Question

In a series resonance type BPF, C = 1.8 pf, L = 25 mH, RF = 52 Ω and RL = 9 kΩ. The Resonant frequency f is __________

(a) 75.1 kHz

(b) 751 kHz

(c) 575 kHz

(d) 57.5 kHz

The question was posed to me in a national level competition.

I want to ask this question from Problems of Series Resonance Involving Quality Factor topic in section Resonance & Magnetically Coupled Circuit of Network Theory

Answer 1

The correct answer is (b) 751 kHz

For explanation: f = \(\frac{1}{2π\sqrt{LC}} = \frac{1}{2π\sqrt{0.025×1.8×10^{-12}}}\)

= \(\frac{1}{2π} × \frac{10^6}{\sqrt{0.45}}\)

= \(\frac{1}{2π} × \frac{10^6}{0.67}\)

= 751000

∴ f = 751 kHz.