A-LevelPhysicsCapacitanceMay/June 2020Paper 5 Q215 Marks
A student investigates the discharge of a capacitor through a resistor using the circuit shown in Fig. 2.1. [Figure 2.1] The student initially closes the switch and charges the capacitor. The switch is then opened and a stop-watch is started. The capacitor discharges through the resistor. At time t the potential difference V across the capacitor is measured. It is suggested that V and t are related by the equation V = (Q₀/C)e^(-t/RC) where Q₀ is the charge of the fully charged capacitor, C is the capacitance of the capacitor and R is the resistance of the resistor.
📋 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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