Question

what is an echo? what factors are important to get distinct echo???​

Answer 1

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Defination of echo :-An echo is a sound which is caused by a noise being reflected off a surface such as a wall.
Factors to get distinct echo are as follows: -
For hearing an echo, the obstacle must be situated at a suitable distance from the source. Due to persistence of hearing the sound must take at least 1/10* of a second in reaching the listener. If d is the minimum distance of the reflecting object from the source, then time t taken to cover the distance 2d must be 1/10 th second. '
Therefore, t = 2d/V or d= Vxt/2 = 340 x 1/20
= 17 m.
Echoes are not heard in a small room because the distance is less than the minimum distance of 17 m required for hearing the echo distinctly.

Answer 2

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The repetition of sound caused by its reflection off a hard surface is known as echo .

Factors important to get a distinct echo are :

• The maximum distance between the source and reflector of sound should be 17 m.

• The size of reflector must be large enough as compared to the wavelength of the sound wave .