A bat emits ultrasonic sound of frequency 1000 kHz in air. If the sound meets a water surface, what is the wavelength of (i) the reflected sound, (ii) the transmitted sound ? Speed of sound in air is 340 `ms^(-1)` and in water `1486 ms^(-1)`.

Explanation

(a) Frequency of the ultrasonic sound, `ν = 1000 kHz = 10^(6) Hz`
Speed of sound in air,` v_(a)` = 340 m/s
The wavelength `(lambdar)` of the reflected sound is given by the relation:
`lambda_(r)=(u)/(v)`
`=(340)/(10^(6))=3.4 xx 10^(-4) m`
(b) Frequency of the ultrasonic sound, ν = 1000 kHz = `10^(6)` Hz
Speed of sound in water, vw = 1486 m/s
The wavelength of the transmitted sound is given as:
`lambda_(1)=(1486)/(10^(6))=1.49xx 10^(-3) m`