# Exercise 5.2.5 Rayleigh Scattering

 1. Generate some numbers for scattering cross sections using the equations given. Look, e.g., at "air" molecules including some water vapor or ozone as scatterers, and wave lengths from the IR to the UV. 2. Derive or justify the equation lsc = 1/ns. Show that for air we get lsc (=) 160 · l4 if we give l in km and l in µm. Hint 1: Consider the particle to be a cube with s being the area of a face. All light will be scattered if the total area of those cubes projected on a surface perpendicular to the light beam covers that area completely. lsc then is the length of a cube that contains enough particle to meet that condition. Hint 2: The volume of an air "molecule" can be estimated from the fact the liquid air has about the same density as water. 3. Generate some numbers for penetration depths in air. How thick does an ozone (O3) layer with a density nOz = 8 ml/m3 have to be to absorb most of the incoming ultraviolet radiation (especially "UV-B"; l » 300 nm) Link to the solution

5.2.5 Not so Perfect Materials

Complex Index of Refraction of Silicon

Polarizing IR and UV Light

Solution to 5.2-3: Attenuation of Light

Solution to Exercise 5.2-3: Rayleight Scattering