Physics Waves SZABMU 2022
PMDC Verified Question 79 of 125
The ultrasonic waves have frequency higher than:
A
20 Hz
B
20 kHz
C
200 Hz
D
2000 kHz
Tap any option to test your recall and reveal the step-by-step Propolis autopsy.

Propolis Cognitive Error Autopsy

Official Correct Choice:
Option B: 20 kHz
Concept:

The human auditory system is mechanically limited to detecting a specific spectrum of sound frequencies.

Solution:

  • A healthy human ear can perceive sound frequencies ranging from a low of 20 Hz up to a maximum high of 20,000 Hz (which is exactly 20 kHz).


  • Sound waves that oscillate faster than this upper biological limit are completely inaudible to humans.


  • The prefix "ultra-" means "beyond." Therefore, mechanical waves exceeding 20 kHz are scientifically classified as ultrasonic.


Why other options are incorrect:

Frequencies strictly below 20 Hz are termed "infrasonic." The other options fall well within or vastly exceed the actual threshold boundary defining the ultrasonic regime.

Quality & Fidelity Assurance: Every question on BeambePrep is rigorously curated against the official PMDC syllabus with zero filler, zero out-of-syllabus content, and zero typos. When an authentic past paper originally contained a historical mistake or ambiguity from the examining board (such as UHS or NUMS), BeambePrep faithfully reflects the original paper while detailing the nuance and scientific consensus in the autopsy above.

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