Question

given that sound travels in air at 340m/s find the wavelength of the waves in air produced by 20KHz sound source . if the same sourceis put in a water tank what would be the wavelength of the sound waves in water? speed of sound in water = 1480m/s.



PLS ANSWER FAST.HAVE AN EXAM TOMORROW

Answer 1

we have velocity= wavelength*frequency
340/20000 will give wavelength in air.

Now v is 1480 in water and frequency is same as 20000 Hz (given)

with same formula ...calculate the wavelength in water

Answer 2

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• Sound is produced due to vibration of objects.

• Vibration is the rapid to and fro motion of an object.

WAVELENGTH : The distance two consecutive crest or two consecutive trough is called as wavelength.

It is denoted by a Greek letter : λ

S.I unit of wavelength is meter ( m ).

FREQUENCY : The number of oscillations per unit time is called frequency of the sound wave.

It is denoted by Greek letter ν ( nu ).

S.I Unit of the frequency is Hertz. ( Hz ).

→  

Speed of sound in air = 340 m/s.

Frequency =  20kH z  =  20  ×  10³ Hz

Wavelength = ?

Therefore,   Speed  = Wavelength × Frequency

                      v   =  λν

Therefore,    λ  =  v/ν = Speed / Frequency  = 340 /  20  ×  10³

                               =  0.017m.

Speed of sound in water  = 1480 m/s

Frequency      =   20  ×  10³ Hz

Wavelength    =  ?

Therefore, Speed = wavelength × Frequency

Wavelength  = Speed / Frequency

                     =  1480 / 20×10³  

                  =  0.074 m.