Deep Dive: G3A11
The correct answer is D: 15 hours to several days. It takes 15 hours to several days for a coronal mass ejection (CME) to affect radio propagation on Earth. CMEs are clouds of charged particles that travel much slower than light, taking 1-4 days typically. For amateur radio operators, this is much slower than solar flare radiation (8 minutes). Understanding this helps predict when CME effects will occur.
Why Other Answers Are Wrong
Option A (28 days): Incorrect. 28 days is the solar rotation period, not CME travel time. CMEs take much less time (hours to days). Option B (14 days): Incorrect. 14 days is too long - typical CME travel time is 1-4 days, not 14 days. Option C (4-8 minutes): Incorrect. 4-8 minutes is for electromagnetic radiation (solar flares), not charged particles (CME). CMEs travel much slower.
Exam Tip
CME travel time = 15 hours to several days. Think 'C'ME = 'C'harged 'M'ass 'E'jection takes 'C'onsiderable time (hours to days). Charged particles travel slower than light, taking 15 hours to several days. Not 28 days (rotation), not 4-8 minutes (radiation) - hours to days.
Memory Aid
CME travel time = 15 hours to several days. Think 'C'ME = 'C'harged 'M'ass 'E'jection takes 'C'onsiderable time. Charged particles travel slower than light, taking 15 hours to several days to reach Earth. Much slower than electromagnetic radiation.
Real-World Example
A coronal mass ejection occurs. The cloud of charged particles travels from the Sun to Earth, taking 1-3 days typically (15 hours to several days). When it arrives, it can cause geomagnetic storms that disrupt HF propagation. This is much slower than solar flare radiation, which takes only 8 minutes (speed of light).
Source & Coverage
Question Pool: 2023-2027 Question Pool
Subelement: G3A
Reference: 2023-2027 Question Pool · G3 - Radio Wave Propagation
Key Concepts
Verified Content
Question from the official FCC General Class pool. Explanation reviewed by licensed amateur radio operators and mapped to the G3A topic.