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[[File:EM Spectrum Properties edit.svg|thumb|right|200px|Spectrum properties of electromagnetic radiation are diagrammed. Credit: .]]
'''Electromagnetic radiation''' comes in many different types, although the differences between them are quantitative rather than qualitative.  This teaching aid lists the different types that are generally recognised.

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It follows that a photon with an energy of 1eV has a frequency of 1 eV/h = 2.41799 x 10<sup>14</sup> Hz or about 242 THz and a wavelength of c.h/1 eV = 1.23984 x 10<sup>-6</sup> m or about 1,240nm or 12,400Å.  As will be seen below, that would put the photon in the infrared range.  In practice, photon energies are never quoted for such long wavelengths.

'''Exercise:''' Find why photon energies are only important at very short wavelengths.

==
Frequency Bands==
{{main|Radiation astronomy/Bands|Band astronomy}}
The electromagnetic spectrum is divided into several bands.  These definitions are generally informal and vague, and the bands may overlap.  There seems to be a gap between the ultra-violet and X-ray bands.  Sometimes, the choice of band depends on how the radiation is generated.  For example, radiation from radioactive decay is always referred to as gamma rays, even if its photon energy would class it as X-rays.

The main bands used, in order of decreasing wavelength (hence increasing frequency and photon energy) are:

* [[Radio]]
* [[Microwaves]]
* [[Infra-Red]]
* [[Visible light]]
* [[Ultra-violet]]
* [[X-rays]]
* [[Gamma rays]]

A convenient mnemonic for remembering these is "'''R'''abbits '''M'''ate  '''I'''n '''V'''ery '''U'''nusual e'''X'''pensive '''G'''ardens".

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== See also ==
* [[Electromagnetic fields and waves]]

==External links==
[[Category:Physics]]
[[Category:Radiation]]
[[Category:Resources last modified in August 2016]]