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


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