Figure 9 The electromagnetic spectrum consists of radio waves, infrared rays, visible light, ultraviolet rays, X-rays, and gamma rays.
Interpreting Diagrams Which waves of the electromagnetic spectrum have the longest wavelengths?
Today, radiation beyond the red end of the color band is called infrared radiation. Herschel experimented with infrared radiation and found it had many of the same properties as visible light. With these experiments, Herschel opened the door to the study of invisible types of electromagnetic radiation.
The full range of frequencies of electromagnetic radiation is called the electromagnetic spectrum. Figure 9 shows the spectrum of electromagnetic radiation in order of increasing frequency from left to right. Visible light is the only part of the electromagnetic spectrum that you can see, but it is just a small part. 
The electromagnetic spectrum includes radio waves, infrared rays, visible light, ultraviolet rays, X-rays, and gamma rays. Each kind of wave is characterized by a range of wavelengths and frequencies. All of these waves have many useful applications.
What is the full range of frequencies of electromagnetic radiation called?
Radio Waves
Radio waves have the longest wavelengths in the electromagnetic spectrum, from 1 millimeter to as much as thousands of kilometers or longer. Because they are the longest waves, radio waves also have the lowest frequencies in the spectrum—300,000 megahertz (MHz) or less. Radio waves are used in radio and television technologies, as well as in microwave ovens and radar.
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