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

A metal has threshold frequency

5.0\times10^{14}\,\text{Hz}

. It is illuminated first with light of frequency

8.0\times10^{14}\,\text{Hz}

and intensity

I

, then with the same frequency and intensity

2I

, and finally with frequency

1.0\times10^{15}\,\text{Hz}

at intensity

I

. Take

h=6.63\times10^{-34}\,\text{J s}

and

1\,\text{eV}=1.6\times10^{-19}\,\text{J}

Total: 7 marks

(a) Find the work function in eV. (2 marks)

(b) Find the stopping potential for $8.0\times10^{14}\,\text{Hz}$ light. (2 marks)

(d) Find the stopping potential for $1.0\times10^{15}\,\text{Hz}$ light. (2 marks)

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

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