Question

Which of the following types of waves is used in the SONAR device?
A. radio waves
B. audible sound waves
C. infrasonic waves
D. ultrasonic waves

Answer 1

Hint: In the Sound Navigation and Ranging instruments, we use waves which can penetrate to large distance or large depths in the water bodies. For this type of characteristics, the waves should have very high frequency.

Complete step by step solution:
SONAR is an abbreviation for Sound Navigation and Ranging. It is a technique in which we use sound waves to calculate distance. It is mostly used in marine vessels and submarines for navigation where a wave is emitted from the SONAR device and they hit the obstacle and reflect back towards the device which is able to calculate the distance using this information.
Now in order to obtain reliable information from the SONAR device, we need the waves which are able to penetrate through water bodies to large distances without getting absorbed on the way. This means that the waves should have a large amount of energy and energy is directly proportional to the frequency of the wave. This means that we need waves which have very high frequency.
The ultrasonic waves are most suitable because they have very high frequencies greater than 20kHz. They are most commonly used in SONAR devices as they do not get absorbed easily and perform reliable navigation and ranging. Hence the correct answer is option D.

Note: 1. The radio waves have very low frequencies and large wavelengths due to which they are unsuitable for SONAR application.
2. Infrasonic waves have very low frequencies less than 20Hz and also unsuitable for SONAR.
3. Audible sound waves have frequency between 20Hz and 20kHz and can defeat the purpose of SONAR since they are audible to human ears and can be detected easily when used in detecting enemy submarines.