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.
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Answer 1

Explanation:

No, the converse is not true. The basic requirements for a wave function to represent a travelling wave is that for all values of x and t, wave function must have finite value.

Out of the given functions for y, no one satisfies this condition. Therefore, none can represent a travelling wave.

Answer 2

(a) The reflected sound travals in the air therefore,

Speed of sound in air ( V) = 340 m/s

Frequency ( f) = 1000 kHz

                        = 10⁶ Hz

Wavelength = speed of wave /frequency of wave

= 340/10⁶ m

= 3.4 × 10⁻⁴ m

(b) speed of sound in water  = 1486 m/s

So, wavelength of transmitted wave will be equal to the speed  of sound in water/frequency

= 1486/10⁶ m

= 1.49 × 10⁻³ m