Reasoning The distance between adjacent crests is the wavelength l. Crest The crest is the highest point of a wave. Wavelength Easy Science Physics Lessons Science Flashcards 4th Grade Science The distance between two successive crests or troughs is the wavelength λ. . Its SI unit is metre. The higher the amplitude of a wave the higher its energy. The distance between two corresponding crests on any type of wave is called a wavelength. The horizontal distance between two adjacent crests or troughs is known as the wavelength. The number of times the wave crosses a point in a second is known as the frequency of the wave. In fact the distance between the same point on any two successive waves is the same distance as the wavelength. The distance between two consecutive crests or consecutive troughs or compressionsrarefactions in a longitudinal waves is called the wavelength of a wave. Thus the distance between...