A-LevelPhysicsD.C. circuitsOct/Nov 2018Paper 5 Q215 Marks
A student is investigating the current in a circuit. The circuit is set up as shown in Fig. 2.1. [Figure 2.1] Resistors, each of resistance R, are connected in parallel between P and Q. The current I is measured. The experiment is repeated for different numbers n of resistors between P and Q. It is suggested that I and n are related by the equation E = I (R/n + r) where E is the electromotive force (e.m.f.) and r is the internal resistance of the power supply.
📋 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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