Which statement about wavelength is true?

Which statement about wavelength is true?

• A. Wavelength is determined only by the source
• B. Wavelength is determined only by the medium
• C. Wavelength is determined by neither the source nor the medium
• D. Wavelength is determined by both the source and the medium

Answer: (D)

Wavelength comes from how fast a wave travels in a medium and how often the source makes the wave. The relationship is λ = v / f, where v is the speed in the medium and f is the frequency set by the source. The source fixes the frequency, and the medium fixes the speed. Because the speed changes with the medium, the wavelength must change as well, even if the frequency stays the same. So the wavelength depends on both the source (through its frequency) and the medium (through its wave speed). For example, light has the same frequency when it moves from air into water, but its speed drops and its wavelength shortens in water.

Wavelength comes from how fast a wave travels in a medium and how often the source makes the wave. The relationship is λ = v / f, where v is the speed in the medium and f is the frequency set by the source. The source fixes the frequency, and the medium fixes the speed. Because the speed changes with the medium, the wavelength must change as well, even if the frequency stays the same. So the wavelength depends on both the source (through its frequency) and the medium (through its wave speed). For example, light has the same frequency when it moves from air into water, but its speed drops and its wavelength shortens in water.