Question

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 $340m{s}^{-1}$ and in water $1486m{s}^{-1}$.

Answer 1

Frequency of the ultrasonic sound, $\nu =1000kHz={10}^{6}Hz$
Speed of sound in air, $v_a=340m/s$
The wavelength $\left({\lambda }_r\right)$ of the reflected sound is given by the relation:
${\lambda }_r=\frac{v}{v}=\frac{340}{{10}^6}=3.4\times {10}^{-4}m$
Frequency of the ultrasonic sound, $\nu =1000kHz={10}^{6}Hz$
Speed of sound in water, $v_w$ = 1486 m/s
The wavelength of the transmitted sound is given as:
${\lambda }_r=\frac{1486}{{10}^6}=1.49\times {10}^{-3}m$