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Question 18M.3.SL.TZ2.10b.ii

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Date May 2018 Marks available [Maximum mark: 2] Reference code 18M.3.SL.TZ2.10b.ii
Level SL Paper 3 Time zone TZ2
Command term Determine Question number b.ii Adapted from N/A
b.ii.
[Maximum mark: 2]
18M.3.SL.TZ2.10b.ii

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.

(b.ii)

An amplifier can increase the power of the signal by 12 dB. Determine the minimum number of amplifiers required.

[2]

Markscheme

185 × 0.200 = 37 loss over length of cable

« 37 − 23 12 = 1.17» so two amplifiers are sufficient

 

[2 marks]

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