Oxygenated hemoglobin absorbs weakly in the red (hence its red color) and strongly in the near infrared, whereas deoxygenated hemoglobin has

Question

Oxygenated hemoglobin absorbs weakly in the red (hence its red color) and strongly in the near infrared, whereas deoxygenated hemoglobin has the opposite absorption. This fact is used in a “pulse oximeter” to measure oxygen saturation in arterial blood. The device clips onto the end of a person’s finger and has two light-emitting diodes—a red (653 nm) and an infrared (935 nm)—and a photocell that detects the amount of light transmitted through the finger at each wavelength.

If 64% of the energy of the red source is absorbed in the blood, by what factor does the amplitude of the electromagnetic wave change?

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Khánh Gia 2 months 2021-08-17T01:59:22+00:00 1 Answers 7 views 0

Answers ( )

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    2021-08-17T02:00:50+00:00

    Answer:

    0.6

    Explanation:

    I_i = Initial intensity

    E denotes amplitude

    Final intensity is

    I_f=(1-0.64)I_i=0.36I_i

    We have the relation

    \dfrac{E_i^2}{E_f^2}=\dfrac{I_i}{I_f}\\\Rightarrow \dfrac{E_i^2}{E_f^2}=\dfrac{I_f}{0.36I_i}\\\Rightarrow \dfrac{E_i^2}{E_f^2}=\dfrac{1}{0.36}\\\Rightarrow \dfrac{E_f^2}{E_i^2}=0.36\\\Rightarrow E_f^2=0.36E_i^2\\\Rightarrow E_f=0.6E_i

    The amplitude changes by a factor of 0.6

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