A conductor consists of three wires connected in series. The wires are all made of the same metal but have different cross-sectional areas. There is a current I in the conductor. [Figure 35.1] Point Y on the conductor is at zero potential. Which graph best shows the variation of potential V with distance along the conductor? [Figure 35.2]
✓ Correct Answer
The correct answer is A: Graph showing potential V decreasing piecewise linearly, with the steepest gradient in the first section and progressively less steep gradients in subsequent sections, reaching 0 at Y.
📋 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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