Sight is certainly one of our most important senses and depends on the interaction of electromagnetic waves in the visible portion of the spectrum with the eye. The use of materials that reflect light and that refract or bend light extends throughout our industrialized society. In this module we deal with light traveling in two dimensions and encounterinq the boundaries between media under those conditions in which the wavelength is small compared with the size of the obstacles or apertures. Under such conditions, since diffraction and interference effects are negligible, the principal phenomena occurring at the interfaces, reflection and refraction, can be understood and the progress of a wave charted by a simple geometrical procedure: r...