Physics Waves NUMS 2024
PMDC Verified Question 22 of 125
A normal person can hear sound waves ranging in frequency from 20 Hz to 20 K Hz. The maximum wavelength is:
A
17 m
B
17 mm
C
17 cm
D
17 km
Tap any option to test your recall and reveal the step-by-step Propolis autopsy.

Propolis Cognitive Error Autopsy

Official Correct Choice:
Option A: 17 m
Concept:

Wavelength is inversely proportional to frequency. Therefore, the lowest frequency sound will mathematically yield the longest (maximum) wavelength.

Formula:

$$ \lambda = \frac{v}{f} $$

Solution:

  • To find the maximum wavelength, we must use the minimum audible frequency, which is \( f = 20 \text{ Hz} \).


  • Assume the standard speed of sound in room-temperature air is roughly \( v \approx 340 \text{ m/s} \).


  • Substitute the values: \( \lambda_{max} = \frac{340}{20} \).


  • \( \lambda_{max} = 17 \text{ m} \).


Why other options are incorrect:

Options B (17 mm) and C (17 cm) correspond to the high-frequency limit (20,000 Hz), which yields the minimum, not maximum, wavelength. 17 km is completely out of scale.

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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