Lesson Plan

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Lesson Plan
Grade: Date: 25/02/2026
Subject: Physics
Lesson Topic: explain that X-rays are produced by electron bombardment of a metal target and calculate the minimum wavelength of X-rays produced from the accelerating p.d.
Learning Objective/s:
  • Describe the process of X‑ray production by electron bombardment of a metal target.
  • Explain the relationship between accelerating potential and minimum X‑ray wavelength.
  • Calculate the minimum wavelength for a given accelerating voltage using λmin = 1240 / V(kV).
  • Distinguish between bremsstrahlung and characteristic X‑ray radiation.
  • Apply the wavelength‑voltage relationship to select appropriate tube voltages for different applications.
Materials Needed:
  • Projector or interactive whiteboard
  • Slide deck with X‑ray tube schematic
  • Worksheet containing example calculations
  • Scientific calculators
  • Whiteboard and markers
  • Optional: physical model or 3‑D printed X‑ray tube
 Introduction:
Begin with a striking image of a modern CT scanner and ask students how invisible radiation can reveal internal structures. Recall that electrons can be accelerated by a voltage and that their collisions produce high‑energy photons. Today’s success criteria are that students will be able to explain X‑ray generation and compute the shortest possible wavelength for a given tube voltage.
Lesson Structure:
  1. Do‑now (5'): Quick quiz on electron acceleration and the relation E = eV; review answers.
  2. Mini‑lecture (10'): Introduce X‑ray tube components, bremsstrahlung vs. characteristic radiation, derive λmin = hc/eV and the convenient formula λmin(nm)=1240/V(kV).
  3. Guided practice (12'): Work through the 30 kV example on the board; students complete worksheet calculations for 10, 20, 50 kV.
  4. Interactive simulation (8'): Use an online X‑ray tube simulator to vary voltage and observe wavelength changes; discuss observations.
  5. Concept check (5'): Exit‑ticket – write the formula and calculate λmin for 50 kV.
  6. Summary discussion (5'): Relate minimum wavelength to applications such as medical imaging and crystallography.
Conclusion:
Recap that the accelerating potential determines the maximum photon energy and thus the minimum wavelength of X‑rays. Students demonstrate understanding through the exit‑ticket calculation. For homework, assign a set of voltages for which learners compute λmin and write a brief paragraph explaining how they would choose a tube voltage for a specific application.