FRQ — Dual Nature of Radiation and Matter

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

Two clean metal plates A and B have work functions

1.8\,\text{eV}

and

2.5\,\text{eV}

respectively. They are separately illuminated with light of wavelengths

500\,\text{nm}

and

400\,\text{nm}

. Use

hc=1240\,\text{eV nm}

Total: 5 marks

(a) For $500\,\text{nm}$ light, state which plate emits photoelectrons. (2 marks)

(b) For $400\,\text{nm}$ light, find the stopping potential for plate B. (2 marks)

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

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