage moves from 0 volts to its peak voltage and back down through 0, its negative peak voltage, at 60 cycles per second, or 60 Hertz (Hz).

The sound from a musical instrument also consists of sine waves. When you combine sounds (such as all the instruments in an orchestra), you get complex combinations of many sine waves at various frequencies.

The study of AC starts with the properties of simple sine waves and continues with an examination of how electronic circuits can generate or change sine waves.

This chapter discusses the following:

• Generators
• Sine waves
• Peak-to-peak and root mean square voltages
• Resistors in AC circuits
• Capacitive and inductive reactance
• Resonance