Physics HL · Chapter 22: Quantum Physics
Chapter 22 Wrap-Up
Consolidate one repeatable quantum workflow from threshold experiments to diffraction geometry.
Estimated time: 10 minutes
One Workflow for Quantum-Evidence Problems
Start by identifying what was measured: stopping voltage, wavelength shift, diffraction angle, or accelerating voltage. Then pick the corresponding model equation set: photoelectric (hf - phi), Compton (delta lambda), or de Broglie/Bragg (h/p and 2d sin theta). Keep evidence type and equation family paired. Most mistakes happen when students mix formulas from different evidence channels.
Chapter 22 Key Takeaways
- Photon model gives quantised interaction energy E = hf and momentum p = h/lambda.
- Photoelectric stopping voltage tracks maximum electron kinetic energy, not beam intensity.
- Compton scattering provides angle-dependent wavelength-shift evidence for photon momentum.
- Matter-wave wavelength decreases with increasing momentum, explaining scale-dependent diffraction visibility.
- Electron diffraction and Bragg geometry directly validate de Broglie's hypothesis.
No new simulation is added in this wrap-up because this section is for synthesis. Re-run the lab modes in sequence (Photon -> Photoelectric -> Compton -> Matter Wave) and predict each output trend before reading values. The goal is model selection fluency, not formula memorization.