Home > Encyclopedia of Science > Electromagnetic Spectrum

• Wavelength and frequency
• Regions of the electromagnetic spectrum
• Words to Know
• Applications

The term electromagnetic spectrum refers to all forms of energy transmitted by means of waves traveling at the speed of light. Visible light is a form of electromagnetic radiation, but the term also applies to cosmic rays, X rays, ultraviolet radiation, infrared radiation, radio waves, radar, and microwaves. These forms of electromagnetic radiation make up the electromagnetic spectrum much as the various colors of light make up the visible spectrum (the rainbow).

Wavelength and frequency

Any wave—including an electromagnetic wave—can be described by two properties: its wavelength and frequency. The wavelength of a...