Rays X

X rays are electromagnetic waves with wavelengths covering a fairly broad range from about 3 × 10^-8 ft (10^-8 m) to 3 × 10^-11 ft (10^-11 m). There is no sharp boundary between x rays and ultraviolet light on the long wavelength side of this range. Similarly, on the short 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, which occurs between 1.2 × 10^-6 and 2.1 × 10^-6 ft (4 × 10^-7 and 7 × 10^-7 m), and they also behave quite differently. They are invisible, are able to penetrate substantial thicknesses of matter, and can ionize matter. Since the time of their discovery in 1895 they have been an extremely important tool in the physical and biological sciences and the fields of medicine and engineering.