Question

Ultrasonic waves are those waves:

• A. which a man can hear
• B. which a man cannot hear
• C. which are of high velocity
• D. which are of high amplitude

Answer 1

The correct option is B

which a man cannot hear

1. The audible range of humans is from $20Hz-20000\hspace{0.17em}Hz$
2. Sound of frequencies above $20000Hz$ are called ultrasonic sounds..
3. So clearly it is not audible to the human

Hence, option B is correct.