Image Formation for
Plane Mirrors
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 in front of a
plane mirror. The plane mirror will produce an image of the object on
the opposite side of the mirror. The distance from the onject to the
mirror equal the distance from the image to the mirror. Any person
viewing this image must sight at this image position. The animation
depicts the path of several rays of light from the object to the
mirror. This light subsequently reflects such that observers could
sight along a line of sight and view the image. Different people
might sight from different locations; yet each person would sight at
the same 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.
This page last updated on 8/11/98.