Physics Alternating Current PMDC Conceptual Practice
PMDC Verified Question 40 of 127
Which optical phenomenon uniquely proves that light waves and other electromagnetic waves are strictly transverse rather than longitudinal?
A
Interference
B
Diffraction
C
Refraction
D
Polarization
Tap any option to test your recall and reveal the step-by-step Propolis autopsy.

Propolis Cognitive Error Autopsy

Official Correct Choice:
Option D: Polarization
Concept:

Polarization is the restriction of wave oscillations to a single plane perpendicular to the direction of propagation. Only transverse waves can be polarized.

Formula / Reaction:

$$I = I_0 \cos^2\theta \quad \text{(Malus's Law)}$$

Solution:

  • Longitudinal waves (such as sound) oscillate parallel to propagation and have complete cylindrical symmetry, so they cannot be polarized.


  • Because light can be polarized using polarizers, it must consist of transverse oscillations.


Why other options are incorrect:

  • Opt_A: Interference occurs in both transverse (light) and longitudinal (sound) waves.


  • Opt_B: Diffraction occurs in all wave types.


  • Opt_C: Refraction is common to all waves when entering a medium of different wave speed.

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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