http://www.ck12.org Chapter 5. Energy
A Spectrum of Electromagnetic Waves
Visible light and infrared light are just a small part of the full range of electromagnetic radiation, which is called the
electromagnetic spectrum. You can see the waves of the electromagnetic spectrum in theFigure5.88. At the top
of the diagram, the wavelengths of the waves are given. Also included are objects that are about the same size as the
corresponding wavelengths. The frequencies and energy levels of the waves are shown at the bottom of the diagram.
Some sources of the waves are also given. For a video introduction to the electromagnetic spectrum, go to this URL:
http://www.youtube.com/watch?v=cfXzwh3KadE.
FIGURE 5.88
- On the left side of the electromagnetic spectrum diagram are radio waves and microwaves. Radio waves have
the longest wavelengths and lowest frequencies of all electromagnetic waves. They also have the least amount
of energy. - On the right side of the diagram are X rays and gamma rays. They have the shortest wavelengths and highest
frequencies of all electromagnetic waves. They also have the most energy. - Between these two extremes are waves that are commonly called light. Light includes infrared light, visible
light, and ultraviolet light. The wavelengths, frequencies, and energy levels of light fall in between those of
radio waves on the left and X rays and gamma rays on the right.
Q:Which type of light has the longest wavelengths?
A:Infrared light has the longest wavelengths.
Q:What sources of infrared light are shown in the diagram?
A:The sources in the diagram are people and light bulbs, but all living things and most other objects give off infrared
light.
Summary
- Electromagnetic radiation travels in waves through space or matter. Electromagnetic waves with shorter
wavelengths have higher frequencies and more energy. - The full range of electromagnetic radiation is called the electromagnetic spectrum. From longest to shortest
wavelengths, it includes radio waves, microwaves, infrared light, visible light, ultraviolet light, X rays, and
gamma rays.
Vocabulary
- electromagnetic spectrum: Full range of wavelengths of electromagnetic waves, from radio waves to gamma
rays.