FRQ — Current Electricity

Case study·Hard exam skill (4/5)·Calculator allowed

Difficulty guide

The label describes the problem, not your ability.

1/5 - Foundational

Warm-up setup; checks one basic idea.

2/5 - Routine exam skill

Normal syllabus skill; usually one main rule or interpretation.

3/5 - Standard multi-step

Exam-style problem with multiple steps or a common trap.

4/5 - Hard exam skill

High-end exam problem; combines methods carefully.

5/5 - Challenge

Stretch problem beyond normal exam pressure.

Question

A long copper wire of area

1.0\times10^{-6}\text{ m}^2

carries a steady current of

1.6\text{ A}

. The electron density is

8.0\times10^{28}\text{ m}^{-3}

. A classroom discussion compares charge transfer through a section with the slow drift of individual electrons.

Total: 5 marks

(a) Find the charge crossing any section in 30 s. (1 mark)

(b) Find the electron drift speed. (2 marks)

Your response (optional — you can also work on paper)

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