2. 23 Light: Geometric Optics We see objects by emitted light or reflected light.

3. 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.

4. 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.

5. 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 d 1 or q, where object distance is referred to as p or d 0. 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.

6. 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/d 0 + 1/d i = 1/f Lateral magnification for curved mirror… M=h 1 /h 0 = d i /d 0 … where M= magnification.

7. 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

8. 23-4 Index of Refraction The speed of light in a vacuum is c=2.99792458 x 10 8 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.

9. HOMEWORK PAGE 717 pr# 1,2,5, 9-12, 26-28 due Tuesday BOP