Basic Qualification · B-007 Radio wave propagation · B-007-005-007
When sunspot numbers are high, how is propagation affected?
- AFrequencies up to 40 MHz or even higher become usable for long-distance communication
- BHigh frequency radio signals are absorbed
- CFrequencies up to 100 MHz or higher are normally usable for long-distance communication
- DHigh frequency radio signals become weak and distorted
Correct answer: A — Frequencies up to 40 MHz or even higher become usable for long-distance communication. From the official ISED question bank, verified word for word.
Why
When sunspot numbers are high, the Sun's increased radiation strengthens the ionosphere, the upper atmospheric layer that reflects radio waves back 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