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CAIE
22. Quantum physics
22.1 Energy and momentum of a photon
- understand that electromagnetic radiation has a particulate nature
- understand that a photon is a quantum of electromagnetic energy
- recall and use E = hf
- use the electronvolt (eV) as a unit of energy
- understand that a photon has momentum and that the momentum is given by p = E / c
22.2 Photoelectric effect
- understand that photoelectrons may be emitted from a metal surface when it is illuminated by electromagnetic radiation
- understand and use the terms threshold frequency and threshold wavelength
- explain photoelectric emission in terms of photon energy and work function energy
- recall and use hf = Φ + 1/2mvmax 2
- 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
- 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
- describe and interpret qualitatively the evidence provided by electron diffraction for the wave nature of particles
- understand the de Broglie wavelength as the wavelength associated with a moving particle
- recall and use λ = h / p
22.4 Energy levels in atoms and line spectra
- understand that there are discrete electron energy levels in isolated atoms (e.g. atomic hydrogen)
- understand the appearance and formation of emission and absorption line spectra
- recall and use hf = E1 – E2