Question

Explain the working and applications of SONAR.

Answer 1

Hint: SONAR is abbreviation of Sound Navigation and Ranging. It consists of a transmitter and receiver mounted on the ship. SONAR uses ultrasonic waves to measure the depth of the sea.

Complete answer:
We know SONAR is an abbreviation of Sound Navigation and Ranging. As the name suggests SONAR uses sound waves (ultrasonic) to measure the depth of the sea, movement and speed of the underwater objects.
We will explain the working of SONAR as follows,
It consists of a transmitter and receiver mounted on the ship. The transmitter transmits ultrasonic sound waves in the sea. These waves when incident on the sea-bed, get reflected towards the ship. These reflected ultrasonic waves are managed to detect by the receiver mounted at the base of the ship. We know that the receiver converts ultrasonic waves into electrical signals which can be used to detect the depth of the sea-bed.
Thus, we have seen that SONAR works on echo of the sound. The time required for the ultrasonic wave to reach the sea-bed or the certain object and then back to the ship is recorded. Then, we can use the relation between velocity, distance and time to determine the depth of the sea-bed as follows,
\[d = \dfrac{v}{t}\]
Here, v is the velocity of the sound wave and t is the time taken by the ultrasonic wave to reach the ship reflected from the sea-bed.
The applications of SONAR include determination of the depth of the sea, movement and speed of the underwater objects.

Note:
Since to measure the distance, we need the time taken by the sound wave to just reach the sea-bed. The relation between velocity, distance and time should be, \[2d = \dfrac{v}{t}\], to determine the depth of the sea. Here, d is the depth and not 2d.