| Lesson Plan |
| Grade: |
Date: 25/02/2026 |
| Subject: Physics |
| Lesson Topic: understand that the photoelectric effect provides evidence for a particulate nature of electromagnetic radiation while phenomena such as interference and diffraction provide evidence for a wave nature |
Learning Objective/s:
- Describe how the photoelectric effect demonstrates the particle nature of light.
- Explain how interference and diffraction experiments provide evidence for the wave nature of light.
- Apply key equations (E = hν, Kₘₐₓ = hν − φ, d sinθ = mλ, a sinθ = mλ) to solve quantitative problems.
- Compare wave and particle descriptions using the principle of complementarity.
- Evaluate experimental data to determine whether it supports a wave or particle interpretation.
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Materials Needed:
- Projector and screen for slides
- UV lamp, metal plate, voltmeter, and power supply for photoelectric demo
- Laser pointer and double‑slit slide
- Single‑slit apparatus or diffraction grating
- Rulers/calipers for measuring fringe spacing
- Worksheets with data tables and problem sets
- Whiteboard and markers
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Introduction:
Begin with a quick demonstration: shine a UV lamp onto a metal plate and ask students what they expect to happen. Recall prior learning about the energy of light and wave phenomena such as interference. Explain that today they will investigate two classic experiments that reveal opposite aspects of light and will be able to state the supporting evidence by the end of the lesson.
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Lesson Structure:
- Do‑now (5') – Short quiz on wave vs. particle concepts from the previous lesson.
- Mini‑lecture (10') – Review the photoelectric effect, Einstein’s equation, and key observations.
- Demonstration (10') – UV lamp experiment; students record stopping potential vs. frequency and discuss particle evidence.
- Interactive simulation (8') – Online double‑slit simulation; measure fringe spacing and calculate wavelength (wave evidence).
- Hands‑on activity (12') – Laser pointer with double‑slit and single‑slit diffraction; collect data and compare with theory.
- Guided discussion (8') – Synthesize results and introduce Bohr’s complementarity principle.
- Check for understanding (5') – Exit ticket: one sentence stating which experiment supports which nature.
- Summary & homework (2') – Recap key equations and assign a worksheet with quantitative problems.
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Conclusion:
Summarise how the photoelectric effect confirms light’s particle character while interference and diffraction confirm its wave character, emphasizing the complementarity principle. Ask students to write a concise statement on their exit ticket that captures this duality. For homework, complete the worksheet containing quantitative problems on both phenomena.
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