Refraction, Reflection, and Absorption

This lecture covers the concepts of refraction, reflection, and absorption of light, including the refractive index, Snell's law, and the behavior of light in different mediums. It also explores the change in refractive index with photon energy, the refractive index in the x-ray regime, and the phase and group velocities. The instructor discusses the complex refractive index, electron density, and mass density, providing examples with elements. Additionally, the lecture delves into the reflectivity, absorption, and transmission properties of materials, making simple assumptions and using compound materials as examples.