Advanced Qualification · A-001 Advanced theory · A-001-003-006
What is the resonant frequency of a series RLC circuit, if R is 47 ohms, L is 4 microhenrys and C is 20 picofarads?
- A 19.9 kHz
- B 17.8 kHz
- C 17.8 MHz
- D 19.9 MHz
Correct answer: C — 17.8 MHz. From the official ISED question bank, verified word for word.
Why
The resonant frequency is 17.8 MHz because the formula depends only on the inductor and capacitor values, ignoring the resistance. The full explanation — and one for every question — is in Pro.
Practise this section
Advanced theory: time constants, reactance, impedance, resonance, Q, and the mathematics behind tuned circuits.