Electromagnetic+Spectrum


 * The //electromagnetic spectrum// is the distribution of electromagnetic radiation according to energy (or equivalently, by virtue of the relations in the previous section, according to frequency or wavelength).**

**Regions of the Electromagnetic Spectrum**

 * The following table gives approximate wavelengths, frequencies, and energies for selected regions of the electromagnetic spectrum.****
 * ~ Spectrum of Electromagnetic Radiation ||
 * **Region** || **Wavelength**
 * (Angstroms)** || **Wavelength**
 * (centimeters)** || **Frequency**
 * (Hz)** || **Energy**
 * (eV)** ||
 * Radio || > 109 || > 10 || < 3 x 109 || < 10-5 ||
 * Microwave || 109 - 106 || 10 - 0.01 || 3 x 109 - 3 x 1012 || 10-5 - 0.01 ||
 * Infrared || 106 - 7000 || 0.01 - 7 x 10-5 || 3 x 1012 - 4.3 x 1014 || 0.01 - 2 ||
 * Visible || 7000 - 4000 || 7 x 10-5 - 4 x 10-5 || 4.3 x 1014 - 7.5 x 1014 || 2 - 3 ||
 * Ultraviolet || 4000 - 10 || 4 x 10-5 - 10-7 || 7.5 x 1014 - 3 x 1017 || 3 - 103 ||
 * X-Rays || 10 - 0.1 || 10-7 - 10-9 || 3 x 1017 - 3 x 1019 || 103 - 105 ||
 * Gamma Rays || < 0.1 || < 10-9 || > 3 x 1019 || > 105 ||


 * The notation "eV" stands for electron-volts, a common unit of energy measure in atomic physics. A graphical representation of the electromagnetic spectrum is shown in the figure below.**
 * [[image:http://csep10.phys.utk.edu/astr162/lect/light/EMspectrum.gif width="580" height="185" align="center"]] ||
 * ** The electromagnetic spectrum  ** ||


 * Thus we see that visible light and gamma rays and microwaves are really the same things. They are all electromagnetic radiation; they just differ in their wavelengths.**

**The Spectrum of Visible Light**

 * The visible part of the spectrum may be further subdivided according to color, with red at the long wavelength end and violet at the short wavelength end, as illustrated (schematically) in the following figure.****
 * [[image:http://csep10.phys.utk.edu/astr162/lect/light/roygbv.gif width="450" height="165" align="center"]] ||
 * ** The visible spectrum  ** ||