# Chapter 19 - Think and Rank: 42

a. D, B, A = C b. D, A, B, C c. C, B, A, D d. D, A, B, C

#### Work Step by Step

a. The amplitude is the maximum displacement from equilibrium (the dotted line). Using a ruler on the diagrams shows that the amplitudes, greatest to least, are in the order stated. b. The wavelength is the distance between successive crests, troughs, or otherwise identical parts of a waveform. Using a ruler on the diagrams shows that the wavelengths, greatest to least, are in the order stated. Picture D only shows half of a complete cycle, so its wavelength is twice the distance between the points where the wave crosses the dotted line. c. Wave speed is frequency multiplied by wavelength. The wave speeds are the same, so a longer wavelength corresponds to a smaller frequency, and vice versa. The order here is the reverse of the order in part b. d. The period is the reciprocal of the frequency, so a longer period corresponds to a smaller frequency, and vice versa. The order here is the reverse of the order in part c.

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