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Unit 4: Revolutions in Modern Physics

4 dot points, in syllabus order. Each dot point has a focused answer, with exam-style questions and worked answers where available.

How do atoms emit light and how do nuclei release energy?

Explain atomic energy levels and spectra and analyse nuclear decay and mass-energy in reactions.

Bohr energy levels and line spectra, radioactive decay and half-life, and how mass defect and binding energy explain the energy released in nuclear reactions.

9 min read →

What are the fundamental building blocks of matter?

Describe the Standard Model's particles, the four fundamental forces and their carriers.

The Standard Model of particle physics: quarks and leptons, the four fundamental forces, force-carrying bosons, and how protons and neutrons are built from quarks.

9 min read →

Why does light behave like a stream of particles?

Use the photon model and Einstein's photoelectric equation to explain the photoelectric effect.

How the photoelectric effect reveals light as photons of energy E equals h f, Einstein's photoelectric equation, work function and threshold frequency.

9 min read →

What happens to space and time at very high speeds?

Apply Einstein's postulates to time dilation, length contraction and mass-energy equivalence.

Einstein's two postulates and their consequences: time dilation, length contraction and the equivalence of mass and energy expressed by E equals m c squared.

9 min read →