Lesson Plan

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Lesson Plan
Grade: Year 12 Date: 17/01/2026
Subject: Physics
Lesson Topic: recall and use hf = Φ + 21mvmax2
Learning Objective/s:
  • Describe the relationship between photon frequency, energy, and momentum.
  • Apply the photoelectric equation hf = Φ + ½ mvmax² to calculate kinetic energy and electron speed.
  • Calculate photon energy and momentum for given wavelengths using E = hf and p = h/λ.
  • Interpret photon‑energy tables and relate them to real‑world applications such as solar cells.
Materials Needed:
  • Projector and screen
  • Whiteboard and markers
  • Printed worksheet with photon data table
  • Calculator or computer with spreadsheet
  • Laser pointer or LED for demonstration (optional)
  • Student notebooks
 Introduction:
Begin with a quick demonstration of a laser pointer illuminating a metal surface, asking students what they observe. Review the concepts of energy and momentum of light and recall the equation E = hf. State that by the end of the lesson they will be able to use the photoelectric equation to predict electron speeds.
Lesson Structure:
  1. Do‑now (5') – Students convert a given wavelength to frequency and energy.
  2. Mini‑lecture (10') – Derive photon momentum p = h/λ and introduce the photoelectric equation.
  3. Guided example (12') – Work through the 400 nm metal work‑function problem, prompting students to fill steps on the board.
  4. Group activity (15') – Teams calculate energy and momentum for different colours using the provided table and complete a worksheet.
  5. Concept check (5') – Quick clicker quiz on the meaning of Φ and vmax.
  6. Summary discussion (8') – Students explain why light intensity affects electron count but not vmax.
Conclusion:
Recap the key links between frequency, photon energy, momentum and the photoelectric equation. Ask each student to write one exit‑ticket answer: the maximum kinetic energy for a photon of 500 nm. Assign homework to solve three additional photoelectric problems from the textbook.