DP Physics (last assessment 2024)

Question 18M.3.SL.TZ2.b.i

Date	May 2018	Marks available	[Maximum mark: 2]	Reference code	18M.3.SL.TZ2.b.i
Level	SL	Paper	3	Time zone	TZ2
Command term	Calculate	Question number	b.i	Adapted from	N/A

b.i.

[Maximum mark: 2]

18M.3.SL.TZ2.b.i

An optic fibre of length 185 km has an attenuation of 0.200 dB km^–1. The input power to the cable is 400.0 μW. The output power from the cable must not fall below 2.0 μW.

Calculate the maximum attenuation allowed for the signal.

[2]

Markscheme

attenuation = «10 log $\frac{I}{{{I_0}}}$ » = 10 log $\frac{{2.0 \times {{10}^{ - 6}}}}{{400 \times {{10}^{ - 6}}}}$

attenuation = «–»23 «dB»

Accept 10 log $\frac{{400}}{{2.0}}$ for first marking point

[2 marks]

Syllabus sections

Option C: Imaging

Option C: Imaging » Option C: Imaging (Core topics) » C.3 – Fibre optics

Option C: Imaging » Option C: Imaging (Core topics)

Question 18M.3.SL.TZ2.b.i

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