Topic Cluster

Waves & Optics

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 — the core equations of waves and optics, and every article on the topic — The equations this topic keeps coming back to.

What Are Waves and Optics?

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.

Core equations in waves and optics
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