| Lesson Plan |
| Grade: |
Date: 25/02/2026 |
| Subject: Physics |
| Lesson Topic: understand that photoelectrons may be emitted from a metal surface when it is illuminated by electromagnetic radiation |
Learning Objective/s:
- Describe the relationship between photon frequency, energy, and the work function of a metal.
- Explain the key observations of the photoelectric effect and Einstein’s photoelectric equation.
- Calculate the maximum kinetic energy of emitted electrons and the stopping potential for given wavelengths.
- Analyse how light intensity influences the number of emitted electrons without affecting their kinetic energy.
- Apply the concepts to solve typical A‑Level style problems involving threshold frequency and work function.
|
Materials Needed:
- Projector and screen
- PowerPoint slides covering theory and equations
- Printed worksheet with practice problems
- UV lamp or laser pointer for a quick demonstration
- Photoelectric‑effect simulation software (e.g., PhET)
- Calculators
- Handout of the experimental diagram
|
Introduction:
Begin with a quick demonstration using a UV lamp shining on a metal plate to capture students’ curiosity. Recall prior learning about wave‑particle duality and energy quantisation. State that by the end of the lesson they will be able to predict when photoelectrons are emitted and calculate the associated kinetic energies.
|
Lesson Structure:
- Do‑now (5’) – Students answer recall questions on photon energy and momentum on a worksheet.
- Mini‑lecture (10’) – Present key equations (E = hν, p = h/λ) and Einstein’s photoelectric equation with examples.
- Interactive demonstration (8’) – Show a video/live demo of a photoelectric apparatus; discuss observations and threshold frequency.
- Guided practice (12’) – Work through the sodium work‑function example as a class, emphasizing unit conversions.
- Collaborative problem solving (10’) – Pairs solve two revision questions on threshold frequency and stopping potential.
- Concept check (5’) – Quick poll/clicker quiz on intensity vs. frequency effects.
- Summary & reflection (5’) – Teacher revisits objectives; students note one concept they can now explain.
|
Conclusion:
Summarise that photoelectron emission occurs only when photon energy exceeds the metal’s work function and that the stopping potential provides a direct measure of the electrons’ kinetic energy. Ask students to write an exit ticket stating the emission condition and one real‑world application. Assign homework to complete additional problems on calculating threshold frequencies and stopping potentials.
|