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A bat emits ultrasonic sound of frequenc...

A bat emits ultrasonic sound of frequency 100 kHz in air. If this sound meets a water surface, the wavelengths of the reflected and transmitted sound are (Speed of sound in air = 340 m `s^(-1)` and in water = 1500 m `s^(-1)` )

A

3.4 mm, 30 mm

B

6.8 mm, 15 mm

C

3.4 mm, 15 mm

D

6.8 mm, 30 mm

Text Solution

Verified by Experts

The correct Answer is:
C
Here, `v = 100" kHz" = 100 xx 10^(3)" Hz" = 10^(5)" Hz" = 10^(5)" s"^(-1)`
`v_a = 340" m s"^(-1), v_w = 1500"m s"^(-1)`
Frequency of both the reflected and transmitted sound remains unchanged.
Wavelength of reflected sound,
`lambda_1 = (v_a)/( upsilon) = (340"m s"^(-1) )/( 10^(5)" s"^(-1)) = 34 xx 10^(-4)" m"`
`= 3.4 xx 10^(-3)"m" = 3.4`mm
Wavelength of transmitted sound,
`lambda_w = (v_w)/( upsilon) = (1500"m s"^(-1) )/( 10^(5)" s"^(-1) ) = 15 xx 10^(-3)" m" = 15" mm"`
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A bat emits ultrasonic sound of frequency 1000 kHz in air. If the sound meets a water surface, what is the wavelength of (a) the reflected sound, (b) the transmitted sound ? Speed of sound in air is 340 ms^(-1) , and in water 1486 ms^(-1) .

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Knowledge Check

  • A bat flying above lake emits ultrasonic sound of 100 kHz ,When this wave falls on the water surface, it is partly reflected and partly transmitted .The wavelengths of the reflected and the transmitted waves are (The speed of sound in air is 340 m/s and in water is 1450 m/s)

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    B
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