Rotameter — FRCA Primary MCQ

Correct answer: C — Top of the bobbin gives calibrated flow

A variable-area flowmeter is read from the top of the bobbin when calibrated for that bobbin and gas. Hypoxic guard is less appropriate because it would fit a different clinical clue or a separate anaesthetic problem. Hydrostatic levelling error is less appropriate because it would fit a different clinical clue or a separate anaesthetic problem. Ferromagnetic projectile risk is less appropriate because it would fit a different clinical clue or a separate anaesthetic problem. Doppler frequency shift is less appropriate because it would fit a different clinical clue or a separate anaesthetic problem. In Primary FRCA physics and measurement, the safest answer is the one that follows the underlying physical principle and the limitations of the device.

Reference: Davis and Kenny Basic Physics and Measurement in Anaesthesia; RCoA Primary FRCA syllabus