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A dolphin emits ultrasound at 100kHz and uses the timing of reflections to determine the position of objects in the water.

What is the wavelength of this ultrasound? Assume that temperature of water is 20 degrees C. Answer in cm

User Neouyghur
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1 Answer

1 vote

Answer: 14.82 cm

The speed
v of a wave (the sound in this case) is given by the following formula:


v=f.\lambda (1)

Where:


f=100kHz=100(10)^(3)Hz is the frequency


\lambda the wavelength

It is known that the speed of sound in water at
20\ºC is:


v=1482(m)/(s)

So, we only have to find
\lambda from (1):


\lambda=(v)/(f) (2)


\lambda=(1482(m)/(s))/(100(10)^(3)Hz)

Knowing
1Hz=(1)/(s):


\lambda=0.01482m

But we were asked to find the wavelength in cm and we have to make the conversion:


\lambda=0.01482m.(100cm)/(1m)=14.82cm

Hence:


\lambda=14.82cm

User Jakuje
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