1. Reflection and Light
Flat Mirrors

2. Reflection of Light
Reflection – the turning back of an electromagnetic wave at the surface of a substance
A good mirror can reflect about 90 percent of the incoming light
Diffuse reflection – light reflected from a rough textured surface
Reflected waves are scattered
Specular reflection – light reflected from a smooth shiny surface such as a mirror or still water
Light is reflected in only one direction

3. Reflection of Light

4. Reflection of Light Incoming and reflected angles are equal
Law of reflection – the angle of incoming light ray is equal to the angle of reflected light ray in specular reflection
Angle of incidence – the angle between a ray that strikes a surface and the normal to that surface at the point of contact
Symbolized by θ
Angle of reflection – the angle formed by the line normal to a surface and the direction in which a reflected ray moves
Symbolized by θ’

5. Reflection of Light

6. Flat Mirrors Flat mirrors produce images behind the mirror
Virtual image – an image formed by light rays that only appear to intersect
Can never be displayed on a physical surface
Object distance – the distance from the object to the mirror
Image distance – the distance the image appears to be behind the mirror’s surface
Object distance and image distance are equal
Object size and image size are equal

7. Flat Mirrors
Ray diagrams – drawings the use simple geometry to locate an image formed by a mirror
Draw the object and the mirror
Draw the image the same height and distance as the object
Object distance is called p
Image distance is called q

8. Flat Mirrors
Draw two rays originating from the same location on the object
The first ray is perpendicular to the mirror’s surface
Since the reflected ray will be along the same path, make it a double headed ray
The second ray is not perpendicular
Draw the reflected ray; remember the angle of incidence equals the angle of reflection
Extend both reflected rays into the mirror (use dotted lines to represent rays into and behind the mirror)
Where they cross is the location of the image

9. Flat Mirrors