Waves and optics: oscillations, sound and light as waves — wave speed, frequency and wavelength, interference, reflection and refraction, and how waves carry energy.
Waves and Optics are oscillations that travel: sound and light, and what happens when a wave meets a boundary, a slit or a lens. The same mathematics describes a guitar string and a radio mast.
| Relationship | Equation | What it tells you |
|---|---|---|
| Wave speed | v = f·λ | Speed from frequency and wavelength |
| Period | T = 1 / f | Time for one full oscillation |
| Refractive index | n = c / v | How much a medium slows light |
| Snell's law | n1·sinθ1 = n2·sinθ2 | Refraction at a boundary |
| Thin lens equation | 1/f = 1/do + 1/di | Object and image distance for a lens |
| Malus's law | I = I0 · cos²θ | Intensity through a polarizer |
