Deep Dive: E5A01
The correct answer is A: Resonance. What can cause the voltage across reactances in a series RLC circuit to be higher than the voltage applied to the entire circuit is resonance. At resonance, reactances can have higher voltages than the source due to Q multiplication. For amateur radio operators, this is important for circuit theory. Understanding this helps when working with resonant circuits.
Why Other Answers Are Wrong
Option B (Capacitance): Incorrect. Capacitance alone doesn't cause higher voltage - resonance does. Capacitance isn't the cause. Option C (Low quality factor Q): Incorrect. Low Q doesn't cause higher voltage - resonance with high Q does. Low Q is wrong. Option D (Resistance): Incorrect. Resistance doesn't cause higher voltage - resonance does. Resistance isn't the cause.
Exam Tip
Voltage across reactances higher than applied = resonance. Think 'R'esonance = 'R'eactance 'V'oltage 'E'nhancement. At resonance, reactances can have higher voltages than the source due to Q multiplication. Not capacitance, not low Q, not resistance - just resonance.
Memory Aid
Voltage across reactances higher than applied = resonance. Think 'R'esonance = 'H'igher 'V'oltage. At resonance, reactances can have higher voltages than the source due to Q multiplication. Important for circuit theory.
Real-World Example
A series RLC circuit at resonance: The voltage across the reactances (inductor or capacitor) can be higher than the voltage applied to the entire circuit. This is due to the Q (quality factor) of the circuit - the reactance voltage is Q times the source voltage. This is what causes it - resonance.
Source & Coverage
Question Pool: 2024-2028 Question Pool
Subelement: E5A
Reference: 2024-2028 Question Pool · E5 - Electrical Principles
Key Concepts
Verified Content
Question from the official FCC Extra Class pool. Explanation reviewed by licensed amateur radio operators and mapped to the E5A topic.