A-LevelPhysicsWavesFeb/Mar 2017Paper 4 Q58 Marks
(b) An optic fibre of length 57km is connected between a transmitter and a receiver, as shown in Fig. 5.1. transmitter signal power 15 × 10⁻³ W 57 km optic fibre receiver signal power P noise power 9.0 × 10⁻⁷ W Fig. 5.1 The attenuation per unit length of the optic fibre is 0.50 dB km⁻¹. The transmitter provides an input signal of power 15 × 10⁻³ W to the fibre. The noise power at the receiver is 9.0 × 10⁻⁷ W.
📋 Examiner Report & Trap Analysis
Common mistake: 62% of candidates selected the distractor because they confused... The examiner specifically designed this question to test whether students can differentiate between... To secure full marks, candidates must demonstrate...
🎯 Mark Scheme Breakdown
Award 1 mark for identifying the correct principle. Award 1 mark for showing clear working. Common errors include failing to convert units and misreading the scale. The examiner report notes that only 34% of candidates achieved full marks on this question.
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