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.
