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Pulse oximeters and ECGs are used to monitor the blood oxygen levels and heart activity of a patient - Edexcel - GCSE Physics - Question 6 - 2015 - Paper 1
Question 6
Pulse oximeters and ECGs are used to monitor the blood oxygen levels and heart activity of a patient. (a) Pulse oximeters are often attached to a finger. They use b... show full transcript
Worked Solution & Example Answer:Pulse oximeters and ECGs are used to monitor the blood oxygen levels and heart activity of a patient - Edexcel - GCSE Physics - Question 6 - 2015 - Paper 1
Step 1
Identify the correct statement about red light and infrared radiation
Answer
From the given options:
- A states that infrared radiation is ionising while red light is not, which is true.
- B suggests that red light can travel through a finger while infrared cannot, which is incorrect.
- C claims red light has a shorter wavelength than infrared, which is also incorrect as infrared has a longer wavelength.
- D states that red light is ionising while infrared is not, which is false.
Therefore, the correct answer is A: infrared radiation is ionising, red light is not ionising.
Step 2
Investigate absorption of light
Answer
From the data provided, we can analyze how the intensity of light changes with different thicknesses of absorbers:
- At 0.0 mm, the intensity is 0.23 mW/cm².
- As thickness increases to 7.5 mm, intensity drops to 0.16 mW/cm².
- At 15.0 mm, intensity further decreases to 0.11 mW/cm².
- At 22.5 mm, the intensity is 0.08 mW/cm².
- Finally, at 30.0 mm, the intensity reaches 0.06 mW/cm².
This shows a clear trend that as the thickness of the absorber increases, the intensity of light detected decreases, demonstrating the absorbing power of the plastic sheets.