Physics Waves PMDC 2021
PMDC Verified Question 87 of 125
Doppler's effect shows?
A
Change in frequency due to relative motion between source and observers
B
Change in amplitude due to relative motion between source and observer
C
Change in frequency due to motion of source only
D
Change in frequency due to motion of observer only
Tap any option to test your recall and reveal the step-by-step Propolis autopsy.

Propolis Cognitive Error Autopsy

Official Correct Choice:
Option A: Change in frequency due to relative motion between source and observers
Concept:

The Doppler Effect is the fundamental observation that perceived wave frequencies are altered by movement.

Solution:

  • The core definition of the Doppler effect is an apparent change in frequency (or pitch) resulting from the relative motion between the wave's source and the observer.


  • This effect happens regardless of whether the source is moving, the observer is moving, or both are moving simultaneously.


Why other options are incorrect:

Option B is wrong because the primary physical change is in frequency (pitch/color), not amplitude (loudness/brightness). Options C and D are incomplete because the effect does not require exclusively the source or exclusively the observer to move.

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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