X-Rays:
The x-ray spectrum contains EM energy at wavelengths from around 1 nm down to 0.01 nm. (Different sources conflict somewhat on the separating line among the hard-UV and x-ray areas.) Proportionately, the x-ray spectrum is big as compared with the visible range.
The X-rays were discovered by mistake in 1895 by a physicist named Wilhelm Roentgen during experiments including electric currents in gases at low pressure. When the current was adequately intense, the high-speed electrons generated mysterious radiation whenever they struck the anode (i.e., positively charged electrode) in the tube. The rays were termed as x-rays since of their behavior, never before observed. The rays were capable to penetrate barriers opaque to visible light and UV. The phosphor-coated object occurred to be in the vicinity of the tube having the gas, and Roentgen observed that the phosphor glowed. Consequent experiments showed that the rays possessed too much penetrating power that they passed via the skin and muscles in the human hand, cast shadows of bones on a phosphor-coated surface. The Photographic film could be exposed in the similar way.
Modern x-ray tubes execute by accelerating electrons to very high speed and forcing them to hit a heavy metal anode (generally made of tungsten). The simplified functional diagram of an x-ray tube of the kind used by dentists to position cavities in your teeth is shown in figure below.
Figure: Functional diagram of an x-ray tube.
Since the wavelengths of x-rays become shorter and shorter, it becomes rising hard to direct and focus them. This is so as of the penetrating power of the short-wavelength rays. The piece of paper with a minute hole works very well for UV photography; in the x-ray spectrum, the radiation passes right via the paper. Even aluminum foil is associatively transparent to x-rays. Though, when x-rays land on a reflecting surface at a nearly grazing angle, and when the reflecting surface is made up of appropriate material, a few degree of focusing can be realized. The minimum the wavelength of the x-rays, the minor the angle of incidence, measured associative to the surface, should be if reflection is to occur. At the shortest x-ray wavelengths, the angle should be smaller than 1° of arc. Such grazing reflection effect is shown in figure below. A rough example of how a high-resolution x-ray observing device attains its focusing is shown in figure below in part (b). The focusing mirror is tapered in the shape of an extended paraboloid. Since parallel x-rays enter the aperture of the reflector, they strike its internal surface at a grazing angle. The x-rays are fetched to a focal point, wherever a radiation counter and detector can be positioned.
Figure: (a) x-rays are reflected from a surface only whenever they strike at a grazing angle. (b) The functional diagram of an x-ray focusing and observing device.
The X-rays cause ionization of the living tissue. This effect is cumulative and can outcome in injure to cells over a era of years. This is why x-ray technicians in doctors' and dentists' offices work at the back a barrier lined with lead. Or else, these personnel would be subjected to hazardous cumulative doses of x radiation. It only receives a few millimeters of lead to block virtually nearly all x-rays. Less dense metals and other solids can also block x-rays, though these should be thicker. The significant factor is the quantity of mass via which the radiation should pass. Sheer physical displacement can also decrease the intensity of x radiation, which reduces according to the square of the distance. Though, it isn't practical for most of the doctors or dentists to work in offices large sufficient to make this a viable alternative.