Extra exam question E3C10
Subelement E3, RADIO WAVE PROPAGATION· Group E3C
What does the 304A solar parameter measure?
- A.The ratio of X-ray flux to radio flux, correlated to sunspot number
- B.UV emissions at 304 angstroms, correlated to the solar flux index (correct answer)
- C.The solar wind velocity at an angle of 304 degrees from the solar equator, correlated to geomagnetic storms
- D.The solar emission at 304 GHz, correlated to X-ray flare levels
WhyThe 304A solar parameter measures UV emissions at 304 angstroms, correlated to the solar flux index. The 304A solar parameter tracks solar ultraviolet emissions specifically at the 304 angstrom wavelength, a proxy that correlates well with the traditional 10.7 cm solar flux index and offers another way to gauge overall solar activity, answer B. It isn't an X-ray-to-radio-flux ratio, isn't a solar wind velocity measurement, and 304 in its name refers to a wavelength in angstroms, not a frequency in gigahertz.
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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