Question

define echo. state two condition of echo to heard.

Answer 1

Reflection of sound is known as echo.

Conditions for a successful echo:

■ Minimum distance from the source to the reflected object must be 17.2 m

■ Atleast 0.1 second of sound interval must be there.

I hope this helps!

Answer 2

To hear a distinct echo, the time interval between the original sound and the reflected one must be at least 0.1 s.
(ii) For hearing distinct echoes, the minimum distance of the obstacie from the source of sound must be 17.2 m.
Echo is a repetition of sound due to the reflection of original sound by a broad and hard obstacle.