Reactance and resonance
Inductors and capacitors oppose alternating current by an amount that depends on frequency. Where the two reactances are equal, a circuit is resonant.
- Inductive reactance, XL = 2πfL
- 223.1 Ω
- Capacitive reactance, XC = 1 / 2πfC
- 224.2 Ω
- Resonant frequency of L and C
- 7.1176 MHz
At resonance XL equals XC. Below resonance the capacitor dominates; above it the inductor does.
How it works
- XL = 2πfL and XC = 1 / (2πfC), both in ohms.
- Resonant frequency f = 1 / (2π√(LC)).
Learn more: Electronics basics
Sources: Radio Mathematics (ARRL Handbook supplement) (ARRL); Summary of Class 25: Undriven LRC Circuits (8.02T) (MIT OpenCourseWare)
Practice the exam questions: G5 Electrical Principles (General), E5 Electrical Principles (Amateur Extra)