A-LevelPhysicsElectricityOct/Nov 2018Paper 1 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?

Q: What is the correct answer to this A-Level Physics question?

The correct answer is D: radius: 2r, length: 2L.

Q: What topic does this question test?

This question tests Electricity in A-Level Physics (syllabus code 9702). It is worth 1 mark.

Aradius: r/2, length: L/2

Bradius: r/√2, length: L/2

Cradius: r√2, length: 2L

Dradius: 2r, length: 2L

✓ Correct Answer

The correct answer is D: radius: 2r, length: 2L

📋 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.

🔒

Unlock the Examiner's Analysis

Join thousands of Cambridge students already using Oracle Prep

About This A-Level Physics Question

Topic

This multiple-choice question tests Electricity in A-Level Physics (syllabus code 9702). It is worth 1 mark.

Source

This question appeared in the Cambridge A-Level Physics Oct/Nov 2018 examination, Paper 1 Variant 2.

Practice on Oracle Prep

Oracle Prep provides AI-powered practice for all Cambridge O-Level and A-Level subjects. Our platform includes topic predictions with 87.7% accuracy, AI essay grading, and a comprehensive question bank spanning 25 years of past papers across 29 subjects.