Deep Dive: G3C11
The correct answer is D: The D region. The ionospheric region that is the most absorbent of signals below 10 MHz during daylight hours is the D region. D region is ionized by sunlight, creating strong absorption that affects lower frequencies. For amateur radio operators, this explains why lower bands (160m, 80m, 40m) work better at night. Understanding this helps explain day/night propagation differences.
Why Other Answers Are Wrong
Option A (F2 region): Incorrect. F2 region reflects signals, it doesn't absorb them. F2 is for reflection, not absorption. Option B (F1 region): Incorrect. F1 region reflects signals, it doesn't absorb them. F1 is for reflection, not absorption. Option C (E region): Incorrect. E region reflects signals, it doesn't absorb them. E region is for reflection, not absorption.
Exam Tip
Most absorbent below 10 MHz during day = D region. Think 'D' region = 'D'aytime 'D'isrupts (absorbs). D region is ionized by sunlight, creating strong absorption for lower frequencies. F2, F1, and E reflect - only D absorbs significantly.
Memory Aid
Most absorbent below 10 MHz during day = D region. Think 'D' region = 'D'aytime 'D'isrupts. D region is ionized by sunlight, creating strong absorption for lower frequencies. Only D region significantly absorbs - others reflect.
Real-World Example
You try to operate on 80 meters during the day. The D region is strongly ionized by sunlight, creating heavy absorption that weakens or blocks your signal. At night, the D region de-ionizes, absorption decreases, and 80 meters works much better. D region is the primary absorber of lower frequencies during daylight.
Source & Coverage
Question Pool: 2023-2027 Question Pool
Subelement: G3C
Reference: 2023-2027 Question Pool · G3 - Radio Wave Propagation
Key Concepts
Official Pool Source
Question text and answer key are synchronized with the current NCVEC General Class pool and mapped to the G3C topic.