A \"pulse oximeter\" operates by using light and a photocell to measure oxygen s

Question

A "pulse oximeter" operates by using light and a photocell to measure oxygen saturation in arterial blood. The transmission of light energy as it passes through a solution of light-absorbing molecules is described by the Beer-Lambert law, given below, which gives the decrease in intensity I in terms of the distance L the light has traveled through a fluid with a concentration C of the light-absorbing molecule.
I = I010-eCL or log10(I / I0) = -eCL
The quantity e is called the extinction coefficient, and its value depends on the frequency of the light. (It has units of m2/mol.) Assume the extinction coefficient for 660-nm light passing through a solution of oxygenated hemoglobin is identical to the coefficient for 940-nm light passing through deoxygenated hemoglobin. Also assume also that 940-nm light has zero absorption (e = 0) in oxygenated hemoglobin and 660 nm light has zero absorption in deoxygenated hemoglobin. If 30% of the energy of the red source and 79% of the infrared energy is transmitted through the blood, what is the fraction of hemoglobin that is oxygenated?

%???

Explanation / Answer

Here's your answer. Im doing my homework last minute too :) http://www.cramster.com/answers-mar-09/physics/completely-lost-pulse-oximeter-operates-light-photocell_530317.aspx

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