15.6 A bat emits an 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/sec and in water 1486 m/sec.

Frequency of the ultrasonic sound ν= 1000 kHz = 106 Hz 
Speed of sound in air, va=340 m/s 
The wavelength λr of the reflected sound:
λr=vν=340106=3.4×10-4 m
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: 
λr=1486106 = 1.49×10-3 m