What does the K-index measure?
The correct answer is B: The short-term stability of Earth's geomagnetic field. The K-index measures the short-term stability of Earth's geomagnetic field. K-index indicates geomagnetic activity on a scale of 0-9, with higher values indicating more disturbance. For amateur radio operators, K-index helps assess propagation conditions. Understanding this helps when checking propagation forecasts.
Exam Tip
K-index = short-term stability of Earth's geomagnetic field. Think 'K'-index = 'K'eeps track of 'E'arth's 'G'eomagnetic field. Measures short-term stability of Earth's geomagnetic field (0-9 scale). Not sunspots, not Sun's field, not solar flux - just Earth's geomagnetic field.
Memory Aid
"K-index = short-term stability of Earth's geomagnetic field. Think 'K'-index = 'K'eeps track of Earth's geomagnetic field. Measures short-term stability (0-9 scale). Low K = quiet, high K = disturbed. Key propagation indicator."
Real-World Application
You check the K-index - it's 3 (quiet conditions). K-index measures the short-term stability of Earth's geomagnetic field on a scale of 0-9. Low K (0-2) means quiet conditions, high K (5+) means disturbed conditions that can disrupt HF propagation. K-index helps assess geomagnetic activity.
Key Concepts
Why Other Options Are Wrong
Option A: Incorrect. K-index doesn't measure sunspot position - that's not what it measures. K-index measures geomagnetic field stability.
Option C: Incorrect. K-index doesn't measure the Sun's magnetic field - it measures Earth's geomagnetic field, not the Sun's.
Option D: Incorrect. K-index doesn't measure solar radio flux - that's the solar flux index. K-index measures geomagnetic field stability.
题目解析
The correct answer is B: The short-term stability of Earth's geomagnetic field. The K-index measures the short-term stability of Earth's geomagnetic field. K-index indicates geomagnetic activity on a scale of 0-9, with higher values indicating more disturbance. For amateur radio operators, K-index helps assess propagation conditions. Understanding this helps when checking propagation forecasts.
考试技巧
K-index = short-term stability of Earth's geomagnetic field. Think 'K'-index = 'K'eeps track of 'E'arth's 'G'eomagnetic field. Measures short-term stability of Earth's geomagnetic field (0-9 scale). Not sunspots, not Sun's field, not solar flux - just Earth's geomagnetic field.
记忆口诀
K-index = short-term stability of Earth's geomagnetic field. Think 'K'-index = 'K'eeps track of Earth's geomagnetic field. Measures short-term stability (0-9 scale). Low K = quiet, high K = disturbed. Key propagation indicator.
实际应用示例
You check the K-index - it's 3 (quiet conditions). K-index measures the short-term stability of Earth's geomagnetic field on a scale of 0-9. Low K (0-2) means quiet conditions, high K (5+) means disturbed conditions that can disrupt HF propagation. K-index helps assess geomagnetic activity.
错误选项分析
Option A: Incorrect. K-index doesn't measure sunspot position - that's not what it measures. K-index measures geomagnetic field stability. Option C: Incorrect. K-index doesn't measure the Sun's magnetic field - it measures Earth's geomagnetic field, not the Sun's. Option D: Incorrect. K-index doesn't measure solar radio flux - that's the solar flux index. K-index measures geomagnetic field stability.
知识点
K-index, Geomagnetic field, Short-term stability, Propagation indicator
Verified Content
Question from official FCC General Class question pool. Explanation reviewed by licensed amateur radio operators.