Wavelength depends on which two factors?

• A. Frequency and amplitude
• B. Amplitude and propagation speed
• C. Period and frequency
• D. Frequency and propagation speed

Answer: (D)

Wavelength is the distance a single cycle of the wave travels in space, so it depends on how fast the wave moves and how often cycles occur. The relationship is λ = v / f, where v is the propagation speed and f is the frequency. Since f = 1/T, you can also see λ = v × T. This shows why speed and frequency uniquely determine wavelength.

Amplitude does not affect wavelength—it changes how much energy the wave carries, not its spacing. Period is the time for one cycle; knowing period alone doesn’t give the spatial length without also knowing how fast the wave is moving, and the period–frequency pair is redundant once you include speed.