Wave speed equation
Wave speed = frequency x wavelength (v = f x lambda), measured in m/s.
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Analogy
If 4 people pass a gate each second and each is 2 m long, the line moves at 8 m/s.
Example
f = 5 Hzwavelength = 0.2 mv = 5 x 0.2v = 1 m/s
In practice
Used to find the wavelength of a radio station or the speed of ripples in a tank.
Practice
Flashcards
- What is the wave speed equation?Wave speed = frequency x wavelength.
Interview questions
- A water wave has a frequency of 4 Hz and a wavelength of 0.5 m. Calculate its speed and say how far it travels in 10 s.
- v = f x wavelength = 4 x 0.5 = 2 m/s
- Distance = speed x time = 2 x 10
- Distance = 20 m
Questions people ask
How do I use v = f x wavelength?
Put frequency in hertz and wavelength in metres, then multiply to get speed in m/s. To find wavelength, divide speed by frequency. A wave with speed 340 m/s and frequency 170 Hz has a wavelength of 340 / 170 = 2 m.
If frequency increases, what happens to wavelength?
In a given material the wave speed is fixed. So if frequency goes up, wavelength must go down to keep v = f x wavelength true. High-pitched sounds have short wavelengths, and low-pitched sounds have long ones, even though both travel at about the same speed in air.