General exam question G3A03
Subelement G3, RADIO WAVE PROPAGATION· Group G3A
Approximately how long does it take the increased ultraviolet and X-ray radiation from a solar flare to affect radio propagation on Earth?
- A.28 days
- B.1 to 2 hours
- C.8 minutes (correct answer)
- D.20 to 40 hours
WhyIt takes about 8 minutes for the increased ultraviolet and X-ray radiation from a solar flare to affect radio propagation on Earth. Light, and the flare's burst of ultraviolet and X-ray radiation travels at the same speed, takes about 8 minutes to cross the roughly 93 million miles from the Sun to Earth, so that's how quickly a flare's propagation effects show up, answer C. The much longer periods in A, B, and D describe other solar-terrestrial timescales, not how fast electromagnetic radiation itself arrives.
Published 2026-08-28 · Last updated 2026-08-28 · Question text is verbatim from the 2023-2027 NCVEC Element 3 pool (public domain); the explanation above is original writing, see our methodology.
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