Mirrors

Characteristics & Ray Diagrams

Plane Mirrors

Plane Mirror = a flat, smooth surface that reflects light by regular reflection.

• Created by coating glass with Silver• Rays are reflected with equal angles of

incidence and reflection

Plane Mirrors Vocabulary

• Object = the source of spreading of light rays • Virtual Image = object seen in mirror

– Same size– Same direction (up and down)– Reversed (left to right)– Appears to be behind mirror as far back as it is in

front of mirror

Ray Diagram Properties

• Mirror Line (MN) = where mirror is located• Line of Sight = line from image to an extreme

angle (> 300)• Reflected Ray = line traveling down line of

sight from beyond mirror (arrow pointing away from mirror)

• Incident Ray = line traveling from object to where reflected ray hits mirror line (arrow pointing toward mirror)

Ray Diagram Properties (cont.)• Normal line = line perpendicular to mirror,

starting at point where incident & reflected ray converge

• Angle of Incidence = made from incident ray and normal line

• Angle of Reflection = made from reflected ray and normal line

• Angle of Incidence & Angle of Reflection should be equal.

M N

P1

P

Reflected RayReflected Ray

Incident Ray

Normal Line

Reflected Angle

Incident Angle

Curved Mirrors

• Reflection comes from inner “caved in” surface

• Rays will reflect with equal angles of incidence and reflection

• Rays parallel to the principal axis reflect and cross the principal axis at a point called the “focal point”

Curved Mirrors (cont.)

• Focal point (F) is located ½ the distance between the Center of curvature (C) and the mirror

• Concave mirrors produce a “real image” because the rays converge at a location in front of the mirror

P P1

M

N

C F

f

V

R

Parts of a Concave Mirror

Converge light to (F)

Parts of a Convex MirrorM

N

CF

Diverge light from (F)

P P1

M

N

C F

Rays Used to Find an Image

#1

#1

#2

#2

#3image

Image = smaller, upside down, real