Which formula correctly relates wavelength, speed, and frequency?

Which formula correctly relates wavelength, speed, and frequency?

• A. Wavelength = Speed - Frequency
• B. Wavelength = Frequency / Speed
• C. Wavelength = Speed * Frequency
• D. Wavelength = Speed / Frequency

Answer: (D)

When a wave travels, its speed is the product of its wavelength and its frequency: v = λ f. This makes sense because one complete wave cycle spans a distance equal to the wavelength, and cycles pass each second at a rate equal to the frequency, so distance per second is λ times f. Rearranging gives λ = v / f, which is the correct way to relate wavelength, speed, and frequency. In units, meters per second divided by cycles per second (hertz) yields meters, as expected for a length. So the wavelength is speed divided by frequency. The other forms don’t reflect the actual proportionality and would not have the correct units.

When a wave travels, its speed is the product of its wavelength and its frequency: v = λ f. This makes sense because one complete wave cycle spans a distance equal to the wavelength, and cycles pass each second at a rate equal to the frequency, so distance per second is λ times f. Rearranging gives λ = v / f, which is the correct way to relate wavelength, speed, and frequency. In units, meters per second divided by cycles per second (hertz) yields meters, as expected for a length.

So the wavelength is speed divided by frequency. The other forms don’t reflect the actual proportionality and would not have the correct units.