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23 Light: Geometric Optics. We see objects by emitted light or reflected light. 23-1 The Ray Model of Light. Light travels in straight lines. A light ray is a model that represents the wave front of a wave as a vector. 23-2 Reflection: Image Formation by a Plane Mirror.
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23 Light: Geometric Optics We see objects by emitted light or reflected light.
23-1 The Ray Model of Light • Light travels in straight lines. • A light ray is a model that represents the wave front of a wave as a vector.
23-2 Reflection: Image Formation by a Plane Mirror • When a light ray strikes a flat surface, the angle between the surface and the ray is called the angle of incidence. • The angle at which the beam leaves the surface is called the angle of reflection. • The angle of incidence and angle of reflection lie in the same plane as the normal to the surface. • The law of reflection states that the angle of incidence equals the angle of reflection.
Diffuse reflection occurs on a surface that is not shiny or has a rough texture… specular reflection occurs on a surface that is smooth or mirrored. • Image distance is usually referred to as d1 or q, where object distance is referred to as p or d0 . • A virtual image is one in which the rays do not actually pass through the image…a real image is one that the rays do pass through.
23-3 Formation of Images by Spherical Mirrors • A concave mirror is one which has the shiny side like the inside of a bowl. • A convex mirror is a mirror that would be like the back side of a bowl having a mirrored surface. • A plane mirror is a flat mirror. • 1/d0 + 1/di = 1/f • Lateral magnification for curved mirror… • M=h1/h0 = di/d0 … where M= magnification.
23-3 Formation of Images by Spherical Mirrors • See Example 23-3 and 694 page 693-4. • See Example 23-6 Convex rearview mirror. • See ray diagram, page 694-695
23-4 Index of Refraction • The speed of light in a vacuum is c=2.99792458 x 108 m/s • Light changes speed, and direction, as it moves through different matter. • N=c/v… where n is the index of refraction for a substance. (See chart pg. 696) • See example 23-7 page 696.
HOMEWORK • PAGE 717 pr# 1,2,5, 9-12, 26-28 due Tuesday BOP