What is the phase relationship between the current through and the voltage across a series resonant circuit at resonance?
The correct answer is C: The voltage and current are in phase. What is the phase relationship between the current through and the voltage across a series resonant circuit at resonance is that the voltage and current are in phase. At resonance, reactances cancel, so voltage and current are in phase. For amateur radio operators, this is important for circuit theory. Understanding this helps when working with resonant circuits.
Exam Tip
Series resonant circuit at resonance = voltage and current in phase. Think 'S'eries 'R'esonance = 'S'ame 'P'hase. At resonance, reactances cancel, so voltage and current are in phase. Not 90° lead, not 90° lag, not 180° - just in phase.
Memory Aid
"Series resonant circuit at resonance = voltage and current in phase. Think 'S'eries 'R'esonance = 'I'n phase. At resonance, reactances cancel, so voltage and current are in phase. Important for circuit theory."
Real-World Application
A series resonant circuit at resonance: The voltage and current are in phase. At resonance, the inductive reactance and capacitive reactance are equal and opposite, so they cancel, leaving only resistance. With pure resistance, voltage and current are in phase. This is the relationship - in phase.
Key Concepts
Why Other Options Are Wrong
Option A: Incorrect. Voltage leads current by 90 degrees isn't correct - at resonance, voltage and current are in phase. 90° lead isn't correct.
Option B: Incorrect. Current leads voltage by 90 degrees isn't correct - at resonance, voltage and current are in phase. 90° lead isn't correct.
Option D: Incorrect. Voltage and current are 180 degrees out of phase isn't correct - at resonance, voltage and current are in phase. 180° out of phase isn't correct.
题目解析
The correct answer is C: The voltage and current are in phase. What is the phase relationship between the current through and the voltage across a series resonant circuit at resonance is that the voltage and current are in phase. At resonance, reactances cancel, so voltage and current are in phase. For amateur radio operators, this is important for circuit theory. Understanding this helps when working with resonant circuits.
考试技巧
Series resonant circuit at resonance = voltage and current in phase. Think 'S'eries 'R'esonance = 'S'ame 'P'hase. At resonance, reactances cancel, so voltage and current are in phase. Not 90° lead, not 90° lag, not 180° - just in phase.
记忆口诀
Series resonant circuit at resonance = voltage and current in phase. Think 'S'eries 'R'esonance = 'I'n phase. At resonance, reactances cancel, so voltage and current are in phase. Important for circuit theory.
实际应用示例
A series resonant circuit at resonance: The voltage and current are in phase. At resonance, the inductive reactance and capacitive reactance are equal and opposite, so they cancel, leaving only resistance. With pure resistance, voltage and current are in phase. This is the relationship - in phase.
错误选项分析
Option A: Incorrect. Voltage leads current by 90 degrees isn't correct - at resonance, voltage and current are in phase. 90° lead isn't correct. Option B: Incorrect. Current leads voltage by 90 degrees isn't correct - at resonance, voltage and current are in phase. 90° lead isn't correct. Option D: Incorrect. Voltage and current are 180 degrees out of phase isn't correct - at resonance, voltage and current are in phase. 180° out of phase isn't correct.
知识点
Phase relationship, Current through, Voltage across, Series resonant circuit, At resonance, In phase
Verified Content
Question from official FCC Extra Class question pool. Explanation reviewed by licensed amateur radio operators.