Reflection and Refraction

Abstract

where n1 and n2 are the indices of refraction of the two materials, θ1 is the incident angle, and θ2 is the refracted angle. The index of refraction is defined as the ratio of the speed of light in vacuum (space) over the speed of light in the material in question. Mathematically, n ≡ c/v. For air, n ≃ 1, and for water n = 1.33, whereas often n = 1.5 for glass. It has also been found that n will vary as a function of wavelength (or color) of light. Thus, white light entering a second material will have its different colors refracted at different angles and often the separate colors will become observable. A geometrical derivation for Snell’s Law can be found in most Physics texts. In general when light hits the interface between two different media, some of the light will be reflected and some will be refracted, with each obeying the above laws, accordingly. This is shown in figure 2. The amount reflected versus refracted depends on several variables, including the indices of refraction and the incident angle.