Optics
Geometric and wave optics — reflection, refraction, thin lenses, mirrors, interference and diffraction.
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Reflection & Refraction
- Law of reflection: i = r.
- Snell's law: n₁ sinθ₁ = n₂ sinθ₂.
- Total internal reflection when light goes from higher to lower n and i > critical angle.
i = r
n₁ sinθ₁ = n₂ sinθ₂
sin θ_c = n₂/n₁
Lenses & Mirrors
- Thin lens equation: 1/v − 1/u = 1/f (sign convention dependent).
- Magnification m = h′/h = v/u.
- Converging lens/mirror: f > 0 (usual Cartesian convention for lenses).
1/v − 1/u = 1/f
m = v/u
Wave Optics
- Young's double slit: fringe width β = λD/d.
- Single-slit diffraction minima: a sinθ = mλ.
- Polarization: light is transverse; polarizers obey Malus's law.
β = λD/d
a sinθ = mλ
I = I₀ cos²θ
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