The microscopic quantum world offers a range of phenomena, the interpretation and explanation of which require new ideas and concepts not found in the classical world.
Nature of science:
Observations: Much of the work towards a quantum theory of atoms was guided by the need to explain the observed patterns in atomic spectra. The first quantum model of matter is the Bohr model for hydrogen. (1.8)
Paradigm shift: The acceptance of the wave–particle duality paradox for light and particles required scientists in many fields to view research from new perspectives. (2.3)
Understandings:
Photons
The photoelectric effect
Matter waves
Pair production and pair annihilation
Quantization of angular momentum in the Bohr model for hydrogen
The wave function
The uncertainty principle for energy and time and position and momentum
Tunnelling, potential barrier and factors affecting tunnelling probability
Applications and skills:
Discussing the photoelectric effect experiment and explaining which features of the experiment cannot be explained by the classical wave theory of light
Solving photoelectric problems both graphically and algebraically
Discussing experimental evidence for matter waves, including an experiment in which the wave nature of electrons is evident
Stating order of magnitude estimates from the uncertainty principle
Guidance:
The order of magnitude estimates from the uncertainty principle may include (but is not limited to) estimates of the energy of the ground state of an atom, the impossibility of an electron existing within a nucleus, and the lifetime of an electron in an excited energy state
Tunnelling to be treated qualitatively using the idea of continuity of wave functions
Data booklet reference:
Theory of knowledge:
The duality of matter and tunnelling are cases where the laws of classical physics are violated. To what extent have advances in technology enabled paradigm shifts in science?
Utilization:
The electron microscope and the tunnelling electron microscope rely on the findings from studies in quantum physics
Probability is treated in a mathematical sense in Mathematical studies SL sub-topics 3.6–3.7
Aims:
Aim 1: study of quantum phenomena introduces students to an exciting new world that is not experienced at the macroscopic level. The study of tunneling is a novel phenomenon not observed in macroscopic physics
Aim 6: the photoelectric effect can be investigated using LEDs
Aim 9: the Bohr model is very successful with hydrogen but not of any use for other elements