Visible Light Beams
From the side, a beam of light is only visible if part of the light is scattered by objects: tiny particles like dust, water droplets (mist, fog, rain), hail, snow, or smoke, or larger objects such as birds. If there are many objects in the light path, then it appears as a continuous beam, but if there are only a few objects, then the light is visible as a few individual bright points. In any case, this scattering of light from a beam, and the resultant visibility of a light beam from the side, is known as the Tyndall effect.
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Famous quotes containing the words visible, light and/or beams:
“Being a parent is unlike any previous job—the results of any one action are not clearly visible for a long time, if at all.”
—Anonymous Mother. As quoted in Between Generations by Ellen Galinsky, ch. 2 (1981)
“Signal smokes, war drums, feathered bonnets against the western sky. New messiahs, young leaders are ready to hurl the finest light cavalry in the world against Fort Stark. In the Kiowa village, the beat of drums echoes in the pulsebeat of the young braves. Fighters under a common banner, old quarrels forgotten, Comanche rides with Arapaho, Apache with Cheyenne. All chant of war. War to drive the white man forever from the red man’s hunting ground.”
—Frank S. Nugent (1908–1965)
“The highway presents an interesting study of American roadside advertising. There are signs that turn like windmills; startling signs that resemble crashed airplanes; signs with glass lettering which blaze forth at night when automobile headlight beams strike them; flashing neon signs; signs painted with professional touch; signs crudely lettered and misspelled.... They extol the virtues of ice creams, shoe creams, cold creams;...”
—For the State of Florida, U.S. public relief program (1935-1943)