Explain the working and application of a sonar.

SONAR is an abbreviation for SOund Navigation And Ranging. It is an acoustic device used with the help of ultrasounds to measure the depth, direction, and speed of underwater objects like submarines. It is also used to determine sea and ocean depths.

The SONAR produces and transmits an ultrasonic sound beam. The echo produced by the reflection of this ultrasonic sound is detected and recorded by the detector, which is converted into electrical signals.

The distance ($d$) of the under-water object is calculated using the time (t) taken by the echo to return with speed ($v$) is given by

                                                        $2d = v\times t$

This method of measuring distance is termed as ‘echo-ranging’.