Reflection and Light Flat Mirrors

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

Reflection of Light

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’

Reflection of Light

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

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

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

Flat Mirrors