Basic Qualification · B-007 Radio wave propagation · B-007-005-002
Quelle est la durée moyenne d'un cycle de taches solaires?
- A11 ans
- B17 ans
- C5 ans
- D7 ans
Correct answer: A — 11 ans. Question tirée de la banque officielle d'ISDE.
Why
The Sun goes through a regular pattern where the number of sunspots, which are dark, cooler areas on its surface, rises and falls over time. The full explanation — and one for every question — is in Pro.
Practise this section
Radio wave propagation is section B-007 of the Basic exam: How signals travel: the ionosphere and its layers, skip, ground wave, sporadic E, and which bands work when.
Drill B-007 — free, no account