FLAT MIRRORS Chapter 13: Section 2

Learning Targets  Describe how the angle of incidence is related to the angle of reflection  Explain how surface texture effects reflection  Draw ray diagrams for objects in flat mirrors  Differentiate between a real and a virtual image

Reflection of Light  Light traveling though a single substance, whether it is air, water, or a vacuum, always travels in a straight line.  When the light encounters a different substance however, its path will change

What is Reflection?  If a material is opaque to light, such as dark, polished wood, the light will not pass into it  While part of the light will be absorbed, most of it will be deflected at the surface  The change in the direction of light is called reflection

 All substances absorb at least some incoming light and reflect the rest  A good mirror can reflect about 90 percent of the incident light, but no surface is a perfect reflector

Texture and Reflection  The texture of a surface affects how it reflects light  Light that is reflected from a rough, textured surface, such as paper or cloth, is reflected in many different directions This is called diffuse reflection  Light reflected from a smooth, shiny surface, such as a mirror, is reflected in only one direction This is called specular reflection

Diffuse vs. Specular Reflection

Angle of Reflection  The angle at which a ray of light strikes a surface is known as the angle of incidence  The angle at which the ray of light is reflected from the surfaces is known as the angle of reflection  When an incoming ray of light strikes a smooth reflecting surface at a specific angle it will be reflected at the same angle  Angle of incidence = Angle of reflection

The line perpendicular to the reflecting surface is referred to as the normal to the surface

Flat Mirrors  The simplest type of mirror is a flat mirror  If an object is placed in front of a flat mirror and light bounces off of it, light rays will spread from the object and reflect from the mirror  To an observer looking at the mirror, these rays appear to come from a location on the other side of the mirror

Virtual Images  An object’s image is said to be at this location behind the mirror because the light appears to come from that point  The image formed by rays that appear to come from behind the mirror, but never really do, is called a virtual image

Ray Diagrams  Image location can be predicted with ray diagrams  Ray diagrams, are drawings that use simple geometry to locate an image formed by a mirror m/phy_demo/flat_mirr or/mirror.html