http://www.ck12.org Chapter 23. Electricity
23.4 Electronics
Lesson Objectives
- Describe electronic signals.
- Identify types of electronic components.
- Explain how computers use electronics.
Lesson Vocabulary
- electronics
- semiconductor
Introduction
Electric devices, such as lights and household appliances, change electric current to other forms of energy. For
example, an electric stove changes electric current to thermal energy. Other common devices, such as mobile phones
and computers, use electric current for another purpose: to encode information. The use of electric current for this
purpose is calledelectronics.
Electronic Signals
Did you ever make a secret code? One way to make a code is to represent each letter of the alphabet by a different
number. Then you can send a coded message by writing words as strings of digits. This is similar to how information
is encoded using an electric current. The voltage of the current is changed rapidly and repeatedly to encode a
message, called an electronic signal. There are two different types of electronic signals: analog signals and digital
signals. Both are illustrated inFigure23.20.
- A digital signal consists of pulses of voltage, created by repeatedly switching the current off and on. This
type of signal encodes information as a string of 0s (current off) and 1s (current on). This is called a binary
("two-digit") code. DVDs, for example, encode sounds and pictures as digital signals. - An analog signal consists of continuously changing voltage in a circuit. For example, microphones encode
sounds as analog signals.