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Natural Frequency 10x Fundamental — FRCA Primary MCQ

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HardPhysics & Clinical MeasurementNatural Frequency 10x FundamentalFRCA Primary

A patient has a heart rate of 120 min−1, giving a 2 Hz fundamental arterial frequency. Reproduction of the first eight harmonics is required. Which system property is most appropriate?

Educational content. Not a substitute for clinical judgement or local policy.

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Correct answer: D — Natural frequency >16 Hz with damping 0.5–0.7

The best answer is “Natural frequency >16 Hz with damping 0.5–0.7”. Eight harmonics of a 2 Hz fundamental extend to 16 Hz, so the monitoring system should have a natural frequency comfortably above that range and suitable damping. Matching natural frequency to a harmonic promotes resonance. Sampling frequency is a separate digital requirement, and excessive damping attenuates clinically important waveform components.

Reference: Fujiwara et al., Effect of Planecta and ROSE on the frequency characteristics of blood pressure-transducer kits: https://pmc.ncbi.nlm.nih.gov/articles/PMC4621715/