A-LevelPhysicsD.C. circuitsOct/Nov 2011Paper 1 Q351 Mark
A power supply of electromotive force (e.m.f.) 12 V and internal resistance 2 Ω is connected in series with a load resistor. The value of the load resistor is varied from 0.5 Ω to 4 Ω. Which graph shows how the power P dissipated in the load resistor varies with the resistance of the load resistor? [Figure 35.1]
Agraph showing power peaking at load resistance 2 Ω
Bgraph showing power at a minimum at load resistance 2 Ω
Cgraph showing power increasing linearly with load resistance
Dgraph showing power increasing with load resistance, curving upwards
✓ Correct Answer
The correct answer is A: graph showing power peaking at load resistance 2 Ω
📋 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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