The Nature and Propagation of Light
Blue lakes, ochre deserts, green forests, and multicolored rainbows can be enjoyed by anyone who has eyes with which to see them. But by dying the branch of physics called optics, which deals with the behavior of light and other electromagnetic waves, we can reach a deeper appreciation of the visible world. A knowledge of the properties of light allows us to understand the blue color of the sky and the design of optical devices such as telescopes, microscopes, cameras, eyeglasses, and the human eye. The same basic principles of optics also lie at the heart of
modem developments such as the laser, optical fibers, holograms, optical computers, and new techniques in medical imaging.
The importance of optics to physics, and to science and engineering in general, is so great that we will devote the next five chapters to its study. In this chapter we begin with a study of the laws of reflection and refraction and the concepts of dispersion, polarization, and scattering of light. Along the way we compare the various possible descriptions of light in terms of particles, rays, or waves, and we introduce Huygens’ principle, an important link that connects the ray and wave viewpoints. In Chapters 35 and 36 we’ll use the ray description of light to understand how mirrors and lenses work, and we’ll see how mirrors and lenses are used in optical instruments such as cameras, microscopes, and telescopes. We’ll explore the wave characteristics of light further in Chapters
37 and 38.