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Beer-Lambert law — FRCA Primary MCQ

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EasyPhysicsBeer-Lambert lawFRCA Primary

A pulse oximeter uses red and infrared light absorption to estimate saturation. What is the most likely explanation?

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Correct answer: BBeer-Lambert law

Absorbance relates to concentration and path length. Lower gas density reduces turbulent resistance is less appropriate because it would fit a different clinical clue or a separate anaesthetic problem. Fick's law is less appropriate because it would fit a different clinical clue or a separate anaesthetic problem. Laplace's law is less appropriate because it would fit a different clinical clue or a separate anaesthetic problem. Charles' law 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