Advanced Qualification · A-001 Advanced theory · A-001-004-004
What is the resonant frequency of a parallel RLC circuit if R is 4.7 kilohms, L is 2 microhenrys and C is 30 picofarads?
- A 20.5 kHz
- B 20.5 MHz
- C 2.65 MHz
- D 2.65 kHz
Correct answer: B — 20.5 MHz. From the official ISED question bank, verified word for word.
Why
The resonant frequency depends only on the inductor and capacitor values, not the resistor, so plugging 2 microhenrys and 30 picofarads into the standard formula yields 20.5 MHz. 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.