4.4 – CONVEX MIRRORSp. 318 – 320

HOW ARE CONVEX MIRRORS DIFFERENT FROM CONCAVE ONES?

Both mirrors are curved Convex is shaped so the

middle of the mirror is pushing out toward you

Convex mirrors are aka diverging mirrors because reflected rays spread apart (diverge)

after hitting the mirror

CONVEX MIRRORS PRODUCE VIRTUAL IMAGES Rules for drawing images produced

in convex mirrors are the same as those for concave mirrors

images that form are always virtual must extend reflected

rays behind the mirror to make them intersect

DRAWING RAY DIAGRAMS F and C are located on the non-

reflective side of the mirror (because it’s a convex mirror)

When drawing ray diagrams, rays touch the top of the object, and then travel to F or C as though the incident or reflected ray travels through F or C but they don’t actually

RULES TO DRAWING A RAY DIAGRAM1. Rays parallel to the PA reflect as if they had

gone through F

2. Rays appearing to pass through F reflect back parallel to the PA (opposite of #1)

3. [Rays that appear to pass through C reflect back along the same path]

p. 320

STEPS: Draw a ray from the top of the object:

1.Parallel to the PA, which reflects off mirror as if it had gone through F

2.As though it will pass through F, which reflects back parallel to the PA (opposite of #1)

3.[As though it will pass through C, which reflects back along the same path]

p. 320

IMAGE CHARACTERISTICS

L – closer to mirror O – upright S – smaller T – virtual (you have to extend the

reflected rays behind the mirror so they intersect)

DIFFERENCES BETWEEN IMAGES FORMED IN CONCAVE & CONVEX MIRRORS

LOST characteristics in convex mirrors are always the same L – closer to mirror O – upright S – smaller T - virtual

LOST characteristics vary in concave mirrors depending on where the object is placed Between mirror & F Between F & C Beyond C

WHAT ARE CONVEX MIRRORS USEFUL FOR? Convex mirrors produce images that are

smaller, but give a wider field of view than in concave mirrors

Used for: safety (car side mirrors and hallways with

sharp, “blind” corners) security (inspecting underneath cars at the

border, in retail stores)

OBJECTS IN CONVEX MIRRORS ARE CLOSER THAN THEY APPEAR

Objects look farther away then they actually are because the image that forms in the mirror is smaller