Transcript 11.1 law of reflection and curved mirrors

11.1 Law of Reflection and Plane Mirrors

An image is a reproduction of an object
produced by an optical device like a mirror
When light
reflects off a
surface, the
angle of
incidence is
aways EQUAL to
the angle of
reflection

Incident ray – incoming ray
Reflected ray – ray that bounces off a surface
Normal – a dash line drawn perpendicular to a
mirror at the point of reflection
- its imaginary
Angle of incidence (Ɵi) – angle between the incident ray
and normal
Angle of reflection (Ɵr) – angle between the reflected
ray and normal

The angle of incidence and angle of reflection
are ALWAYS measured from the NORMAL
Why?????

Some surfaces are curved. This makes it
difficult to measure a correct angle from the
surface

When a reflective surface generates an image, the image possesses certain
characteristics:
S = size
An image can be larger or smaller or the same as your object
A = attitude.
An image can be upright or inverted compared to the original object or can
be laterally inverted (left and right switch)
L = location.
The distance between the image and mirror and whether the image is made
in front or behind the mirror
T= type.
The image may be virtual (reflected light rays meet behind the mirror) or real (reflected
light rays meet in front of the mirror and produce an image that can be projected
onto a screen)
A mirror with a flat
reflective surface

Characteristics of an image:
Size= The same height as the object
Attitude = Upright (same direction as object) but laterally inverted
(left and right switch)
Location = same distance behind the mirror as the object is in front
of it
Type = The image is VIRTUAL (reflected rays cross behind the
mirror)

IMAGE IS FORMED
THE SAME
DISTANCE BEHIND
THE MIRROR AS
THE OBJECT IS IN
FRONT OF IT
The light from an object in
front of a mirror has to
travel to the mirror, and
then bounce off it to return
to your eyes

R
L

L
R
Images are reversed
because light rays
that hit a plane
mirror are reflected
right back along the
same path
That means a point
on your left side is
reflected off the right
side of the mirror –
therefore making it
look like the image is
reversed when it
returns to your eyes


P. 420 #1-4
Worksheet drawing reflected rays from a
normal