Gujarat BoardEnglish MediumSTD 9ScienceSound1 Mark
MCQ
In $\text{SONAR},$ we use
✓
Ultrasonic waves.
B
Infrasonic waves.
C
Radio waves.
D
Audible sound waves.
✓
Answer
Correct option: A.
Ultrasonic waves.
$\text{SONAR} ($sound navigation ranging$)$ uses ultrasonic waves i.e. sounds having frequency greater than $20,000Hz.$
The reasons are:
They can penetrate water to long distances $($because of their high frequency and very short wavelength$)$ unlike ordinary sound waves or infrasonic waves.
Sound of these waves do not get mixed with engine noises or other sounds made by the ship. So, no confusion arises as these waves are not audible by human ear.
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