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:
“One is not idle because one is absorbed. There is both visible and invisible labor. To contemplate is to toil, to think is to do. The crossed arms work, the clasped hands act. The eyes upturned to Heaven are an act of creation.”
—Victor Hugo (1802–1885)
“Spades take up leaves
No better than spoons,
And bags full of leaves
Are light as balloons.”
—Robert Frost (1874–1963)
“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)