*Question G3B09:
What is the approximate maximum distance along the Earth’s surface normally covered in one hop using the F2 region?*  

*Correct Answer is  C: 2,500 miles*  

### AI Response: (may contain errors)  

The correct answer to the question about the maximum distance covered in one hop using the F2 region is 2,500 miles. Here's the explanation:

1. **Why the correct answer is correct:**
   - The F2 region is the highest layer of the ionosphere, typically found at altitudes of about 200 to 400 kilometers (approximately 124 to 248 miles). It reflects high-frequency (HF) radio waves, allowing for long-distance communication.
   - The approximate maximum distance for a single hop in the F2 region is around 2,500 miles. This is due to the ionospheric conditions and the frequency of the signals being used, which can effectively reflect off the F2 layer and cover vast distances.

2. **Why the other choices are incorrect:**
   - **A: 180 miles**: This distance is too short for the F2 region. It may be more applicable to lower frequency bands or other propagation modes.
   - **B: 1,200 miles**: While this distance is more plausible than 180 miles, it still underestimates the potential range of the F2 region, which can reach much farther.
   - **D: 12,000 miles**: This distance exceeds the typical range for a single hop in the F2 region. While multiple hops can cover greater distances, a single hop is generally limited to around 2,500 miles.

3. **Useful formulas or rules of thumb:**
   - A common rule of thumb for estimating the maximum distance for HF propagation is:
     $$ D \approx 2.5 \times \sqrt{h} $$
     where:
     - $D$ = distance in miles
     - $h$ = height of the ionospheric layer in kilometers
   - For the F2 region, if we take an average height of about 300 km:
     $$ D \approx 2.5 \times \sqrt{300} \approx 2.5 \times 17.32 \approx 43.3 \text{ miles} $$
   - However, this formula is more of a guideline, and actual distances can vary based on frequency, time of day, and solar activity.

In summary, the F2 region can effectively support communication over distances of approximately 2,500 miles in a single hop, making it the correct answer for this question.