Wave speed, frequency and wavelength are locked together by one equation. Leave the one you want blank and this solves it, showing the rearrangement and the period as well.
Frequency is how many complete waves pass a point each second. Wavelength is how long one complete wave is. Multiply them and you get how far the wave travels in a second, which is its speed.
If 440 waves go past every second and each one is 0.78 m long, the wave front must have moved 440 × 0.78 = 343 m in that second. That is all the equation is saying.
The period T is the time for one complete wave to pass, measured in seconds. It is simply the reciprocal of frequency: T = 1 ÷ f. A 440 Hz note has a period of about 0.00227 s, because 440 waves fit into each second.
That also gives an alternative form of the wave equation, v = λ ÷ T, which some syllabuses prefer. It says the same thing: one wavelength travelled in one period.
| Quantity | Symbol | Unit |
|---|---|---|
| Wave speed | v | metres per second (m/s) |
| Frequency | f | hertz (Hz) |
| Wavelength | λ (lambda) | metres (m) |
| Period | T | seconds (s) |