Unit 5 · 7 lessons
Revolutions in Modern Physics
Where classical physics breaks: time and length that depend on motion, light that arrives in packets, matter that diffracts like a wave, and the small set of particles everything is made of.
- 74 practice questions
- 59 flashcards
- 2 interactive lessons
Lessons
- 1Special RelativityEinstein's two postulates, and the surprising results that follow from taking them seriously: simultaneity that depends on the observer, moving clocks that run slow, moving objects that shorten, and mass that is a form of energy.11 questions
- 2Mass-Energy Equivalence and Relativistic EnergyWhat E = mc² really says: every mass carries a rest energy, a moving object's total energy is γmc², and the same bookkeeping explains why nothing with mass reaches the speed of light, where the energy of fission and fusion comes from, and how light can turn into matter.10 questions
- 3Blackbody Radiation and Planck's Quantum HypothesisWhy hot objects glow red, then white, then blue-white, how Wien's law reads temperature from colour, why classical physics predicted an 'ultraviolet catastrophe', and how Planck's idea that energy comes in steps of hf started quantum physics.11 questions
- 4Photons and the Photoelectric EffectWhy light shining on a metal can knock electrons out, why only the colour of the light decides how fast they leave, and how that forced physicists to accept that light arrives in packets of energy called photons.Interactive11 questions
- 5Matter Waves and Wave-Particle DualityPhotons carry momentum, electrons diffract like waves, and atoms emit light only at particular wavelengths. Together these show that light and matter both have a wave side and a particle side.11 questions
- 6The Uncertainty Principle and Probability WavesWhat happens when photons or electrons pass through a double slit one at a time, why the wave describes probability rather than a smeared-out particle, how Heisenberg's uncertainty principle limits what can be known, and how tunnelling powers microscopes that can see single atoms.Interactive10 questions
- 7The Standard Model of Particle PhysicsThe small set of particles everything is built from — quarks, leptons and force-carrying bosons — how quarks combine into hadrons, what antimatter is, and how particle accelerators turn energy into new matter.10 questions