Question

what is an echo? what factor are important to get a distinct echo?​

Answer 1

Echo is the sound heard after reflection from a rigid surface such as cliff , a hillside ,the wall of a building etc...

Factors

-The minimum distance between the source of reflector of sound should be 17 cm

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




Hope it helps you

Answer 2

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An echo is the repetition of the original sound because of reflection by some surface.

At 22°C, the velocity of sound in air is 344 m/s.

Our brain retains a sound for 0.1 s. Thus, for us to be able to hear a distinct echo, the sound should take more than 0.1 s after starting from the source to get reflected and come back to us.

We know that,

Distance = speed × time

= 344 m/s × 0.1 s

= 34.4 m

Thus, to be able to hear a distinct echo, the reflecting surface should be at a minimum distance of half of the above i.e. 17.2 m.

As the velocity of sound depends on temperature of air, this distance depends on the temperature.