Electromagnetic Spectrum

  You can read more about the spectrum at NASA's Observatorium Education site.
Click on the thumbnail to view the geometry of an electromagnetic wave.

Free-Space Wavelength

Frequency

Type

> 1 m

< 300 MHz

Radio (AM, FM, TV)

30 cm ® 1 mm

109 ® 3x1011 Hz

Microwaves

1 mm ® 780 nm

(1000 m m ® 0.78 m m)

3x1011 ® 3.8x1014 Hz

Infrared [IR]

780 nm ® 390 nm

(0.78 m m ® 0.39 m m)

3.8x1014 ® 7.7x1014 Hz

Visible

390 nm ® 60 nm

7.7x1014 ® 5x1015 Hz

Ultraviolet [UV]

100 Å ® 0.001 Å

3x1016 ® 3x1021 Hz

X-Rays

< 1 Å

> 3x1018 Hz

Gamma Rays

(from nucleus or matter-to-energy conversion)


Visible Spectrum
The majority of the frequencies in the visible spectrum appear reddish to our eyes. That is, the red band is the widest band. In contrast, the yellow band is very narrow. The table and colored plot below categorize the colors by wavelength (assuming the light is traveling in air). The plot is a bit misleading because our eyes are not equally sensitive to all the colors. The sensitivity peaks right near the green-yellow wavelengths and falls off at the red and violet wavelengths. (As a result, the violet and red bands in a rainbow will not usually appear as wide as shown in the plot simply because we don't see the longer red wavelengths and shorter violet wavelengths as well as the other wavelengths.)
ColorWavelength Range (nm)
Red 622 - 780
Orange 597 - 622
Yellow 577 - 597
Green 492 - 577
Blue 455 - 492
Violet 390 - 455


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