Chapter25TheReflectionofLightMirrors-Physics.PDFVIP

Chapter 25 The Reflection of Light: Mirrors 25.1 Wave Fronts and Rays Defining wave fronts and rays. Consider a sound wave since it is easier to visualize. Shown is a hemispherical view of a sound wave emitted by a pulsating sphere. The rays are perpendicular to the wave fronts (e.g. crests) which are separated from each other by the wavelength of the wave, λ . 25.1 Wave Fronts and Rays The positions of two spherical wave fronts are shown in (a) with their diverging rays. At large distances from the source, the wave fronts become less and less curved and approach the limiting case of a plane wave shown in (b). A plane wave has flat wave fronts and rays parallel to each other. We will consider light waves as plane waves and will represent them by their rays. 25.2 The Reflection of Light LAW OF REFLECTION FROM FLAT MIRRORS. The incident ray, the reflected ray, and the normal to the surface all lie in the same plane, and the angle of incidence, θ , equals the angle of reflection, θ . i r θ = θ i r 25.2 The Reflection of Light In specular reflection, the reflected rays are parallel to each