Extra exam question E5A02
Subelement E5, ELECTRICAL PRINCIPLES· Group E5A
What is the resonant frequency of an RLC circuit if R is 22 ohms, L is 50 microhenries, and C is 40 picofarads?
- A.44.72 MHz
- B.22.36 MHz
- C.3.56 MHz (correct answer)
- D.1.78 MHz
WhyAn RLC circuit with 50 microhenries of inductance and 40 picofarads of capacitance resonates at about 3.56 MHz. Resonant frequency is found from f equals 1 divided by 2 pi times the square root of L times C, and resistance doesn't enter into an ideal LC resonance calculation at all: the square root of 50 microhenries times 40 picofarads works out to about 4.47 times 10^-8, and 1 divided by 2 pi times that figure gives approximately 3.56 MHz, answer C. The other listed frequencies come from misapplying the formula or mixing up the exponents on L and C.
Published 2026-08-28 · Last updated 2026-08-28 · Question text is verbatim from the 2024-2028 NCVEC Element 4 pool (public domain); the explanation above is original writing, see our methodology.
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