Textbook Reference 10.4 (P.431-434)
Convex Mirrors
 A mirror with a surface curved outward is a convex
mirror, also called a diverging mirror
 A convex mirror spreads out the rays.
Uses for Convex Mirrors
 Because convex mirrors allow you to see more than
plane mirrors, they are often used for security in
stores as well as rear-view mirrors in cars.
Images Formed by Convex Mirrors
 All images in a convex mirror are virtual.
 The reflected light rays never meet and the image
appears to come from behind the mirror.
Images in Convex Mirrors
 Rules are similar to those for concave mirror except:
 Focus is now called VIRTUAL FOCUS
 Both F and C are behind the mirror
 Light rays reflecting off a convex mirror diverge (this is why
a convex mirror is called a diverging mirror)
 Light rays seem to come from an apparent light source
behind the mirror
 Creates virtual images
handout
Light Rays in a Convex Mirrors
 RULE: If the incident ray is parallel to the principal
axis, it will reflect as though coming from F.
handout
Light Rays in a Convex Mirrors
 RULE: If the incident ray is directed at the focus, it
will reflect as parallel to the principal axis.
handout
Light Rays in a Convex Mirrors
 RULE: If the incident ray is directed at the centre of
curvature, it will reflect straight back on itself.
handout
Steps to Locating Images in Convex
Mirrors ... STEP 1
 Draw ray 1 from the top of the object.
 The incident ray parallel to the principal axis reflects
out, as if it came from the focus.
 Extend the reflected ray behind the mirror.
handout
Steps to Locating Images in Convex
Mirrors ... STEP 2
 Draw ray 2 from the top of the object.
 The incident ray is aimed at the focus, and reflects
parallel to the principal axis.
 Extend the reflected ray behind the mirror.
handout
Steps to Locating Images in Convex
Mirrors ... STEP 3
 Draw the image where the two rays converge to the
parallel axis.
handout
Steps to Locating Images in Convex
Mirrors ... CHECK
 Draw the third ray to check the image.
 Incident and reflected rays go through the centre of
curvature. If it intersects, your drawing is correct.
Point of
intersection for
all 3 rays
C
handout
Properties of Images in Convex Mirrors
 Image will always be:
 Size = SMALLER
 Attitude = UPRIGHT
 Location = BEHIND THE MIRROR
 Type = VIRTUAL
 Convex mirrors are useful as security mirrors in stores
and side-view mirrors on vehicles.
Some Uses for Convex & Concave Mirrors
 CONVEX mirrors are useful as security mirrors in
stores & side-view mirrors on vehicles.
 CONCAVE mirrors are useful as flashlights, telescopes,
car headlights, dental examination lights, and other
applications.
HOMEWORK
 TEXTBOOK
 P.434 Learning Check #1,3,4
 WORKSHEET
 “Curved Mirror”