Radio Waves and Electromagnetic Spectrum

Overview

This lecture covers the properties of radio waves, how they differ from sound waves, and their everyday uses in communication technologies.

Electromagnetic waves are ordered by increasing wavelength: visible light, infrared, microwave, and then radio.
Radio waves have wavelengths longer than 10 centimeters, making them the longest in this context.
All listed waves—visible, infrared, microwave, radio—are types of light (electromagnetic waves), not sound waves.

Radio waves are not sound waves; they are electromagnetic waves.
The sound heard from a radio is not the radio wave itself but a decoded signal transmitted by radio waves.
Radio signals are sent from a tower to a receiver (e.g., a radio or boombox) which decodes the information.
Devices that use radio or similar waves for communication include radios, walkie talkies, TVs, satellites, and cell phones.
Cell phones and Wi-Fi often use microwave frequencies, which are also electromagnetic waves.

Most microwaves and radio waves are low energy and not dangerous to humans.
Cell phones and Wi-Fi do not use the specific microwave wavelengths that can heat or cook materials.
Longer wavelengths (like radio) have lower frequencies and lower energies, making them generally safe.

Radio Waves — Electromagnetic waves with wavelengths longer than 10 centimeters, used for wireless communication.
Electromagnetic Wave — A type of energy wave, such as light, that travels through space and includes visible, infrared, microwave, and radio waves.
Decoder (Radio Receiver) — A device that converts encoded radio signals into sound or usable information.
Microwave — Electromagnetic waves with wavelengths shorter than radio waves but longer than infrared, also used for communication.

Review the electromagnetic spectrum and identify examples of each type of wave.
Prepare to discuss other real-life applications of electromagnetic waves in the next class.