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5 (a) State one medical use for optical fibres - Edexcel - GCSE Physics - Question 5 - 2017 - Paper 1
Question 5
5 (a) State one medical use for optical fibres. (b) Light is shown down an optical fibre as shown. The intensity of the light coming out of the fibre is 5.0 W/m². ... show full transcript
Worked Solution & Example Answer:5 (a) State one medical use for optical fibres - Edexcel - GCSE Physics - Question 5 - 2017 - Paper 1
Step 1
Step 2
(i) Calculate the intensity of the light as it enters the fibre.
Answer
The intensity at the end of the fibre is 5.0 W/m². Since 1% of the intensity is lost, we calculate the intensity entering the fibre as follows:
1% of 5.0 W/m² is given by: ext{Loss} = 5.0 imes rac{1}{100} = 0.05 ext{ W/m}²
Thus, the intensity entering the fibre is:
Step 3
(ii) Calculation steps for intensity considering the loss.
Answer
To find the power before the intensity loss:
Let it be denoted as and area (for simplicity). Using the relation: Then:
Now, applying the intensity loss: I_{in} = rac{5.0 ext{ W}}{6.2 imes 10^{-7}} Evaluating this gives: Thus, the intensity of the light as it enters the fibre is approximately .