Elements of natural philosophy (Volume 2-3) . rfaceand the nature of the two media on the opposite sides ofthe latter being given, the value of/*, I7 and V will beknown; and assuming the direction of the incident rayD C, the angle 9 also becomes known, and the value off\ which determines the point II, will result fromEquation (32), and the direction of the refracted rayHOG, will thence become known. For the reflected ray, V and V become equal withcontrary signs, and m will be equal to minus unity. Thiswill reduce Equation (32) to that is to say, all the reflected rays will diverge froma point
Elements of natural philosophy (Volume 2-3) . rfaceand the nature of the two media on the opposite sides ofthe latter being given, the value of/*, I7 and V will beknown; and assuming the direction of the incident rayD C, the angle 9 also becomes known, and the value off\ which determines the point II, will result fromEquation (32), and the direction of the refracted rayHOG, will thence become known. For the reflected ray, V and V become equal withcontrary signs, and m will be equal to minus unity. Thiswill reduce Equation (32) to that is to say, all the reflected rays will diverge froma point D\ as far behind the deviating surface as thepoint D of disturbance is in front of it. The reflectedpulse will, therefore, be spherical. From the point D as a centreand radius D K, equal to thatof the spherical pulse at anyinstant, describe the arc 0 KOr;this will represent a section ofthe incident pulse by a planenormal to the deviating the distance ED equalto D E, and with Dr as a centre,and radius Df K{ equal to D K, Fis. ELEMENTS OF ACOUSTICS. 87 describe the arc 0 K 0; this will represent a section, construction ofby the same plane, of the reflected pulse. Draw any ^rnact^an^incident ray as D C; through the point H, given by the reflected of f in Equation (32), and the point (7, draw H C,which being produced will give the refracted ray G X\through Df draw the line Df C X, and multiply the inter-cepted portion CX by the ratio of the velocities V and F,and lay off the product from C to X\ and we have thepoint X of the refracted, corresponding to the point Xof the reflected pulse. An ear situated at X will hearthe direct sound transmitted along the ray D JT, and an Position whenceecho of the same sound reflected at the point G\ thethedirectsound and the echo are interval of time, or number of seconds intervening be-both audible;tween the two, being equal to DG +GX-DX Time between 1089,42 V 1+ ^o _ 320) m 0,00208 the impressions; on the suppositi
Size: 1659px × 1506px
Photo credit: © The Reading Room / Alamy / Afripics
License: Licensed
Model Released: No
Keywords: ., bookcentury1800, booksubjectmechanics, booksubjectopticsandphoto
