Module 8: From the Universe to the Atom
11 dot points across 4 inquiry questions. Click any dot point for a focused answer with worked past exam questions where available.
Inquiry Question 3: How is it known that classical physics cannot explain the properties of the atom?
A focused answer to the HSC Physics Module 8 dot point on the Bohr model of hydrogen. Postulates of stationary orbits and quantised angular momentum, the energy levels E_n = -13.6 eV / n^2, the Balmer-Rydberg formula 1/lambda = R (1/n_f^2 - 1/n_i^2), spectral series (Lyman, Balmer, Paschen), and the limitations of the model.
A focused answer to the HSC Physics Module 8 dot point on de Broglie matter waves. The hypothesis lambda = h/p applied to electrons and to macroscopic objects, the Davisson-Germer electron diffraction experiment, and the standing-wave reinterpretation of Bohr's quantised orbits.
A focused answer to the HSC Physics Module 8 dot point on Schrodinger's contribution to the atom. The wavefunction psi, the probability density |psi|^2, the time-independent Schrodinger equation for bound states, atomic orbitals (s, p, d, f) replacing Bohr orbits, and the resolution of multi-electron spectra.
Inquiry Question 2: How is it known that atoms are made up of protons, neutrons and electrons?
A focused answer to the HSC Physics Module 8 dot point on the discovery and properties of the electron. Cathode ray tubes and the particle vs wave debate, Thomson's crossed-field experiment to measure the charge-to-mass ratio e/m, and his plum-pudding model of the atom.
A focused answer to the HSC Physics Module 8 dot point on Millikan's oil drop experiment. Balancing gravity and electrical force on charged oil droplets between parallel plates, the equation mg = qE with E = V/d, the integer-multiple distribution of measured charges, and the value of the elementary charge e.
A focused answer to the HSC Physics Module 8 dot point on the structure of the atom. The Geiger-Marsden gold foil experiment, Rutherford's nuclear model replacing the plum pudding, and Chadwick's 1932 discovery of the neutron using beryllium-alpha collisions and conservation of momentum and energy.
Inquiry Question 4: How is it known that human understanding of matter is still being refined?
A focused answer to the HSC Physics Module 8 dot point on nuclear energy. Mass defect Delta m = Z m_p + N m_n - m_nucleus, binding energy Delta m c^2, the binding-energy-per-nucleon curve with its iron peak, energy release in fission (heavy nuclei split) and fusion (light nuclei combine), and worked examples for both.
A focused answer to the HSC Physics Module 8 dot point on radioactive decay. Alpha, beta-minus, beta-plus and gamma decay with nuclear equations, the decay law N = N_0 e^(-lambda t) and N = N_0 (1/2)^(t / T_1/2), and the relation lambda T_1/2 = ln 2.
A focused answer to the HSC Physics Module 8 dot point on the Standard Model. Three generations of quarks and leptons, the four fundamental forces and their gauge bosons (photon, W and Z, gluons, graviton), the role of particle accelerators in producing and detecting these particles, and the place of the Higgs boson.
Inquiry Question 1: What evidence is there for the origins of the elements?
A focused answer to the HSC Physics Module 8 dot point on the Big Bang and the origin of the elements. Hubble's law v = H_0 d as evidence for expansion, the cosmic microwave background as cooled relic radiation, primordial nucleosynthesis explaining the H/He ratio, and the timeline from the hot dense early universe to the present.
A focused answer to the HSC Physics Module 8 dot point on stars and the elements. The Hertzsprung-Russell diagram, main sequence to red giant to white dwarf or supernova evolution, hydrogen to helium fusion via the p-p chain and CNO cycle, heavier-element fusion up to iron, and the supernova production of elements heavier than iron via the r-process.