C35 - Principles of Ray Optics

ray approximation

modeling light waves as individual, uniform lines

photon energy

E = hf

Planck’s constant

6.63×10^-34 J • s

Law of reflection

Law of refraction

refractive index

*As λ ↓, n ↑ (since v ∝ λ)

*λ_n = wavelength in medium with refractive index n

Snell’s Law

Huygens’s principle

All points on a wave front produce secondary waves (wavelets), which in tandem create an approximate wave front over time

dispersion

refractive index is a function of wavelength

• big λ → small n (less bending)

• small λ → big n (more bending)

total internal reflection

when n_{in medium} > n_{outside medium} (n₁ > n₂) & θ ≥ θ_c, the light gets reflected back into the medium

• θ_c = critical angle

• sin(θ_c) = n₂/n₁

  • n_{1 =} n_{in medium}

  • n₂ = n_{outside medium}

refractive indices

n_air = 1

n_water = 1.333

n_{glass (crown/flint)} = 1.52/1.66

n_diamond = 2.419