A-LevelPhysicsQuantum physicsFeb/Mar 2018Paper 4 Q117 Marks
Some electron energy bands in a solid are shown in [Figure 11.1]. The width of the forbidden band and the number density of charge carriers occupying each band depends on the nature of the solid. Use band theory to explain why (a) the resistance of a metal at room temperature increases gradually with temperature, (b) the resistance, at constant temperature, of a light-dependent resistor (LDR) decreases with increasing light intensity.
📋 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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