Physics Alternating Current PMDC Conceptual Practice
PMDC Verified Question 70 of 127
Which of the following electromagnetic radiations travels at the greatest speed in vacuum?
A
Gamma rays
B
Radio waves
C
All electromagnetic waves travel at the exact same speed
D
X-rays
Tap any option to test your recall and reveal the step-by-step Propolis autopsy.

Propolis Cognitive Error Autopsy

Official Correct Choice:
Option C: All electromagnetic waves travel at the exact same speed
Concept:

All electromagnetic waves, regardless of frequency, wavelength, or photon energy, propagate through vacuum at the universal speed of light \(c\).

Formula / Reaction:

$$c = \frac{1}{\sqrt{\mu_0 \varepsilon_0}} = 3.00 \times 10^8\text{ m/s}$$

Solution:

  • Speed in vacuum is a fundamental constant determined only by \(\mu_0\) and \(\varepsilon_0\).


  • Radio waves, gamma rays, and X-rays all travel at identical speed \(c\).


Why other options are incorrect:

  • Opt_A, Opt_B, Opt_D: Incorrect because no electromagnetic wave travels faster than \(c\) in free space.

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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