A text-book on chemistryFor the use of schools and colleges . nger wavesgive rise to red light, the shorter ones to violet, andthose of intermediate magnitudes, the other colors inthe ord^r of their refrangibility. Two rays of light, no matter how brilliant they areseparately, may be brought under such relations to oneanother as to destroy each others effect and producedarkness; two sounds may bear such a relation to eachother that they shall produce silence; and two waves onthe surface of water may so interfere with one anotherthat the water shall retain its horizontal position. Take two tuni
A text-book on chemistryFor the use of schools and colleges . nger wavesgive rise to red light, the shorter ones to violet, andthose of intermediate magnitudes, the other colors inthe ord^r of their refrangibility. Two rays of light, no matter how brilliant they areseparately, may be brought under such relations to oneanother as to destroy each others effect and producedarkness; two sounds may bear such a relation to eachother that they shall produce silence; and two waves onthe surface of water may so interfere with one anotherthat the water shall retain its horizontal position. Take two tuning-forks of the same note,and fasten by a little sealing-wax on oneprong of each a disc of cardboard half aninch in diameter, as seen in Fig. 78, a. Makeone of the forks a little heavier than the oth-er by putting on the end of it a drop of thewax. Then take a glass jar, 5, about two inchesin diameter and eight or ten long, and hav- What is meant by wave length ? What effect has the length ofundulation on the color of light ? Describe the experiment Fig. 78. 104 TWO SOUNDS PRODUCE SILENCE. ing made one of the forks vibrate, hold it over themouth of the jar, as seen at c?, its piece of cardboard be-ing downward; commence pouring water into the jar,and the sound will be greatly re-enforced. It is the col-umn of air in the jar vibrating in unison with the fork,and we adjust its length by pouring in the the sound is loudest we cease to pour in anymore water, the jar is adjusted, and we can now provethat two sounds added together may produce silence. It matters not which fork is taken, whether it be thelight or the loaded, on making it vibrate and holding itover the mouth of the resonant jar, we hear a uniformand clear sound, without any pause, stop, or if we make both vibrate over the jar together, a re-markable phenomenon arises—a series of sounds alter-nating with a series of silences; for a moment the soundincreases, then dies away and ceases, then swe
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