How does an inductor react to AC?
The correct answer is D: As the frequency of the applied AC increases, the reactance increases. How an inductor reacts to AC is that as the frequency of the applied AC increases, the reactance increases. Inductive reactance XL = 2πfL, so it's directly proportional to frequency. For amateur radio operators, this is a fundamental relationship. Understanding this helps when working with inductors.
Exam Tip
Inductor reactance = increases with frequency. Think 'I'nductor 'R'eactance = 'I'ncreases 'R'apidly with frequency. XL = 2πfL, so reactance is directly proportional to frequency. Not decreases, not amplitude-dependent - just increases with frequency.
Memory Aid
"Inductor reactance = increases with frequency. Think 'I'nductor 'R'eactance = 'I'ncreases 'R'apidly. XL = 2πfL, so reactance is directly proportional to frequency. Higher frequency = higher reactance."
Real-World Application
An inductor with 10 µH inductance. At 1 MHz, reactance is about 63 ohms. At 10 MHz, reactance is about 630 ohms. As frequency increases, inductive reactance increases proportionally. This is why inductors block high frequencies (high reactance).
Key Concepts
Why Other Options Are Wrong
Option A: Incorrect. Inductive reactance doesn't decrease with frequency - it increases. XL = 2πfL, so higher frequency means higher reactance.
Option B: Incorrect. Reactance doesn't depend on amplitude - it depends on frequency and inductance. Amplitude doesn't affect reactance.
Option C: Incorrect. Reactance doesn't decrease with amplitude - it doesn't depend on amplitude at all. Amplitude doesn't affect reactance.
题目解析
The correct answer is D: As the frequency of the applied AC increases, the reactance increases. How an inductor reacts to AC is that as the frequency of the applied AC increases, the reactance increases. Inductive reactance XL = 2πfL, so it's directly proportional to frequency. For amateur radio operators, this is a fundamental relationship. Understanding this helps when working with inductors.
考试技巧
Inductor reactance = increases with frequency. Think 'I'nductor 'R'eactance = 'I'ncreases 'R'apidly with frequency. XL = 2πfL, so reactance is directly proportional to frequency. Not decreases, not amplitude-dependent - just increases with frequency.
记忆口诀
Inductor reactance = increases with frequency. Think 'I'nductor 'R'eactance = 'I'ncreases 'R'apidly. XL = 2πfL, so reactance is directly proportional to frequency. Higher frequency = higher reactance.
实际应用示例
An inductor with 10 µH inductance. At 1 MHz, reactance is about 63 ohms. At 10 MHz, reactance is about 630 ohms. As frequency increases, inductive reactance increases proportionally. This is why inductors block high frequencies (high reactance).
错误选项分析
Option A: Incorrect. Inductive reactance doesn't decrease with frequency - it increases. XL = 2πfL, so higher frequency means higher reactance. Option B: Incorrect. Reactance doesn't depend on amplitude - it depends on frequency and inductance. Amplitude doesn't affect reactance. Option C: Incorrect. Reactance doesn't decrease with amplitude - it doesn't depend on amplitude at all. Amplitude doesn't affect reactance.
知识点
Inductor, Reactance, Frequency increase, Inductive reactance
Verified Content
Question from official FCC General Class question pool. Explanation reviewed by licensed amateur radio operators.