Word: ultraviolet
(lookup in dictionary)
(lookup stats)
Dates: all
Sort By: most recent first
(reverse)
First noticed last October among welders at Portland, the affliction appeared to be nothing more than an outbreak of usual welders' eye injuries, caused by ultraviolet rays of torches, or specks of emery dust and steel splinters that lodged in the eyes. But when a large number of California welders had applied for State compensation, authorities realized they were dealing with an epidemic, not an occupational injury...
...glow only after stimulation by light. If the pigment glows for several minutes or hours after exposure to light, it is phosphorescent. If the afterglow is very brief-perhaps only 1/10,000th of a second - the pigment is fluorescent. Hence fluorescent substances glow only when continuously exposed to invisible ultraviolet rays ("black light"), which they reflect as visible light...
...Ultraviolet photography is revealing so many more nebulae near the uttermost range of the telescope that astronomers may have to reconsider their theories as to the size of the star-filled universe. Ordinary photographs showed fewer & fewer nebulae out near the 500,000,000 light-year limit of range, and some scientists assumed that this might be the approximate radius beyond which lay infinite emptiness. But Astronomers Albert Edward Whitford and Joel Stebbins of the University of Wisconsin knew that the far-off nebulae were reddish (a spectroscopic phenomenon which makes many astronomers believe outer galaxies are moving away from...
...powerful electric current-i.e., a stream of electrons -jumps through a vacuum tube and hits a "target,", usually a piece of tungsten. The electrons batter from the tungsten a secondary stream of chargeless particles, X-rays, whose wave lengths are thousands of times shorter than those of ultraviolet light and almost as short as those of radium's gamma rays. The shorter waves are the farther they penetrate into matter before their energy is dispersed. The stronger the voltage the shorter the resulting X-ray wave length and the greater the penetration. Thick Navy steels can be radiographed...
...gloom of dark cinema houses, people are likely to stumble, bump into others. Ushers with flashlights are nuisances; small lamps placed near the aisle floors illuminate only small areas. American Cyanamid Co. announced what it considers a better idea: aisle rugs treated with fluorescent dyes, bathed by invisible ultraviolet radiation from small tubes. Such rugs glow softly all over, interfere with nothing on the screen. General Electric's House of Magic at the New York World's Fair has a fluorescent aisle...