Extra exam question E3A10
Subelement E3, RADIO WAVE PROPAGATION· Group E3A
What determines the speed of electromagnetic waves through a medium?
- A.Resistance and reactance
- B.Evanescence
- C.Birefringence
- D.The index of refraction (correct answer)
WhyThe speed of an electromagnetic wave through a medium is determined by that medium's index of refraction. The speed of an electromagnetic wave passing through any given medium is set by that medium's index of refraction, which describes how much the medium slows the wave compared to its speed in a vacuum, answer D. Resistance and reactance describe electrical circuit properties, evanescence describes a non-propagating decaying field, and birefringence describes a material splitting light into two rays, none of them is what actually sets wave speed through a medium.
Published 2026-08-28 · Last updated 2026-08-28 · Question text is verbatim from the 2024-2028 NCVEC Element 4 pool (public domain); the explanation above is original writing, see our methodology.
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