Elementary natural philosophy : designed for high schools and academies (1881)
Griffin, La Roy F. (La Roy Freese), 1844-1916 · Philadelphia : Sower, Potts & Co. · leaf 121
n be readily shown experi-mentallv by means of the Hopkins tube, Fig. 137.This consists of an open tube with two branches,and is suspended over a vibrating glass plate. Thewaves from one side interfere with those fromthe other and produce silence to an ear placedabove the tube. 389. Beats. If the… … Fig. 137. 390. Beats may be shown experimentally by placing a bit ofwax upon one prong of a tuning fork which vibrates in unison,that is at the same rate, with a second.* The load causes the forkto vibrate a little slower, and produces beats. 391. Echo. An echo is sound reflected from an objectat…
Physics
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