Television picture

The largest use for barium is as a getter to remove the last traces of gases from vacuum and television picture tubes. It is ideal for this use because of its combination of high chemical reactivity and low vapor pressure (28—32). In some cases it is used as powder obtained by vaporization ia an electric arc (33). It can also be used as an aluminum ahoy (see Vacuum technology). 

Fem aufnabme, /. telephotography. >bild, n. telephotograph television picture. 

Tantalum, oxidation number, 414 "Teflon, 347 Tehachapi mountains, 132 Tejon pass, 132 Television picture tube, 409 Temperature absolute, 57 absolute zero, 58 earth s center, 440 effect on equilibrium, 67, 148,167 on gas volume, 57 on rate, /29 on K,r, 181... 

A television picture tube is a form of cathode-ray tube (Section 1.1) in which the beam of electrons is directed toward a screen that emits light where they strike it. Have you ever wondered what the pressure is inside the tube Estimate the pressure (in atmospheres), given that the volume of the tube is 5.0 L, its temperature is 23°C, and it contains 0.010 mg of nitrogen gas. 

Medical scanners have an array of transducers in each probe and are capable of providing thousands of measurements of the small changes in the velocity of sound as it passes through various phase changes within the body. This information is fed to computers that create a television picture of the internal tissues of the human body. 

Uses. Coating screens of television picture tubes mold binders corrosion-resistant coatings catalyst preparation silicone intermediate... 

The most important use of barium is as a scavenger in electronic tubes. The metal, often in powder form or as an alloy with aluminum, is employed to remove the last traces of gases from vacuum and television picture tubes. Alloys of barium have numerous applications. It is incorporated to lead alloy grids of acid batteries for better performance and added to molten steel and metals in deoxidizing alloys to lower the oxygen content. Thin films of barium are used as lubricant suitable at high temperatures on the rotors of anodes in vacuum X-ray tubes and on alloys used for spark plugs. A few radioactive isotopes of this element find applications in nuclear reactions and spectrometry. 

Phosphors are solids which absorb energy and re-emit it as light. As in the lasers we have just described, the emitter is usually an impurity ion in a host lattice. However, for the uses to which phosphors are put it is not necessary to produce intense, coherent beams of light, and the emitting process is spontaneous instead of induced. Phosphors have many applications, for example, the colours of your television picture are produced by phosphors that are bombarded with electrons from a beam (cathode rays) or from a transistor (flat screen LCD displays). In terms of tonnage produced, one of the most important applications is the fluorescent light tube. 

Tungsten chemicals find limited use in inks, paints, enamels, dyes, and glass manufacture. Some tungsten compounds and their derivative phosphors find use in x-ray screens, television picture tubes, and luminescent light sources. 

A television picture tube is a form of cathode ray tube in which the beam of j electrons is directed toward colored phosphors on the screen. A very low pressure is required to minimize the collisions between the electrons in the = beam and the gas molecules. Collisions and the resulting deflections of the j electrons would give a blurred, dim picture. 

The simplest case is the reconstruction of two-dimensional structures from one-dimensional projections. A digitised two-dimensional structure, for example a television picture, can be described as an n n matrix [f ] of side D and cells (ij) of side d = D/n (Figure 3.4). A projection of the picture at an angle if is a set of parallel rays (if,A) which totally cover the picture at the angle if, and any projection ray can be represented by an n-n matrix (Figure 3.5) where each element a A is the fraction of the cell (/,/) which is contained within the ray (if,A). The picture matrix and the ray-matrices are easily transformed into vectors (Figure 3.6). More precisely, the picture matrix [L] is replaced by a column-vector [A, and the ray matrices [a A ] are described by row-vectors [a ] with the transformations ... 

Luminescent Pigments. This group of pigments covers a number of technologies and markets ranging from color television picture tubes to glow-in-the-dark ... 

Figure 3 shows the SPD of the old (A) and new (B) cool-white lamps. The new triphosphor lamp, based on phosphors developed for television picture tubes is much better at rendering color than the old monofluorophosphor (12). From their SPDs, one could hardly call them equivalent. They do however meet the criteria of color rendition, to "fool the eye", very well. 

This interaction of electrons with a magnetic field could cause a television picture to distort in the presence of a magnet. The electron beam in the cathode ray tube (CRT or television tube), which causes the phosphorescence on the screen, bends in a magnetic field. Of course, one should not bring a magnet up to a TV screen unless one has a dispensable TV because the interaction could do permanent damage to the electronics. But if one has a dispensable TV, it is an interesting effect to witness. 

Dealing with various sizes and orientations of boxes is more difficult. Our fourth-generation crane used a television camera above the input conveyor belt, coupled to an analysis program that found the edges and shape, such that it could recognize a box, its orientation, and its location. To do this, it had to consult an internal memory that defined what a box looked like in a television picture. 

Determine the pressnre inside a television picture tube with a volume of 3.50 L that contains 2.00 X 10 g of nitrogen gas at 22.0°C. 

The name comes from the town of Strontian in Scotland and was given to the element by Thomas Hope (1766-1844). There are many claims for the original discovery of strontium. William Cruikshank, in 1787, and Adair Crawford, in 1790, both examined strontianite (SrC03) and recognized that it had unique properties. Thomas Hope noted an unknown earth in 1791. Martin Klaproth presented a paper on a number of strontium compounds in 1793 and 1794. Richard Kirwan (1733-1812) examined a number of strontium compounds and presented his findings in 1794. It was Davy who isolated strontium metal, in 1808. Strontium does not occur in pure form in nature but is found in small quantities in many places. Some forms of strontium are radioactive, particularly 90Sr, which has been found in nuclear fallout. It can also be used in SNAP devices (Systems for Nuclear Auxiliary Power) as a power source. The main commercial use of strontium is in the glass of color television picture tubes. 

Heating coils or boats for vacuum metallizing (W and NS-W). Tungsten is an excellent material for evaporation sources. Coils (Fig. 7.13) and boats (Fig. 7.14) of different size and shape are used. The main application is to evaporate aluminum, but a variety of other metals and metal compounds can be evaporated too, as listed in Table 7.2. Evaporization is performed for metallizing different products such as reflector lamps, head lamps, television picture tubes, electronic components, plastic, etc. 

A combination of the oxides of yttrium (Y), a transition element, and europium (Eu) produce a phosphor that glows a brilliant red when struck by a beam of electrons, such as in a TV picture tube. This phosphor is used with blue and green phosphors to produce realistic-looking television pictures. When rare earth phosphors are used in mercury-arc outdoor lighting, they change the bluish light of the mercury arc to a clear white light. 

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