FRQ — Electrostatics

Case study·Standard multi-step (3/5)·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

Two identical conducting spheres A and B carry charges

+6\,\mu\text{C}

and

-2\,\mu\text{C}

respectively. They are touched together and then separated by

0.20\text{ m}

in air. Take

k=9.0\times10^9\text{ N m}^2\text{ C}^{-2}

Total: 5 marks

(a) Find the charge on each sphere after contact. (2 marks)

(b) State whether the force after separation is attractive or repulsive. (1 mark)

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

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