X Ray (Encyclopedia of Science)
X rays are a form of electromagnetic radiation with wavelengths that range from about 10 to about 105 meter. No sharp boundary exists between X rays and ultraviolet radiation on the longer wavelength side of this range. Similarly, on the shorter wavelength side, X rays blend into that portion of the electromagnetic spectrum called gamma rays, which have even shorter wavelengths.
X rays have wavelengths much shorter than visible light. (Wave lengths of visible light range from about 3.5 10 meter to 7.5 10 meter.) They also behave quite differently. They are invisible, are able to penetrate substantial thicknesses of matter, and can ionize matter (meaning that electrons that normally occur in an atom are stripped away from that atom). Since their discovery in 1895, X rays have become an extremely important tool in the physical and biological sciences and the fields of medicine and engineering.
X rays were discovered in 1895 by German physicist William Roentgen (1845923) quite by accident. Roentgen was studying the conduction of electricity through gases at low pressure when he observed that a fluorescent screen a few meters from his experiment suddenly started to glow. Roentgen concluded that the glow was caused by certain unknown rays that were given off in his experiment. Because of its unknown character, he called this...
(The entire section is 1396 words.)
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