Question

(i) What is an echo?
(ii) State two conditions for an echo to take place.

Answer 1

(i) The sound heard after reflection from a distant obstacle after the original sound has ceased, is called an echo.

(ii) Two conditions for an echo to take place are:

(a) The minimum distance between the source of sound and the reflector must be $17m$

(b) The minimum time taken by the reflected sound to reach the listener should be $0.1s$