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 340 m s–1 and in water 1486 m s–1.

Answer 1

(a) The reflected sound travals in the air so,
Speed of sound in air ( V) = 340 m/s
Frequency ( f) = 1000kHz = 10^6 Hz

Wavelength = speed of wave /frequency of wave
= 340/10^6
= 3.4 × 10^-4 m


(b) speed of sound in water ( Vw) = 1486 m/s
So, wavelength of transmitted wave = speed of sound in water/frequency
= 1486/10^6
= 1.49 × 10^-3 m