A-LevelPhysicsD.C. circuits9702/12 · May/June 2020 · Q351 Mark
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]
This question uses a diagram from the original paper, which isn't shown here. Open the full paper from the past papers archive to see it.
AGraph 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.
BGraph showing potential V decreasing piecewise linearly, with the least steep gradient in the first section and progressively steeper gradients in subsequent sections, reaching 0 at Y.
CGraph showing potential V decreasing in discrete steps.
DGraph showing potential V decreasing piecewise linearly, with the same gradient in all sections.
✓ Correct answer
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.
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