FIGURE 5.10 The physical properties of waves (a) Waves vary in wavelength (the distance between successive peaks). Frequency, the number of complete wavelengths that can pass a point in a given time, depends on the length of the wave. The shorter the wavelength, the higher the frequency. Wavelength determines the perceived color of light (and also the pitch of sound). (b) Waves also vary in amplitude, the height from peak to trough (top to bottom). Wave amplitude determines the perceived brightness of colors (and also the intensity of sounds).