Wave Speed (v = fλ)
Also known as v = fλ · wave equation · frequency times wavelength
Worked example: Sound at 1234.8 km/h, 0.5 kHz → lambda = 0.686 m — press Try an example to run it live, then adjust anything.
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Wave Speed (v = fλ) explained
Every traveling wave advances exactly one wavelength during each cycle of its source, and it completes f cycles every second — so its speed is simply frequency times wavelength. The relation holds for every wave in nature: sound, light, water ripples, seismic tremors. An FM station broadcasting at 100 MHz emits radio waves that travel at the speed of light, about 3.00 × 10⁸ m/s, so each wave is roughly 3 m long — which is why FM antennas are built around three-quarters of a metre, a quarter of a wavelength.
The common trap is thinking a higher frequency makes a wave faster. It doesn't: speed is set by the medium alone. Sound in room-temperature air moves at about 343 m/s whether it is a 20 Hz bass rumble (λ ≈ 17 m) or a 20 kHz whistle (λ ≈ 17 mm). Raise the frequency and the wavelength shrinks in exact proportion, leaving v untouched.
Wave Speed (v = fλ) formula
- = Wave speed (m/s)
- = Frequency (Hz)
- = Wavelength (m)
Missing one of these? Work it out first, then come back
- Wave speed — Wave Speed on a String, Fundamental Frequency of a String
- Frequency — Period-Frequency Relation, Inductive Reactance (X_L = 2πfL)
- Wavelength — Double-Slit Fringe Spacing, Diffraction Grating Equation