Wave Speed Calculator
v = fλ, solved for whichever you are missing.
Work out Wave Speed. v = fλ, solved for whichever you are missing. Written for the problem set you are stuck on.
Sound in air 343, in water 1481, light 2.998e8.
Frequency
686 Hz
v = fλ · period 0.001458 s
v = fλ holds for every wave — sound, light, water, a rope. What changes between them is which quantity is fixed by the medium. Wave speed is a property of the medium, not the source. When sound passes from air into water the frequency stays the same, because the source is still vibrating at the same rate, so the wavelength must stretch by the ratio of the speeds — 4.3 times. That is also why frequency and not wavelength is the safe way to describe light. Wavelength shortens inside glass or water while frequency does not, so a 500 nm laser is only 500 nm in vacuum.
How the Wave Speed Calculator works
Solve v = fλ for speed, frequency or wavelength. The relationship holds for every wave there is — sound, light, water, a rope — and what changes between them is only which quantity the medium fixes.
Also known as: wavelength frequency calculator · v = f lambda calculator · frequency to wavelength converter · wave equation calculator
Frequently asked questions
What is the wave equation?
v = fλ. Wave speed equals frequency times wavelength, and it applies to every kind of wave without exception.
What happens when sound goes from air into water?
The frequency stays the same, because the source is still vibrating at the same rate. The speed rises about 4.3 times, so the wavelength must stretch by the same factor.
Does wave speed depend on frequency?
Not in a non-dispersive medium — sound in air travels at 343 m/s whatever the pitch, which is why music arrives in order. In dispersive media it does, which is exactly why a prism splits white light.
Why quote light by frequency rather than wavelength?
Because wavelength shortens inside glass or water while frequency does not. A 500 nm laser is only 500 nm in vacuum, so frequency is the portable description.
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