Question

What is echo? and what are the conditions for echo to be heard?

Answer 1

Reflection of sound waves is called echo.

Conditions to be heard

Distance between source and reflecting surface must be 17.2 m

Time interval between original sound and reflected sound must be 0.1 seconds

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Answer 2

Echo :

The reflection of sound from a distant obstacle after the original sound has ceased is called an echo .

The conditions are as follows :

(i) The minimum distance should be 17 m between the reflecting surface and source.

(ii) The intensity of sound should be large enough .

(iii) The size of reflector should be large enough .