Question

Give scientific reasons:

An echo is not heard in a small room but it can be heard in hills near ravines.

Answer 1

1. We cannot hear an echo in a small room because in it the sound cannot be reflected back.
2. For an echo to be heard the minimum distance between the source of sound and the walls of the room should be 17.2 m. So it is not possible in a small room.
3. While in hills the distance between the source of sound and the reflecting surface is greater than 17.2 m, that is why we can easily hear an echo in hills.