# Extra Class Worked Example, Question E5A16

Frank Dambach, KK6GPI, asked for a detailed, worked-through example of determining the resonant frequency of an RLC circuit. He chose Extra question E5A16. The question has to do with determining the resonant frequency of a parallel RLC circuit for R=33 ohms, L=50 microhenries, and C=10 picofarads.

The 33 ohm resistor in the question is extraneous information. It’s what in my engineering student days we called “the dimensions of the doorknob,” meaning information that has no bearing on the answer. The frequency of resonance is determined solely by the inductor and the capacitor.

However, if we were determining the Q for the circuit, the resistance enters into the equation. But that’s not the task at hand.

(My apologies for the focus issues early in the video. The camera hunts for something at the center of the scene to focus on.)

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### 2 Responses to Extra Class Worked Example, Question E5A16

1. Dave says:

You’re welcome!

2. Frank Dambach says:

Thanks sooo much Dave! I figured out how to do this on a scientific calculator but had forgotten completely how to treat the exponents when squaring and moving from denominator to numerator. This was a big help and I hope other followers will agree. Thanks again!