Physics Waves DUHS 2022
PMDC Verified Question 64 of 125
The intensity level (sound level) of faintest audible intensity is:
A
160 decibel
B
0 decibel
C
140 decibel
D
120 decibel
Tap any option to test your recall and reveal the step-by-step Propolis autopsy.

Propolis Cognitive Error Autopsy

Official Correct Choice:
Option B: 0 decibel
Concept:

Sound intensity level (\( \beta \)) compares a given sound intensity (\( I \)) to the standard threshold of human hearing (\( I_0 = 10^{-12} \text{ W/m}^2 \)).

Formula:

$$ \beta = 10 \log \left( \frac{I}{I_0} \right) $$

Solution:

  • The "faintest audible intensity" is the threshold of hearing itself, meaning \( I = I_0 \).


  • Substitute this into the equation: \( \beta = 10 \log \left( \frac{I_0}{I_0} \right) \).


  • \( \beta = 10 \log(1) \).


  • Since \( \log(1) = 0 \), the intensity level is exactly 0 decibels.


Why other options are incorrect:

Options A, C, and D represent extremely loud sounds (above the threshold of pain), not the faintest audible sounds.

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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