Basic Qualification · B-007 Radio wave propagation · B-007-006-008
What happens daily when the solar UV radiation increases?
- A Weather in the ionosphere changes
- B The maximum usable frequency increases
- C The atmospheric noise level decreases
- D Ground wave propagation decreases
Correct answer: B — The maximum usable frequency increases. From the official ISED question bank, verified word for word.
Why
When solar ultraviolet radiation increases, it ionizes the upper atmosphere more strongly, creating denser layers of charged particles that can reflect higher radio frequencies back to Earth. The full explanation — and one for every question — is in Pro.
Practise this section
How signals travel: the ionosphere and its layers, skip, ground wave, sporadic E, and which bands work when.