A-LevelPhysicsElectricityMay/June 2024Paper 1 Q321 Mark
A cylindrical wire has cross-sectional area A and number density of free electrons n. The wire has current I and the free electrons have average drift speed v. A second cylindrical wire has cross-sectional area 0.5A and number density of free electrons 2n. In this wire, the free electrons have average drift speed 2v. What is the current in the second wire?
A0.5I
BI
C2I
D4I
✓ Correct Answer
The correct answer is C: 2I
📋 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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