A-LevelPhysicsD.C. circuitsMay/June 2025Paper 1 Q351 Mark
The diagram shows a cell of internal resistance 1.0R connected to a variable resistor. [Diagram shows a cell with internal resistance 1.0R connected to an external variable resistor.] When the variable resistor has an initial resistance of 2.0R, the current in the cell is I₁ and the terminal potential difference (p.d.) across the cell is V1. The variable resistor is now adjusted to a new resistance of 4.0R. What is the new current in the cell and the new terminal p.d. across the cell? [Table with columns: current, terminal p.d. and rows A, B, C, D with values.]
ARow A: current: 0.50I1, terminal p.d.: 1.0V1
BRow B: current: 0.50I1, terminal p.d.: 1.2V1
CRow C: current: 0.60I1, terminal p.d.: 1.0V1
DRow D: current: 0.60I1, terminal p.d.: 1.2V1
✓ Correct Answer
The correct answer is D: Row D: current: 0.60I1, terminal p.d.: 1.2V1
📋 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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