PLANE MIRRORSUnit 3: Light

TERMS:

Plane mirror- a smooth reflecting surface

Virtual image- images formed by a plane mirror. CANNOT be projected onto a screen

Real image- images that can be projected onto a screen (ie. pin hole camera)

CHARACTERISTICS OF PLANE MIRRORS

1. The image is located the same distance behind the mirror (di) as the object is in front of the mirror (do)

di=-do

2. The image (Hi) is the same size as the object (Ho)

Hi=Ho

CHARACTERISTICS CON’T

3. The image is formed upright but laterally inverted (facing the object)

MIRROR EQUATIONS

DRAWING RAY DIAGRAMS

You draw a ray diagram to find where an image is formed in a mirror

Important points: Diagrams need to be neat, labeled and

drawn to scale Solid lines represent the path of a light ray,

arrows show the direction Dotted lines are used to show where the

light ray appears to coming from

DRAWING RAY DIAGRAMS

There are 4 important image characteristics to consider:1. Magnification2. Attitude (upright or inverted)3. Type (real or virtual)4. Position (di)

SEEING HOW THE EYE SEES POINT OBJECTS

1. Draw a perpendicular line from the object to the mirror

2. Extend the line behind the mirror3. Find the image using di=do4. Draw a straight line from the image to the

top of the eye (dotted on the image side)5. Draw another line from the bottom of the

eye6. Where the line strikes the mirror draw a

line back to the object7. Draw arrows to indicate direction

SEE HANDOUT

DRAWING LARGE OBJECTS

Rules:1. Draw perpendicular lines from the top and bottom of

the object to the mirror2. Use do=di to find the image location3. Extend the perpendicular lines past the mirror to the

top or bottom of the image4. Draw a straight line from the top of the image to the

top of the eye (dotted line on image side)5. Draw another line from the bottom of the eye to the

bottom of the image6. Where the ‘image to eye lines’ strike the mirror, draw

lines back to the eye7. Draw arrows on the lines to the eye to indicate

direction