Image Formation for
Convave Mirrors - Case B
A GIF Animation
To view an object in any type of mirror, a person must sight
along a line at the image of the object. All persons capable of
seeing the image must sight along a line of sight directed towards
the precise image location. As a person sights in a mirror at the
image of an object, there will be a reflected ray of light coming
from the mirror to that person's eye. The origin of this light ray is
the object. A multitude of light rays from the object are incident on
the mirror in a variety of directions; yet as you sight at the image,
one of the many rays will reflect off the mirror and travel to your
eye. To see an object in a mirror, you must sight at the image; and
when you do a reflected ray of light will travel from the mirror to
your eye along your line of sight.
Not all people who are viewing the object in the mirror will
sight along the same geometrical line of sight. The precise direction
of the sight line depends on the location of the object, the location
of the person, and the type of mirror. Yet all of the lines of sight,
regardless of their direction, will pass through the image location.
In fact, the image location is defined as the location where
reflected rays intersect. Since all people see a reflected ray of
light as they sight at an image in the mirror, then the image
location must be the intersection point of these reflected rays.
In the animation above, an object is positioned above the
principal axis of a concave mirror and between the center of
curvature (C) and the focal point (F). The concave mirror will
produce an image of the object which is inverted (positioned below
the principal axis) and located somewhere beyond the center of
curvature (C) of the mirror. Any person viewing this image must sight
at this image position. The animation depicts the path of light to
each person's eye. Different people are sighting in different
directions; yet each person is sighting at the image location. As
seen in the animation, the image location is the intersection point
of all the reflected rays.
For more information on the ray nature of light, visit
The
Physics Classroom. Specific information is available there on the
following topics:
This page was created by
Tom
Henderson of
Glenbrook South
High School.
Comments and suggestions can be sent by e-mail to
Tom
Henderson.
A hearty thanks is due to lab assistant Bryce Mautner for her
assistance with the graphics and GIF animation.
This page last updated on 8/11/98.