Unit 05 · Physics 2
Optics
Light as a ray and light as a wave, and the experiments that decide which description you need.
Work through them in order: each lesson assumes the one before it. Every lesson asks you to commit to a prediction, then lets you test it against a simulation of the real equations.
- 01
Reflection & Refraction
Light bends because it changes speed. The rest of what happens at a boundary follows from that, including the angle past which light cannot leave.
Topics: Angles from the normal · Snell's law · Total internal reflection · Dispersion
35 min4 checkpoints - 02
Lenses, Mirrors & Images
Where the picture actually is when there is no screen to catch it, and what covering half the lens does to it.
Topics: Ray diagrams · The thin-lens equation · Real and virtual images · Mirrors
35 min4 checkpoints - 03
Two-Slit Interference
Light plus light makes darkness, and the entire pattern follows from one number: how much further one wave had to travel.
Topics: Path difference · Fringe positions · Missing orders · The small-angle approximation
25 min5 checkpoints - 04
Diffraction & Polarization
The narrower the gap, the wider the spread. And a third polariser lets light through two that had blocked it completely.
Topics: Single-slit diffraction · Gratings · Polarisation · Malus's law
24 min4 checkpoints