Question

Explain the working and application of SONAR

Answer 1

SONAR  is a device used by ships and submarines to locate the position of other vessels in the ocean. these are of 2 types: one is passive which only detects the incoming. another one is active SONAR which transmits sound pulses and detects the reflected echoes to detect the presence of other sea vessels.
principle behind sonar is reflection of sound.
the sound sent is reflected back from the sea bed which is known as echo.
let the depth of the ocean be D 
for perpendicular focusing of the sonar 
V=2D/t
D=Vt/2
where V is speed of sound in water
t is the time after the echo is detected
thus the depth of the ocean is evaluated.
SONAR is a very powerful technique which can help determine what lies beneath the ship, boat or submarine. it has been used to discover shipwrecks, lost treasures etc
it is also used in military for detecting  the presence of enemy ships.

Answer 2

this is the answer of that question