What is reactance?
The correct answer is B: Opposition to the flow of alternating current caused by capacitance or inductance. Reactance is opposition to the flow of alternating current caused by capacitance or inductance. Reactance is the AC equivalent of resistance, but it's frequency-dependent and caused by capacitors or inductors. For amateur radio operators, this is a fundamental circuit concept. Understanding this helps when working with AC circuits.
Exam Tip
Reactance = opposition to AC caused by capacitance or inductance. Think 'R'eactance = 'R'esistance to 'A'C from 'C'apacitance/'I'nductance. Opposition to alternating current caused by capacitors or inductors. Not DC, not reinforcement - just AC opposition from C or L.
Memory Aid
"Reactance = opposition to AC caused by capacitance or inductance. Think 'R'eactance = 'R'esistance to 'A'C. Opposition to alternating current caused by capacitors or inductors. Frequency-dependent opposition to AC."
Real-World Application
A capacitor or inductor in an AC circuit presents reactance - opposition to AC current flow. Unlike resistance (which opposes both AC and DC), reactance only opposes AC and is frequency-dependent. Capacitive reactance decreases with frequency, inductive reactance increases with frequency.
Key Concepts
Why Other Options Are Wrong
Option A: Incorrect. Reactance isn't opposition to DC caused by resistance - that's just resistance. Reactance is for AC, not DC.
Option C: Incorrect. Reactance isn't reinforcement of DC flow - reactance opposes AC, it doesn't reinforce anything. Reinforcement isn't the concept.
Option D: Incorrect. Reactance isn't reinforcement of AC flow - reactance opposes AC flow, it doesn't reinforce it. Opposition is the key concept.
题目解析
The correct answer is B: Opposition to the flow of alternating current caused by capacitance or inductance. Reactance is opposition to the flow of alternating current caused by capacitance or inductance. Reactance is the AC equivalent of resistance, but it's frequency-dependent and caused by capacitors or inductors. For amateur radio operators, this is a fundamental circuit concept. Understanding this helps when working with AC circuits.
考试技巧
Reactance = opposition to AC caused by capacitance or inductance. Think 'R'eactance = 'R'esistance to 'A'C from 'C'apacitance/'I'nductance. Opposition to alternating current caused by capacitors or inductors. Not DC, not reinforcement - just AC opposition from C or L.
记忆口诀
Reactance = opposition to AC caused by capacitance or inductance. Think 'R'eactance = 'R'esistance to 'A'C. Opposition to alternating current caused by capacitors or inductors. Frequency-dependent opposition to AC.
实际应用示例
A capacitor or inductor in an AC circuit presents reactance - opposition to AC current flow. Unlike resistance (which opposes both AC and DC), reactance only opposes AC and is frequency-dependent. Capacitive reactance decreases with frequency, inductive reactance increases with frequency.
错误选项分析
Option A: Incorrect. Reactance isn't opposition to DC caused by resistance - that's just resistance. Reactance is for AC, not DC. Option C: Incorrect. Reactance isn't reinforcement of DC flow - reactance opposes AC, it doesn't reinforce anything. Reinforcement isn't the concept. Option D: Incorrect. Reactance isn't reinforcement of AC flow - reactance opposes AC flow, it doesn't reinforce it. Opposition is the key concept.
知识点
Reactance, Opposition to AC, Capacitance, Inductance
Verified Content
Question from official FCC General Class question pool. Explanation reviewed by licensed amateur radio operators.