AST 1002: Study Guide Table 8

AST 1002: "Study Guide" Table 8

[Sections Taught by Prof. H.L. Cohen]
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Last updated January 1, 2003

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Table 8

Table 8b

Table 8c

Table 19

Table 8. The Electromagnetic Spectrum
Designation⁽¹⁾ Wavelength
(nanometers)⁽²⁾ Frequency⁽³⁾
(lower limit) Photon
Energy Atmospheric
Transparency

Gamma Rays    < 0.1 nm   (Very Small) (Enormous) (Enormous) Very Poor

X Rays 0.1-10 nm Very Poor

Ultraviolet 10-380 nm Poor

Visible (Light)⁽⁴⁾ 380-750 nm ⁽⁵⁾ Excellent

   Violet 380-420 nm (Violet Wavelengths About 1/2 Red Wavelengths)

   Indigo⁽⁶⁾ 420-450 nm

   Blue 450-490 nm

   Green 490-570 nm

   Yellow 570-590 nm

   Orange 590-630 nm

   Red 630-750 nm (Red Wavelengths About 2 times Violet Wavelengths)

Infrared 750 nm-0.1 mm Poor

Microwave⁽⁷⁾ 0.1 mm-10 cm Fair to Good

Radio⁽⁸⁾ over 10 cm   (Very Large) (Small)
(less than 3,000 MHz) (Very Small) Very Good

   FM Radio 2.8-3.4 m 108-88 MHz (Poor over 10 m)

   AM Radio 190-560 m 1,600-540 MHz

Table Notes

All E-M radiation travels at the same speed through a vacuum (300,000 km/sec or 186,000 mi/sec).
A nanometer equals one billionth (10^-9) of a meter or ten Ångstroms (Å), a unit often used to specify the size of wavelengths. (For example, 400 nm = 4000 Å.)
Frequency equals the number of waves passing per second (frequency and wavelength are inversely related); historically the unit of frequency was the cycle (wave) per second now called a hertz (Hz). MHz = 1 million Hz.
Visible (light) is often called the visible or optical window because light easily passes through air (see last column of table).
Notice the range of visible wavelengths is about a factor of two (from just under 400 nm for violet to just over 700 nm for red).
Indigo is often grouped with violet and blue.
Microwaves are often grouped with long infrared waves and short radio waves.
Radio is often called the radio window because radio easily passes through air (see last column of table).

Table 8. The Electromagnetic Spectrum
Designation⁽¹⁾	Wavelength (nanometers)⁽²⁾	Frequency⁽³⁾ (lower limit)	Photon Energy	Atmospheric Transparency
Gamma Rays	< 0.1 nm (Very Small)	(Enormous)	(Enormous)	Very Poor
X Rays	0.1-10 nm	Very Poor
Ultraviolet	10-380 nm	Poor
Visible (Light)⁽⁴⁾	380-750 nm ⁽⁵⁾	Excellent
Violet	380-420 nm (Violet Wavelengths About 1/2 Red Wavelengths)
Indigo⁽⁶⁾	420-450 nm
Blue	450-490 nm
Green	490-570 nm
Yellow	570-590 nm
Orange	590-630 nm
Red	630-750 nm (Red Wavelengths About 2 times Violet Wavelengths)
Infrared	750 nm-0.1 mm	Poor
Microwave⁽⁷⁾	0.1 mm-10 cm	Fair to Good
Radio⁽⁸⁾	over 10 cm (Very Large)	(Small) (less than 3,000 MHz)	(Very Small)	Very Good
FM Radio	2.8-3.4 m	108-88 MHz		(Poor over 10 m)
AM Radio	190-560 m	1,600-540 MHz

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