Question

How do the following use echoes?

(a) army

Answer 1

Step 1:

Echo:

Echo is defined as the phenomenon due to which repetition of sound is heard after reflection from a distant object such as hillock or high building, after the original sound from a given source dies off.

Step 2:

• Army used echoes to locate enemy gun positions.
• To locate an enemy air-craft they used an instrument called radar.