Which of the following is opposition to the flow of alternating current in a capacitor?
The correct answer is C: Reactance. The opposition to the flow of alternating current in a capacitor is reactance. Capacitive reactance (XC) is the opposition that capacitors present to AC current. For amateur radio operators, this is a fundamental circuit concept. Understanding this helps when working with capacitors.
Exam Tip
Capacitor AC opposition = reactance. Think 'C'apacitor = 'C'apacitive 'R'eactance. Capacitors present reactance (specifically capacitive reactance XC) to AC current. Not conductance, reluctance, or admittance - just reactance.
Memory Aid
"Capacitor AC opposition = reactance. Think 'C'apacitor = 'C'apacitive 'R'eactance. Capacitors present reactance (XC) to AC current. Frequency-dependent opposition to AC."
Real-World Application
A capacitor in an AC circuit presents capacitive reactance (XC = 1/(2πfC)), which opposes AC current flow. The reactance decreases with frequency - higher frequency means less opposition. This is the opposition that capacitors present to AC.
Key Concepts
Why Other Options Are Wrong
Option A (Conductance): Incorrect. Conductance is the inverse of resistance (1/R), not the opposition in a capacitor. Conductance isn't for capacitors.
Option B (Reluctance): Incorrect. Reluctance is a magnetic circuit term, not an electrical circuit term for AC opposition. Reluctance is for magnetic circuits.
Option D (Admittance): Incorrect. Admittance is the inverse of impedance (1/Z), not the opposition in a capacitor. Admittance isn't the opposition.
题目解析
The correct answer is C: Reactance. The opposition to the flow of alternating current in a capacitor is reactance. Capacitive reactance (XC) is the opposition that capacitors present to AC current. For amateur radio operators, this is a fundamental circuit concept. Understanding this helps when working with capacitors.
考试技巧
Capacitor AC opposition = reactance. Think 'C'apacitor = 'C'apacitive 'R'eactance. Capacitors present reactance (specifically capacitive reactance XC) to AC current. Not conductance, reluctance, or admittance - just reactance.
记忆口诀
Capacitor AC opposition = reactance. Think 'C'apacitor = 'C'apacitive 'R'eactance. Capacitors present reactance (XC) to AC current. Frequency-dependent opposition to AC.
实际应用示例
A capacitor in an AC circuit presents capacitive reactance (XC = 1/(2πfC)), which opposes AC current flow. The reactance decreases with frequency - higher frequency means less opposition. This is the opposition that capacitors present to AC.
错误选项分析
Option A (Conductance): Incorrect. Conductance is the inverse of resistance (1/R), not the opposition in a capacitor. Conductance isn't for capacitors. Option B (Reluctance): Incorrect. Reluctance is a magnetic circuit term, not an electrical circuit term for AC opposition. Reluctance is for magnetic circuits. Option D (Admittance): Incorrect. Admittance is the inverse of impedance (1/Z), not the opposition in a capacitor. Admittance isn't the opposition.
知识点
Capacitor, Reactance, Capacitive reactance, AC opposition
Verified Content
Question from official FCC General Class question pool. Explanation reviewed by licensed amateur radio operators.