A2 Level QUANTUM PHYSICS | PART 4 | 2025 | Physics By Akhtar Mehmood

Link to our latest notes and resources: https://drive.google.com/drive/u/2/fo... 22 Quantum physics 22.1 Energy and momentum of a photon Candidates should be able to: 1 understand that electromagnetic radiation has a particulate nature 2 understand that a photon is a quantum of electromagnetic energy 3 recall and use E = hf 4 use the electronvolt (eV) as a unit of energy 5 understand that a photon has momentum and that the momentum is given by p = E / c 22.2 Photoelectric effect Candidates should be able to: 1 understand that photoelectrons may be emitted from a metal surface when it is illuminated by electromagnetic radiation 2 understand and use the terms threshold frequency and threshold wavelength 3 explain photoelectric emission in terms of photon energy and work function energy 4 recall and use hf = Φ + 2 1mvmax 2 5 explain why the maximum kinetic energy of photoelectrons is independent of intensity, whereas the photoelectric current is proportional to intensity 22.3 Wave-particle duality Candidates should be able to: 1 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 2 describe and interpret qualitatively the evidence provided by electron diffraction for the wave nature of particles 3 understand the de Broglie wavelength as the wavelength associated with a moving particle 4 recall and use λ = h / p 22.4 Energy levels in atoms and line spectra Candidates should be able to: 1 understand that there are discrete electron energy levels in isolated atoms (e.g. atomic hydrogen) 2 understand the appearance and formation of emission and absorption line spectra 3 recall and use hf = E1 – E2