. The Ontario high school physics. are flattened into ellipses with the long axeshorizontal. 162 WAVE MOTION Also, the oscillatory motion of the particles rapidly diminisheswith the depth. At the depth of a wave-length it is less than s^jsof that at the surface. At a few hundred feet down—a distancesmall compared with the depth of the ocean—the water is quite still,even though the surface may be in very violent motion under fearfulstorms. A submarine boat, by descending a hundred feet, couldpass from the midst of a terrific tempest to a region of perfect quiet. 183. Refraction of Water Waves.
. The Ontario high school physics. are flattened into ellipses with the long axeshorizontal. 162 WAVE MOTION Also, the oscillatory motion of the particles rapidly diminisheswith the depth. At the depth of a wave-length it is less than s^jsof that at the surface. At a few hundred feet down—a distancesmall compared with the depth of the ocean—the water is quite still,even though the surface may be in very violent motion under fearfulstorms. A submarine boat, by descending a hundred feet, couldpass from the midst of a terrific tempest to a region of perfect quiet. 183. Refraction of Water Waves. It has often beenobserved that when waves approach a shallow beach the crests „:■.--■-::::;■ are usually approxi- mately parallel to theshore line. In Fig. 193,A,B,G, etc., represent thesuccessive positions of awave approaching theshore. The dotted linesindicate the depth ofwater. It is seen that theend of the wave nearestthe shore reaches shallowwater first, and at oncetravels more continues until at. 12 4 6 8 10inches deep Fig. 193.—Diagram illustrating how a wave changes its last the Wave is alniOStdirection of motion as it gets into shallower water, n i . .1 i t and is refracted. parallel to tlie shore line. This changing of the direction of the motion of the wavesthrougli a change in their velocity is called refraction. 184. Reflection of Waves. If, however, a train of waterwaves strike a precipitous shore or ^~^, \^C >S< r B a long pier, they do not stop there, but start off again in a definite direction. This is illustrated in Fig. 194. The waves advance along AB, strike the pier and are reflected in tlie direction BG, the lines AB, BG making equal angles with BD the perpendicular to the pier. In sound and light we meet with many illustrations of reflection and refraction. Fio. 194.—Water waves striking a longpier are reflected. STUDY OF WAVES IN A CORD 1C3 185. Study of Waves in a Cord, Let one end of a lightchain or rubljor tube,
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Keywords: ., bookcentury1900, bookdecade1910, bookpublishe, booksubjectphysics
