Homework
9.18 - charge flow in glass
9.19 - skin depth in a poor conductor
9.21 - air-to-silver interface
9.22 - nonlinear dispersion examples - water and Schroedinger particle
9.23 - numbers for simple atomic oscillator model
9.25 - group velocity in anomalous dispersion

Examples class
9.20 - energy density for wave in conductor
9.24 - width of anomalous dispersion region

Bonus
B1 - Rainbows. Assuming ray optics, explain the origin of first-order rainbows as a result of refraction and internal reflection by spherical water droplets. Show, analytically or using a computer, that the scattering angle has a maximum (a caustic) as a function of the perpendicular distance of the incident ray from the center of the droplet, at a value that is independent of droplet size. Show that this peak angle is higher for lower refractive index, ie, for red light, so that the outside of the rainbow is red. Plot the distribution of scattering angles for a particular refractive index.