Basic Qualification · B-007 Radio wave propagation · B-007-002-003
Quelle est la couche ionosphérique la plus près de la Terre?
- ALa couche D
- BLa couche E
- CLa couche F
- DLa couche A
Correct answer: A — La couche D. Question tirée de la banque officielle d'ISDE.
Why
The D region is the correct answer because it forms the lowest layer of the ionosphere, sitting between 60 and 90 kilometres above the ground, making it the closest to Earth. 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