What is the relationship between the AC current through a capacitor and the voltage across a capacitor?
The correct answer is D: Current leads voltage by 90 degrees. What is the relationship between the AC current through a capacitor and the voltage across a capacitor is that current leads voltage by 90 degrees. In a capacitor, current leads voltage by 90°. For amateur radio operators, this is important for circuit theory. Understanding this helps when working with capacitors.
Exam Tip
Capacitor AC relationship = current leads voltage by 90 degrees. Think 'C'apacitor = 'C'urrent 'L'eads. In a capacitor, current leads voltage by 90°. Not in phase, not 180°, not voltage leading - just current leads by 90°.
Memory Aid
"Capacitor AC relationship = current leads voltage by 90 degrees. Think 'C'apacitor = 'C'urrent 'L'eads. In a capacitor, current leads voltage by 90°. Important for circuit theory."
Real-World Application
AC current through a capacitor and voltage across a capacitor: The current leads the voltage by 90 degrees. This is because the capacitor's current responds immediately to voltage changes, while the voltage builds up. This is the relationship - current leads voltage by 90°.
Key Concepts
Why Other Options Are Wrong
Option A: Incorrect. Voltage and current in phase isn't correct - in a capacitor, current leads voltage by 90°. In phase is wrong.
Option B: Incorrect. Voltage and current 180 degrees out of phase isn't correct - in a capacitor, current leads voltage by 90°. 180° is wrong.
Option C: Incorrect. Voltage leads current by 90 degrees isn't correct - in a capacitor, current leads voltage by 90°. Voltage leading is wrong.
题目解析
The correct answer is D: Current leads voltage by 90 degrees. What is the relationship between the AC current through a capacitor and the voltage across a capacitor is that current leads voltage by 90 degrees. In a capacitor, current leads voltage by 90°. For amateur radio operators, this is important for circuit theory. Understanding this helps when working with capacitors.
考试技巧
Capacitor AC relationship = current leads voltage by 90 degrees. Think 'C'apacitor = 'C'urrent 'L'eads. In a capacitor, current leads voltage by 90°. Not in phase, not 180°, not voltage leading - just current leads by 90°.
记忆口诀
Capacitor AC relationship = current leads voltage by 90 degrees. Think 'C'apacitor = 'C'urrent 'L'eads. In a capacitor, current leads voltage by 90°. Important for circuit theory.
实际应用示例
AC current through a capacitor and voltage across a capacitor: The current leads the voltage by 90 degrees. This is because the capacitor's current responds immediately to voltage changes, while the voltage builds up. This is the relationship - current leads voltage by 90°.
错误选项分析
Option A: Incorrect. Voltage and current in phase isn't correct - in a capacitor, current leads voltage by 90°. In phase is wrong. Option B: Incorrect. Voltage and current 180 degrees out of phase isn't correct - in a capacitor, current leads voltage by 90°. 180° is wrong. Option C: Incorrect. Voltage leads current by 90 degrees isn't correct - in a capacitor, current leads voltage by 90°. Voltage leading is wrong.
知识点
AC current through capacitor, Voltage across capacitor, Current leads voltage, 90 degrees
Verified Content
Question from official FCC Extra Class question pool. Explanation reviewed by licensed amateur radio operators.