Electromagnetic Spectrum

Copyright © 2005 Dave Whitmore

 

Wavelength and frequency have an inverse relationship to each other. In other words, as the wavelength gets longer the frequency gets lower. There's a fairly simple relationship between frequency and wavelength:

λ = c/f

where λ is the wavelength, c is the velocity of light (3 x 108 meters/second) and f is the frequency in hertz.

Since we're dealing with very large and very small numbers scientific notation is required to represent the quantities. Here are some shortcuts:

1 nanometer (nm) = 10-9 meters
1 micron = 10-9 meters
1 kilohertz (kHz) = 103 hertz
1 metahertz (MHz) = 106 hertz
1 gigahertz (GHz) = 109 hertz
1 terahertz (THz) = 1012 hertz

 

Here are some wavelength and frequency data to give a perspective on the relationships.

 
λ (meters)
f (Hertz)
Radio
> 10-1
<= 3 x 10-9
Microwave
10-3 to 10-1
3 x 109 to 3 x 1011
Infrared
7 x 10-7 to 10-3
3 x 1011 to 4 x 1014
Visible Light
4 x 10-7 to 7 x 10-7
4 x 1014 to 7.5 x 1014
Ultraviolet
10-8 to 4 x 10-7
7.5 x 1014 to 3 x 1016
X-Ray
10-11 to 10-8
3 x 1016 to 3 x 1019
Gamma Ray
< 10-11
>3 x 1019

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