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Question
A bat emits an ultrasonic sound of frequency 1000 kHz in the air. If the sound meets a water surface, what is the wavelength of the transmitted sound? The speed of sound in air is 340 m s–1 and in water 1486 m s–1.
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Solution 1
Frequency of the ultrasonic sound, ν = 1000 kHz = 106 Hz
Speed of sound in water, vw = 1486 m/s
The wavelength of the transmitted sound is given as:
`lambda_"t" = 1486/10^6`
= 1.49 × 10–3 m
Solution 2
Here v = `1000 xx10^3` Hz = 10^6 Hz, `v_a = 340 ms^(-1)`
`v_w = 1486 ms^(-1)`
Wavelenght of transmitted sound, `lambda_omega`
`= "v"_"w"/"v" = 1486/10^6 "m"`
`= 1.486 xx 10^(-3)` m
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