NCERT Class 11 Physics Solutions: Chapter 15 – Waves-Part 14

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Question 15.25:

A system fixed in a submarine operates at a frequency . An enemy submarine moves towards the with a speed of What is the frequency of sound reflected by the submarine? Take the speed of sound in water to be

Answer:

Operating frequency of the SONAR system,

Speed of the enemy submarine,

Speed of sound in water,

The source is at rest and the observer (enemy submarine) is moving toward it. Hence, the apparent frequency received and reflected by the submarine is given by the relation:

The frequency received by the enemy submarine is given by the relation:

Where,