A-LevelPhysicsElectricityOct/Nov 2020Paper 1 Q331 Mark

Four point charges, each of charge Q, are placed on the edge of an insulating disc of radius r. The disc rotates at a rate of n revolutions per unit time. [Figure 33.1] What is the equivalent electric current at the edge of the disc?

Q: What topic does this question test?

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

A4Qn

B4Q / n

C8πrQn

D2Qn / (πr)

✓ Correct Answer

The correct answer is A: 4Qn

📋 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.

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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 2020 examination, Paper 1 Variant 2.

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