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H1 Physics 8867 · Nov 2023PhysicsPaper 1Most challenging

Paper 1 Q20 — Potential at points in a divider

D.C. circuits — potential (not just p.d.) at points in a potential divider

What the examiners said

“This question was found to be challenging. Candidates had difficulty understanding the potential at different points in a potential divider circuit.” The general comments add that circuit questions were challenging overall.

Try the question (reconstruction)

A 12 V battery of negligible internal resistance is connected across a 4.0 kΩ resistor in series with an 8.0 kΩ resistor. The negative terminal is earthed (0 V) and the 4.0 kΩ resistor is connected to the positive terminal. What is the potential at the junction X between the two resistors?
Examiner report: “Candidates had difficulty understanding the potential at different points in a potential divider circuit.”

Explore — walk the potential around the circuit

Adjust the resistors. The right-hand chart plots the potential at every point as you walk from the earthed terminal up through the divider — potential is a ‘height’, and resistors are the downhill slopes.

Set R1 = R2 and the junction sits at exactly 6 V. Make R2 huge and X rises towards 12 V — the junction potential follows the bottom resistor’s share.

Original reconstruction inspired by the misconceptions described in the Singapore-Cambridge GCE A-Level H1 Physics 8867 November 2023 Examiner Report. Not the actual examination question. For classroom exploration.

Made by lookang, using Claude Fable 5. More resources: iwant2study.org