What is indicated by a rising A-index or K-index?
The correct answer is A: Increasing disturbance of the geomagnetic field. What is indicated by a rising A-index or K-index is increasing disturbance of the geomagnetic field. Higher A/K indices mean more geomagnetic disturbance. For amateur radio operators, this is important for understanding propagation conditions. Understanding this helps when evaluating propagation.
Exam Tip
Rising A/K index = increasing disturbance of geomagnetic field. Think 'R'ising 'A'/'K' = 'R'ising 'A'ctivity/'K'haos. Higher A/K indices mean more geomagnetic disturbance. Not decreasing, not UV radiation, not critical frequency - just increasing geomagnetic disturbance.
Memory Aid
"Rising A/K index = increasing disturbance of geomagnetic field. Think 'R'ising 'A'/'K' = 'I'ncreasing 'D'isturbance. Higher A/K indices mean more geomagnetic disturbance. Important for understanding propagation conditions."
Real-World Application
A rising A-index or K-index: It indicates increasing disturbance of the geomagnetic field. Higher indices mean the Earth's magnetic field is more disturbed, which can affect HF propagation (especially polar paths). This is what rising indices indicate - increasing geomagnetic disturbance.
Key Concepts
Why Other Options Are Wrong
Option B: Incorrect. Decreasing disturbance isn't indicated - rising indices mean increasing disturbance. Decreasing is wrong.
Option C: Incorrect. Higher levels of solar UV radiation isn't what A/K indices measure - they measure geomagnetic disturbance. UV radiation isn't the indication.
Option D: Incorrect. Increase in critical frequency isn't what A/K indices indicate - they indicate geomagnetic disturbance. Critical frequency isn't the indication.
题目解析
The correct answer is A: Increasing disturbance of the geomagnetic field. What is indicated by a rising A-index or K-index is increasing disturbance of the geomagnetic field. Higher A/K indices mean more geomagnetic disturbance. For amateur radio operators, this is important for understanding propagation conditions. Understanding this helps when evaluating propagation.
考试技巧
Rising A/K index = increasing disturbance of geomagnetic field. Think 'R'ising 'A'/'K' = 'R'ising 'A'ctivity/'K'haos. Higher A/K indices mean more geomagnetic disturbance. Not decreasing, not UV radiation, not critical frequency - just increasing geomagnetic disturbance.
记忆口诀
Rising A/K index = increasing disturbance of geomagnetic field. Think 'R'ising 'A'/'K' = 'I'ncreasing 'D'isturbance. Higher A/K indices mean more geomagnetic disturbance. Important for understanding propagation conditions.
实际应用示例
A rising A-index or K-index: It indicates increasing disturbance of the geomagnetic field. Higher indices mean the Earth's magnetic field is more disturbed, which can affect HF propagation (especially polar paths). This is what rising indices indicate - increasing geomagnetic disturbance.
错误选项分析
Option B: Incorrect. Decreasing disturbance isn't indicated - rising indices mean increasing disturbance. Decreasing is wrong. Option C: Incorrect. Higher levels of solar UV radiation isn't what A/K indices measure - they measure geomagnetic disturbance. UV radiation isn't the indication. Option D: Incorrect. Increase in critical frequency isn't what A/K indices indicate - they indicate geomagnetic disturbance. Critical frequency isn't the indication.
知识点
A-index, K-index, Rising, Increasing disturbance
Verified Content
Question from official FCC Extra Class question pool. Explanation reviewed by licensed amateur radio operators.