X RAY

The relationship of X rays to other electromagnetic radiation within the electromagnetic spectrum. any electromagnetic radiation of an extremely short wavelength produced by the deceleration of charged particles or the transitions of electrons in atoms. As can be seen in the Figure, the wavelengths of X rays range from about 10-8 metres to 12-12 metres, with corresponding frequencies of 1016 to 1021 hertz (Hz). Like other forms of electromagnetic radiation (gamma rays, ultraviolet, visible light, infrared, and radio waves), X rays have the same speed in vacuo (c, equal to 3 1010 centimetres per second [about 186,000 miles per second]) and show phenomena associated with its wavelike nature, such as interference, diffraction, and polarization. X rays were discovered in Wrzburg, Ger., on Nov. 8, 1895, by Wilhelm Conrad Rntgen. Rntgen made his discovery while investigating the effects of cathode rays that were produced by electrical discharges through gases at low pressures (cathode rays are electrons that are emitted from the negative electrode, or cathode, of the discharge tube). Although many scientists had studied the properties of cathode rays, Rntgen discovered an effect that had escaped these earlier investigatorsnamely, that a surface coated with barium platinocyanide placed outside a discharge tube would emit light (fluoresce) even when it was shielded from the direct visible and ultraviolet light of the gaseous discharge. He deduced that an invisible radiation from the tube passed through the air and fluoresced the screen. He named these strange new rays X rays to indicate their unknown nature.