Lesson Plan

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Lesson Plan
Grade: Date: 17/01/2026
Subject: Physics
Lesson Topic: use the electronvolt (eV) as a unit of energy
Learning Objective/s:
  • Describe the relationship between photon energy, frequency, and wavelength.
  • Convert photon energies between joules and electronvolts using the conversion factor.
  • Apply the formula E(eV)=1240/λ(nm) to determine photon energy from wavelength.
  • Calculate photon momentum in SI units and in eV·c⁻¹.
  • Solve problems involving photon energy and momentum using the provided equations.
Materials Needed:
  • Projector or interactive whiteboard
  • Slides with equations and diagrams
  • Handout with conversion tables and practice questions
  • Scientific calculators
  • Whiteboard and markers
  • Sample spectra images (optional)
 Introduction:
Begin with a quick demonstration of a laser pointer and ask students how we can quantify the light’s energy. Recall that photon energy is linked to frequency and wavelength, concepts they have explored in previous lessons. Explain that today they will learn to express this energy in electronvolts, a convenient unit for atomic‑scale phenomena, and will know how to use it in calculations.
Lesson Structure:
  1. Do‑now (5'): Students answer a short question on converting J to eV on a worksheet.
  2. Mini‑lecture (10'): Review photon relations and introduce the eV conversion factor and the 1240/λ formula, with projected examples.
  3. Guided practice (12'): Work through the green‑light example together, showing each calculation step.
  4. Collaborative problem solving (15'): In pairs, students tackle the four practice questions, using calculators; teacher circulates to check understanding.
  5. Concept check (5'): Quick quiz via clickers or show of hands on key formulas.
  6. Summary discussion (3'): Highlight common pitfalls and real‑world applications (spectroscopy, X‑rays).
Conclusion:
Summarize how electronvolts simplify photon‑energy calculations and reinforce the link between energy, wavelength, and momentum. For exit, each student writes one formula they found most useful on a sticky note. Assign homework: complete a worksheet converting wavelengths of visible, UV, and X‑ray photons to eV and calculate the corresponding momenta.