Year 12 · Units 3 and 4
WACE Physics, Year 12 (Units 3 and 4)
Unit 3 and 4 Physics moves from Year 11's linear mechanics into circular and orbital motion, gravitational and electric fields, and the electromagnetism that underpins how generators and transformers actually work. Unit 4 is where the course changes character most sharply: special relativity and quantum physics ask students to accept that the classical, intuitive physics of Units 1 through 3 breaks down at very high speeds and very small scales. It's conceptually the most demanding stretch of WA's entire senior physics sequence, and it rewards students who are comfortable being told their everyday intuition is, in a precise sense, wrong.
Unit 3
Circular motion, gravitation and electromagnetism.
Circular motion
Analysing uniform circular motion, including centripetal force and acceleration.
Gravity and gravitational fields
Applying Newton's law of universal gravitation and the concept of a gravitational field.
Satellites, orbits and Kepler's laws
Applying gravitation and circular motion to satellites and orbits, using Kepler's laws.
Electric fields and Coulomb's law
Applying Coulomb's law and the concept of an electric field to charged particles.
Magnetic fields and the motor effect
Explaining magnetic fields and the force on a current-carrying conductor (the motor effect).
Electromagnetic induction
Explaining how a changing magnetic field induces an electric current.
Generators and AC current
Explaining how generators produce alternating current using electromagnetic induction.
Transformers and power transmission
Explaining how transformers work and why they matter for efficient power transmission.
Unit 4
Special relativity and quantum physics — where classical intuition genuinely breaks down.
Special relativity
Introducing special relativity through Einstein's postulates and the concept of reference frames.
Time dilation and length contraction
Explaining and calculating time dilation and length contraction at relativistic speeds.
Where students get stuck: Trying to reconcile relativistic effects with everyday intuition instead of accepting the postulates and following the mathematics. This topic is one of the few in the entire WA physics sequence where intuition is actively unhelpful, and that's worth saying explicitly rather than expecting it to eventually "make sense" the ordinary way.
Mass-energy equivalence (E=mc²)
Applying mass-energy equivalence and relativistic momentum.
The photoelectric effect and quantum light
Explaining the evidence for light's quantum nature through black-body radiation and the photoelectric effect.
Wave-particle duality
Explaining wave-particle duality and the concept of matter waves.
Atomic energy levels and spectra
Explaining atomic energy levels and how they produce atomic spectra.
The standard model of particle physics
Introducing the standard model of particle physics.
Particle accelerators
Explaining how particle accelerators are used to investigate the frontier of physics.
How it is assessed
- Unit 3 and Unit 4 combine school assessment, moderated by SCSA, with an external written examination set by SCSA at the end of the year.
- The combined school and examination result is what contributes to the ATAR for this course.
- A course must be completed to at least a C grade average across Units 3 and 4 for the result to count toward the WACE.
Common questions
- Has this syllabus changed recently?
- WACE senior secondary syllabuses are reviewed by SCSA on a rolling basis rather than all at once — there's no single blanket revision date the way there is for the P-10 curriculum. Check senior-secondary.scsa.wa.edu.au for the current syllabus version of this specific course before relying on unit content for assessment planning.
- Why is Unit 4 considered the hardest stretch of the course?
- Because it's the point where the physics genuinely stops matching everyday intuition — relativity and quantum mechanics describe a universe that doesn't behave the way lived experience suggests it should. Units 1 through 3 extend and refine intuitive physics; Unit 4 asks a student to trust the mathematics over their intuition, which is a different and harder kind of demand.
- Does Unit 3's electromagnetism connect back to anything in Unit 1 or 2?
- Yes, closely — generators and transformers in Unit 3 are a direct, practical application of the electric circuit and magnetic principles introduced in Unit 2, now combined with the circular motion concepts from earlier in Unit 3 itself. It's one of the more satisfying connections in the course for a student who's kept up with the sequence.
Related year levels
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Start learning for freeWritten from the current WACE course syllabus. Requirements change — check SCSA for the official syllabus.