Sonar is a detection device that uses sound to locate underwater objects. The word sonar comes from the words sound navigation and ranging. Warships and military aircraft use sonar to locate enemy submarines. Ships also use sonar to determine the depth of the water beneath them. There are two main types of sonar, active sonar and passive sonar.

Active sonar sends out a sharp pulse of sound. This sound, which resembles a ‘ping’, is reflected back when it strikes on the object. The distance to the object is found by measuring the time taken by the sound to return.

Passive sonar simply listens for sound given off by possible targets. This type of sonar can determine the direction in which and object is located, but not its distance. However, a passive sonar system has the advantage of not giving off any sound that another sonar unit might detect.

NOTE : did you know that the sound waves used for sonar are of very high and are too high-pitched to be heard by the human ear.?