NCERT Class 11 Physics Solutions: Chapter 15 – Waves-Part 3 (For CBSE, ICSE, IAS, NET, NRA 2022)

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Question 15.5:

You have learnt that a travelling wave in one dimension is represented by a function where must appear in the combination i.e.. Is the converse true? Examine if the following functions for y can possibly represent a travelling wave:

: Does not represent a wave

The converse of the given statement is not true. The essential requirement for a function to represent a travelling wave is that it should remain finite for all values of

Explanation:

For the function becomes

Hence, for , the function represents a point and not a wave.

: Represents a wave

Explanation:

For the function

Since the function does not converge to a finite value for , it represents a travelling wave.

: Does not represent a wave

Explanation:

For , the function

Since the function does not converge to a finite value for , it does no represent a travelling wave.

Question 15.6:

A bat emits ultrasonic sound of frequency in air. If the sound meets a water surface, what is the wavelength of,

The reflected sound,

The transmitted sound?

Speed of sound in air is

Frequency of the ultrasonic sound,

Speed of sound in air,

The wavelength of the reflected sound is given by the relation:

Frequency of the ultrasonic sound,

Speed of sound in water,

The wavelength of the transmitted sound is given as:

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