Define echo?Give its two applications.
Reflection of sound finds its applications in the construction of megaphone, bulb horn, stethoscope, soundboard etc. All these devices involves multiple reflections of sound waves.
Anechois areflectionof sound, arriving at the listener some time after the direct sound. Typical examples are the echo produced by the bottom of a well, by a building, or by the walls of an enclosed room and an empty room. A true echo is a single reflection of the sound source. The time delay is the extra distance divided by thespeed of sound.The minimum distance of the origin of the sound from the reflecting surface must be 17.2m to hear a distinct echo.
Echoes a generally used by bats to find their prey in the dark. Echoes are also used to measure our heart beats by a device called Cardieogram .