General exam question G3A05
Subelement G3, RADIO WAVE PROPAGATION· Group G3A
G3A05
What is the solar flux index?
- A.A measure of the highest frequency that is useful for ionospheric propagation between two points on Earth
- B.A count of sunspots that is adjusted for solar emissions
- C.Another name for the American sunspot number
- D.A measure of solar radiation with a wavelength of 10.7 centimeters (correct answer)
WhyThe solar flux index measures solar radiation at a wavelength of 10.7 centimeters. The solar flux index directly measures the Sun's radio emission at a 10.7 centimeter wavelength, a proxy that correlates closely with how ionized the upper atmosphere is likely to be, answer D. It's not itself a measure of MUF, an adjusted sunspot count, or simply another name for the American sunspot number, those are related but distinct measurements.
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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