A-LevelPhysicsD.C. circuitsMay/June 2018Paper 5 Q215 Marks
A student is investigating the charging of a capacitor. A circuit is set up as shown in Fig. 2.1. [Figure 2.1] The capacitor is initially discharged. A resistor of resistance R is connected between P and Q. When the switch is closed, the time t for the voltmeter reading to increase to a specific value V is measured. The capacitor is then discharged. The experiment is repeated with a different number n of resistors each of resistance R connected in series between P and Q. It is suggested that t and n are related by the equation 1 - V/E = e^(-t/(nRC)) where E is the electromotive force (e.m.f.) of the power supply and C is the capacitance of the capacitor.
📋 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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