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A-LevelPhysicsElectricity9702/12 · Oct/Nov 2018 · Q351 Mark

A wire of length L has resistance R. The cross-section of the wire is circular with radius r. A second wire, also of circular cross-section, and of the same material, has resistance ¾ R. What could be the radius and the length of the second wire?

Aradius: r/2, length: L/2

Bradius: r/√2, length: L/2

Cradius: r√2, length: 2L

Dradius: 2r, length: 2L

✓ Correct answer

D: radius: 2r, length: 2L

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About this question

Topic: Electricity, A-Level Physics (syllabus 9702). Multiple choice, 1 mark.
Source: A-Level Physics, Oct/Nov 2018 Paper 1 Variant 2, question 35.

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