Establish the relationship between speed of sound, its wavelength and frequency. If velocity of sound in air is 340 m s-1, calculate
(i) Wavelength when frequency is 256 Hz.
(ii) Frequency when wavelength is 0.85 m.
Frequency and time period are related as follows: √ = (I)
We know, Speed, v =
v =
Here λ is the wavelength of the sound wave. It is the distance traveled by the sound wave in one time-period (T) of the wave.
Thus,
v = λ√ (From I)
That is, Speed = wavelength * Frequency
The speed of sound remains almost the same for all frequencies in a given medium under the same physical conditions.
(i) Given, Speed (v) = 340 m/s
Frequency (√) = 256 Hz
Wavelength (λ) =?
v = λ√
340 = 256λ
λ = 1.33 m
(ii) Given, Speed (v) = 340 m/s
Wavelength (λ) = 0.85 m
Frequency (√) =?
v = λ√
340 = √ (0.85)
√ = 400 Hz