A-LevelPhysicsD.C. circuits9702/12 · Oct/Nov 2012 · Q381 Mark

A light-dependent resistor R has resistance of about 1 MΩ in the dark and about 1 kΩ when illuminated. It is connected in series with a 5 kΩ resistor to a 1.5 V cell of negligible internal resistance. [Figure showing circuit with LDR and fixed resistor] The light-dependent resistor is illuminated (in an otherwise dark room) by a flashing light. Which graph best shows the variation with time t of potential difference V across R?

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.

A[Graph option A]

B[Graph option B]

C[Graph option C]

D[Graph option D]

✓ Correct answer

B: [Graph option B]

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Topic: D.C. circuits, A-Level Physics (syllabus 9702). Multiple choice, 1 mark.
Source: A-Level Physics, Oct/Nov 2012 Paper 1 Variant 2, question 38.

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