Multiple choice

What are ultrasonic waves?

  1. Sound waves having frequency less than the audio frequency range.

  2. Sound waves produced in vacuum.

  3. Sound waves having frequency higher than audio frequency range.

  4. None of these
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

Ultrasonic waves are sound waves with frequencies above the upper limit of human hearing (typically >20 kHz). Option A incorrectly describes frequencies below the audio range, and sound cannot propagate in vacuum (eliminating B). C correctly states that ultrasonic waves have higher frequencies than the audible range.

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