. Light, a textbook for students who have had one year of physics. Figure 18 and cosine forms, of different wavelengths. For this are compelled to make a special study of waves of thesesimple forms. FORMULA FOR A WAVE 39. Figure 19 21. Mathematical formula for a wave.—In figure 19; Arepresents a sine-curve, whose equation is y = 2ttX a B a cosine-curve, whose equation is 2ttX v = — (1) (2) and C a third curve whose equation is y = — (x —a a) (3) Evidently, all three are exactly the same in form, and eithercan he transformed into one of the others by shifting it alo
. Light, a textbook for students who have had one year of physics. Figure 18 and cosine forms, of different wavelengths. For this are compelled to make a special study of waves of thesesimple forms. FORMULA FOR A WAVE 39. Figure 19 21. Mathematical formula for a wave.—In figure 19; Arepresents a sine-curve, whose equation is y = 2ttX a B a cosine-curve, whose equation is 2ttX v = — (1) (2) and C a third curve whose equation is y = — (x —a a) (3) Evidently, all three are exactly the same in form, and eithercan he transformed into one of the others by shifting it alongthe axis of x. In fact, we can represent either of the threecurves by the formula (3) provided a is given a suitable value,different in each case. If a = 0, we have the simple cosinecurve. If a — a/4 we have y = *. (x -») = (55 - |) „ . 2ttX —a the equation of the sine curve. Whatever value a may have,its presence indicates that equation (3) represents a simplecosine curve shifted in the positive direction of x by the dis-tance a. For y has the same value for x in (3) that it hasfor x — a in (2). Equations (1), (2), and (3) do not represent waves, butonly stationary curves. For such a cu
Size: 2611px × 957px
Photo credit: © The Reading Room / Alamy / Afripics
License: Licensed
Model Released: No
Keywords: ., bookcentury1900, bookdecade1920, booksubjectlight, bookyear1921
