Callan,+J.+J.

Callan, J. J. (1980). //Radiography In Modern Industry//. Retrieved January 1, 2010, from Kodak: [] -”X-rays are a form of electromagnetic radiation (EMR), as is light.” -“Their distinguishing feature is their extremely short wavelength--only about 1/10,000 that of light, or even less.” -“This characteristic is responsible for the ability of x-rays to penetrate materials that absorb or reflect ordinary light.” -“X-rays exhibit all the properties of light, but in such a different degree as to modify greatly their practical behavior.” -“For example, light is refracted by glass and, consequently, is capable of being focused by a lens in such instruments as cameras, microscopes, telescopes, and spectacles.” - “Xrays are also refracted, but to such a very slight degree that the most refined experiments are required to detect this phenomenon.”  - “Hence, it is impractical to focus x-rays.”  - “It would be possible to illustrate the other similarities between x-rays and light but, for the most part, the effects produced are so different--particularly their penetration--that it is preferable to consider x-rays andgamma rays separately from other radiations.” -“A radiograph is a photographic record produced by the passage of x-rays or gamma rays through an object onto a film.” -“See the figure below. When film is exposed to x-rays, gamma rays, or light, an invisible change called a latent image is produced in the film emulsion.” -“The areas so exposed become dark when the film is immersed in a developing solution, the degree of darkening depending on the amount of exposure.” - “After development, the film is rinsed, preferably in a special bath, to stop development.” -“The film is next put into a fixing bath, which dissolves the undarkened portions of the sensitive salt.” -“It is then washed to remove the fixer and dried so that it may be handled, interpreted, and filed.” -“The developing, fixing, and washing of the exposed film may be done either manually or in automated processing equipment.” -“X-rays are produced when electrons, traveling at high speed, collide with matter or change direction.” -“In the usual type of x-ray tube, an incandescent filament supplies the electrons and thus forms the cathode, or negative electrode, of the tube.” - “A high voltage applied to the tube drives the electrons to the anode, or target.” -“The sudden stopping of these rapidly moving electrons in the surface of the target results in the generation of x-radiation.” -“The design and spacing of the electrodes and the degree of vacuum are such that no flow of electrical charge between cathode and anode is possible until the filament is heated.”