NOVA Online | Death Star | Tour the Spectrum: Radio

A Self-Guided Tour of the Electromagnetic Spectrum

Radio
Welcome to the radio portion of the electromagnetic spectrum. The wavelengths of radio waves are long compared to other types of electromagnetic waves—they range in length from 10,000 kilometers to less than a meter.

Human-made radio waves are generated when electrons, which are negatively charged, move back and forth within an antenna. This movement of charged particles creates a field that radiates out from the antenna at the speed of light.

The radio portion of the electromagnetic spectrum is divided into bands. Some bands are dedicated to commercial, government, aviation, and maritime purposes. Other bands are saved for two-way radios, radios, such as those pictured here.

Television stations use radio waves to broadcast their signals through the air, just as broadcast radio stations do. In fact, the TV band for channels 2-6 is next to the FM radio band. If you could tune your FM radio to just below 88 megahertz, you would pick up and hear the audio transmission from channel 6.

Next: Microwave

intro | radio | microwave | infrared | visible light | ultraviolet | x-ray | gamma

About The Scale
The scale at the top of this page distinguishes the different forms of electromagnetic radiation by wavelength, as measured in meters. Wavelength is the distance a wave moving at the speed of light travels during one cycle—from positive, to negative, and back to positive.

The numbers on the scale are in scientific notation. On this scale, 100 equals 1 meter (m). Moving to the left, 10¹=10m, 10²=100m, 10³=1,000m, etc. Moving in the other direction, 10^-1=0.1m; 10^-2=0.01m, 10^-3=0.001m, etc.

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