The depth of a sea can be determined by using SONAR. Consider the following statements about it:
1. It uses ultrasonic waves for measurement of depth of a sea.
2. The speed of ultrasonic waves in sea water is the same as that of sound in air.
3. Time taken by the ultrasonic waves reflected from the bottom of the sea to reach the detector is used to measure the depth.
Which of the above statement(s) is/are correct?
Options
A3 only
B1 and 3 only
C2 and 3 only
D1, 2 and 3 only
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Correct Answer
B1 and 3 only
Model Answer
SONAR
Sound Navigation And Ranging (SONAR) is vital for exploring and mapping the ocean because sound waves travel farther in the water than radars and light waves.
It uses ultrasonic waves for the measurement of the depth of a sea along with the distance, direction and speed of underwater objects. Hence, statement 1 is correct.
Working
Sonar detects underwater objects by emitting ultrasonic waves into the sea and detecting the reflected echoes.
As soon as the ultrasonic waves are emitted, the Sonar switches to the receiving mode and listen for the returning ultrasonic echoes.
Here, the time taken by ultrasonic waves reflected from the bottom of the sea after striking, to reach the detector is used to measure the depth. Hence, statement 3 is correct.
It can detect and display the distribution, density, and movement of objects.
In the seas and oceans, the speed of sound varies between 1,450 and 1,570 m/s while the speed of sound in air is about 344m/s because the mechanical properties of water differ from the air.
Hence, statement 2 is incorrect.
A diagram of a ship's SONAR sending an ultrasound pulse from the transducer to the bottom of the sea and the reflected echo returning to the detector.
