20.4 Electronic Devices
Reading Focus
Key Concepts
How do electronic signals convey information?- How do vacuum tubes control electron flow?
- What are two types of semiconductors?
- How are semiconductors used?
- What are the benefits of using microchips in communication devices?
Vocabulary
electronics
electronic signal
analog signal
digital signal
semiconductor
diode
transistor
integrated circuit
computer
Reading Strategy
Summarizing Copy the table below. As you read, complete the table to summarize what you learn about solid-state components.
| Solid-State Component | Description | Uses |
|---|---|---|
| Diode | a. | b. |
| Transistor | c. | d. |
| Integrated circuit | e. | f. |
How do a toaster and a lamp use electric current differently than a computer or a mobile phone? The toaster and lamp are electrical devices. They change electrical energy into heat or light. The computer and mobile phone are electronic devices, which use electric current to process or send information.
Electronic Signals
The science of using electric current to process or transmit information is electronics. The information is carried by an electronic signal. An electronic signal is information sent as patterns in the controlled flow of electrons through a circuit.
To understand how this works, think about circuits. If a voltage source is connected to a circuit by a wire, electrons will flow through the wire. Controlling the electron flow by either altering the voltage or turning the current on and off produces a coded signal. 
Electronics conveys information with electrical patterns called analog and digital signals.
Figure 16 A computer uses electric current to process information. A toaster uses electric current to change electrical energy into thermal energy.
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