Unit of x-radiation or gamma radiation
Or röntgen; Unit (symbol r) of radiation exposure, used for X-rays and gamma rays. It is defined in terms of the number of ions produced in one cubic centimeter of air by the radiation. Exposure to 1,000 roentgens gives rise to an absorbed dose of about 870 rads (8.7 grays), which is a dose equivalent of 870 rems (8.7 sieverts).
A unit of gamma radiation measured by the amount of ionization in air. In non-bony biological tissue 1 roentgen delivers a dose approximately equal to 1 rad.
A unit of radiation exposure; the dose of ionizing radiation that will produce 1 electrostatic unit of electricity in 1 cc of dry air; SYN. r.
See röntgen. + prikaži više

Electromagnetic radiation of short wavelength produced when high-speed electrons strike a solid target; Also called: X-radiation, roentgen ray.
Band of electromagnetic radiation in the wavelength range 10-11 to 10-9 m (between gamma rays and ultraviolet radiation; see electromagnetic waves). Applications of X-rays make use of their short wavelength (as in X-ray diffraction) or their penetrating power (as in medical X-rays of internal body tissues). X-rays are dangerous and can cause cancer.
X-rays with short wavelengths pass through most body tissues, although dense areas such as bone prevent their passage, showing up as white areas on X-ray photographs. The X-rays used in radiotherapy have very short wavelengths that penetrate tissues deeply and destroy them.
X-rays were discovered by German experimental physicist Wilhelm Röntgen in 1895 and formerly called roentgen rays. They are produced when high-energy electrons from a heated filament cathode strike the surface of a target (usually made of tungsten) on the face of a massive heat-conducting anode, between which a high alternating voltage (about 100 kV) is applied. + prikaži više

(or Roentgen) (1845-1923) German physicist who discovered X-rays 1895. While investigating the passage of electricity through gases, he noticed the fluorescence of a barium platinocyanide screen. This radiation passed through some substances opaque to light, and affected photographic plates. Developments from this discovery revolutionized medical diagnosis. Nobel Prize 1901.
The unit of radiation exposure (X-ray) is named roentgen or röntgen (R) after him.
Röntgen was born in Lennep, Prussia, and studied in Switzerland at the Zürich Polytechnic. He was professor at Giessen 1879–88, then director of the Physical Institute at Würzburg, and ended his career in the equivalent position at Munich 1900–20.
It was at Würzburg Röntgen conducted the experiments that resulted in the discovery of the rays formerly named for him; they are now called X-rays. Today, the unit of radiation exposure is called the roentgen, or röntgen (symbol R). He refused to make any financial gain out of his findings, believing that the products of scientific research should be made freely available to all.
Röntgen worked on such diverse topics as elasticity, heat conduction in crystals, specific heat capacities of gases, and the rotation of plane-polarized light. In 1888 he made an important contribution to electricity when he confirmed that magnetic effects are produced by the motion of electrostatic charges. + prikaži više