Physics Dawn of Modern Physics MDCAT 2017
PMDC Verified Question 47 of 52
The momentum of wave of wavelength \( 1.32 \times 10^{-9} \text{ m} \) is:
A
\( 5 \times 10^{-26} \text{ Ns} \)
B
\( 5 \times 10^{-25} \text{ Ns} \)
C
\( 5 \times 10^{-43} \text{ Ns} \)
D
\( 5 \times 10^{-44} \text{ Ns} \)
Tap any option to test your recall and reveal the step-by-step Propolis autopsy.

Propolis Cognitive Error Autopsy

Official Correct Choice:
Option B: \( 5 \times 10^{-25} \text{ Ns} \)
Concept:

The de Broglie wavelength relates a wave's spatial period to its physical momentum.

Formula:

$$ p = \frac{h}{\lambda} $$

Solution:

  • Use \( h = 6.63 \times 10^{-34} \text{ Js} \) and \( \lambda = 1.32 \times 10^{-9} \text{ m} \).


  • \( p = \frac{6.63 \times 10^{-34}}{1.32 \times 10^{-9}} \)


  • \( p = 5 \times 10^{-25} \text{ Ns} \) (or \( \text{kg m s}^{-1} \)).


Why other options are incorrect:

The other options result from incorrect manipulation of scientific notation exponents or using incorrect values for Planck's constant.

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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