Question

explain the working process and application of sonar

Answer 1

SONAR-SOund NAvigation and Ranging. It is a device used to measure the deapth of sea,speacially used in ships and submarines.

WORKING:
A transmitter kept at the base of the ship,transmitts a Ultrasound.into the sea,the ultrasound hitting the seasbed reflects and comes back,whih is detected by a detector in the ship.

CALCULATION
Speed=distance/time
Distance=speed × time (here distance= two times the depth,beacuse it is reflected back from the sea bed)

2d=speed of sound × time taken to detect the ultrasound by the ship.

2d=1484m/sec(in water) × time taken

Answer 2

$\Large{\underline{\underline{\bf{Solution :}}}}$

★ SONAR :

The word 'SONAR' stands for

Sound Navigation and Ranging.

♦ Principle of Sonar : Sonar is an apparatus which is used to find the depth of a sea or to locate the under water things like shoals of fish, enemy submarines etc. Sonar works by sending short bursts of ultrasonic sound from a ship down into sea water and then gets echo produced by the reflection of ultrasonic sound from under-water objects like bottom of sea, shoal of fish, a submarine.

♦ Working of Sonar :

(i) A transmitter (for emitting ultrasonic waves)

(ii) a receiver (for detecting ultrasonic waves). Now suppose a sonar device is attached to the under-side of a ship and we want to measure the depth of sea (below the ship). To do this the transmitter of sonar is made to emit a pulse of ultrasonic sound with a very high frequency of about 50,000 hertz. This pulse of ultrasonic sound travels down in the sea-water towards the bottom of the sea. When the ultrasonic sound pulse strikes the bottom of the sea, it is reflected back to the ship in the form of an echo. This echo produces and electrical signal in the receiver part of the sonar device. The sonar device measures the time taken by the ultrasonic sound pulse to travel from the ship to the bottom of the sea and back to the ship. Half of this time gives the time taken by the ultrasonic to travel from the ship to the bottom of the sea.

d = Depth of sea

v = Velocity of sound in sea water

t = time recorded by the recorder

$\Large{\implies{\boxed{\boxed{\sf{v = \frac{2d}{t}}}}}}$