Which statement correctly defines the wavelength of a wave?

Which statement correctly defines the wavelength of a wave?

• A. Wavelength is the distance between successive crests or successive troughs
• B. Crest is the maximum value of the wave
• C. Amplitude is the distance from the middle to the crest
• D. Trough is the minimum value of the wave

Answer: (A)

Wavelength is the spatial period of a wave—the distance over which the wave’s pattern repeats. The distance between successive crests (or between successive troughs) is the wavelength because after you move that amount along the direction of travel, the wave looks the same again. Crest is the maximum displacement, which is a height measure, not a spacing; that height is called the amplitude when measured from the middle of the wave. Trough is the minimum displacement, also a height measure, not spacing. So the first statement correctly defines what wavelength is.

Wavelength is the spatial period of a wave—the distance over which the wave’s pattern repeats. The distance between successive crests (or between successive troughs) is the wavelength because after you move that amount along the direction of travel, the wave looks the same again. Crest is the maximum displacement, which is a height measure, not a spacing; that height is called the amplitude when measured from the middle of the wave. Trough is the minimum displacement, also a height measure, not spacing. So the first statement correctly defines what wavelength is.