Year 12 – Nature of light

New material to the syllabus highlighted in blue
Material modified from the old syllabus in yellow
Material moved from options to core syllabus

Electromagnetic Spectrum

Inquiry question: What is light?


  • investigate Maxwell’s contribution to the classical theory of electromagnetism, including:
    • unification of electricity and magnetism
    • prediction of electromagnetic waves
    • prediction of velocity (ACSPH113)
  • describe the production of electromagnetic waves and relate these processes qualitatively to the predictions made by Maxwell’s electromagnetic theory (ACSPH112, ACSPH113)
  • conduct investigation of historical and contemporary methods used to determine the speed of light and its current relationship to the measurement of time and distance (ACSPH082)
  • conduct an investigation to examine a variety of spectra produced by discharge tubes, reflected sunlight or incandescent filaments
  • investigate how spectrometry can be used to provide information about:
    • the identification of elements
  • investigate how the spectra of stars can provide information on:
    • surface temperature
    • rotational and translational velocity
    • density
    • chemical composition

Resource – Maxwell and Electromagnetism – 2 pages

Investigation – Spectroscopy- 3 pages

Resource-Stellar Spectra-5 pages

Light: Wave Model

Inquiry question: What evidence supports the classical wave model of light and what predictions can be made using this model?


  • conduct investigations to analyse qualitatively the diffraction of light (ACSPH048, ACSPH076)
  • conduct investigations to analyse quantitatively the interference of light using double slit apparatus and diffraction gratings (d\sin{\theta} = m\lambda) (ACSPH116, ACSPH117, ACSPH140)
  • analyse the experimental evidence that supported the models of light that were proposed by Newton and Huygens (ACSPH050, ACSPH118, ACSPH123)
  • conduct investigations quantitatively using the relationship of Malus’s Law (I = I_{max}\cos{^2\theta}) for plane polarisation of light, to evaluate the significance of polarisation in developing a model for light (ACSPH050, ACSPH076, ACSPH 120)

Resource – Newton vs Huygens – 2 pages

Light: Quantum Model

Inquiry question: What evidence supports the particle model of light and what are the implications of this evidence for the development of the quantum model of light?


  • analyse the experimental evidence gathered about black body radiation, including Wein’s Law \big( \lambda_{max} = \frac{b}{T} \big),  related to Plank’s contribution to a changed model of light (ACSPH137)
  • investigate the evidence from photoelectric effect investigations that demonstrated inconsistency with the wave model for light (ACSPH087, ACSPH123, ACSPH137)
  • analyse the photoelectric effect (E_k = hf - \phi) as it occurs in metallic elements by applying the law of conservation of energy and the photon model of light, (ACSPH119)

Light and special relativity

Inquiry question: How does the behaviour of light affect concepts of time, space and matter?


  • analyse and evaluate the evidence confirming or denying Einstein’s two postulates:
    • the speed of light in a vacuum is an absolute constant
    • all inertial frames of reference are equivalent (ACSPH131)
  • investigate the evidence, from Einstein’s thought experiments and subsequent experimental validation, for time dilation \Bigg( t = \frac{t_{o}}{\sqrt{\big(1-\frac{v^2}{c^2}}\big)} \Bigg)
  • and length contraction \bigg( l = l_{o}{\sqrt{\big(1-\frac{v^2}{c^2}}\big)} \bigg), and analyse quantitatively situations in which these are observed, for example:
    • observations of cosmic-origin muons at the Earth’s surface
    • atomic clocks (Hafele-Keating experiment)
    • evidence from particle accelerators
    • evidence from cosmological studies
  • describe the consequences and applications of relativistic momentum with reference to:
    • p_{v} = \frac{mv}{\sqrt{\big( 1-\frac{v^2}{c^2}\big)}}
    • the limitation on the maximum velocity of a particle imposed by special relativity (ACSPH133)
  • Use Einstein’s mass-energy equivalence relationship EQN to calculate the energy released by processes in which mass is converted to energy, for example: (ACSPH134)
    • production of energy by the sun
    • particle-antiparticle interactions, e.g. positron-electron annihilation
    • combustion of conventional fuel

Resource – Special Relativity – 3 pages

Resource – E=mc2 – 1 page

PDF – All ‘Nature of Light’ documents
PDF – All Year 12 Modules