Two copper wires are joined together and carry a current, as shown. [Figure showing two copper wires P (diameter d) and Q (diameter 2d) joined in series carrying a current] Wire P has diameter d and wire Q has diameter 2d. What is the ratio average drift speed of the free electrons in wire P / average drift speed of the free electrons in wire Q?
✓ Correct Answer
The correct answer is D: 4
📋 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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