. A text book of physics, for the use of students of science and engineering . n with centresequally spaced round a small circle 123, etc. (Fig. 633). A strip ofcardboard or metal has a rectangular slot cut in it and is placedwith the slot over the circles so that small parts ABC, etc., of thecircles can be seen. On rotating the large circles about the centreO, each small part ABC, etc., moves backwards and forwards alongthe slot over a path equal to the diameter of the circle 123, etc. LIV LONGITUDINAL WAVES 685 Compression and rarefaction waves will then be seen to travelsuccessively along t
. A text book of physics, for the use of students of science and engineering . n with centresequally spaced round a small circle 123, etc. (Fig. 633). A strip ofcardboard or metal has a rectangular slot cut in it and is placedwith the slot over the circles so that small parts ABC, etc., of thecircles can be seen. On rotating the large circles about the centreO, each small part ABC, etc., moves backwards and forwards alongthe slot over a path equal to the diameter of the circle 123, etc. LIV LONGITUDINAL WAVES 685 Compression and rarefaction waves will then be seen to travelsuccessively along the slot. Representation of a longitudinal wave by a sine curve.—Since theparticles of the medium move in the direction of propagation of thewave, it follows that in the case of a longitudinal wave, particlesoriginally in a straight line in the direction of the wave remain inthat straight line. This row of particles will never take the shape ofa sine curve, as do the particles in the case of a transverse wave(Fig. 625). The correct representation of the wave must therefore. Fig. 634.—Displacement curve for longitudinal wave. be by means of a row of strokes or dots as in Fig. 632. Never-theless the wave may be represented diagrammatically to scale bymeans of a sine curve in the following manner : If ABC ... EFG (Fig. 634), are the undisturbed positions of certainparticles, then at a given instant during the passage of the wave,their positions may be B, C, ... etc. ... EF. If we make B&=BB,Cc=CC, etc., and F/=FF, measuring a displacement to the righthand upwards, and to the left hand downwards, the curve Abed ...etc. ... efg is obtained, in which the ordinates represent the displace-ments of the particles. Such a curve is called a, displacement curvefor the wave,.. in displacement of the particles may_befound by moving such a curve with the velocity of propagation ofthe wave, as on p. 681. Owing to the usual smallness of the displacements in the case ofan actua
Size: 2030px × 1231px
Photo credit: © Reading Room 2020 / Alamy / Afripics
License: Licensed
Model Released: No
Keywords: ., bookcentury1900, bookdecade1910, bookpublishe, booksubjectphysics
