ARRL Technician Practice Exam

What is a usual name for electromagnetic waves that travel through space?

1. Radio waves

2. Microwaves

3. Infrared waves

4. X-rays

The correct answer is: Radio waves

Electromagnetic waves that travel through space are commonly referred to as radio waves. This term encompasses a wide range of frequencies and is often used to describe the waves that are used in various communication technologies, including broadcasting and amateur radio. Radio waves are part of the broader electromagnetic spectrum, which also includes microwaves, infrared waves, visible light, ultraviolet light, X-rays, and gamma rays. While all of these are forms of electromagnetic radiation, radio waves specifically are distinguished by their relatively low frequencies, which enable them to travel through the atmosphere and be utilized for long-distance communication. For example, radio waves have the ability to diffract around obstacles, allowing for signals to be received even when there are barriers in the way, which is a valuable property for communication. In contrast, the other types of electromagnetic waves mentioned, such as microwaves, infrared waves, and X-rays, have different applications and characteristics that make them suitable for different purposes, like cooking food, thermal imaging, and medical imaging, respectively.