A-LevelPhysicsElectricityOct/Nov 2014Paper 1 Q321 Mark
A pencil is used to draw a line of length 30 cm and width 1.2 mm. The resistivity of the material in the pencil is 2.0 × 10⁻⁵ Ω m and the resistance of the line is 40 kΩ. What is the thickness of the line?
A1.25 × 10⁻¹⁰ m
B1.25 × 10⁻⁸ m
C1.25 × 10⁻⁷ m
D1.25 × 10⁻⁵ m
✓ Correct Answer
The correct answer is C: 1.25 × 10⁻⁷ m
📋 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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