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. | Learn NCERT solution | Education portal Class 11 Physics | Study online Unit-15 Waves



Q.6:- 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:-



(a) 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 is given by the relation:
λ= v/v
= 340/106 = 3.4 × 10-4 m.

(b) 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:
λ= 1486 × 10= 1.49 × 10-3 m.