An object is located one meter in
front of a plane mirror. Light from the object is reflected
by the plane mirror that produces an image of the object. Which of the following correctly
describes how far behind the mirror the image appears to be? (A) Less than one meter, (B) one
meter, (C) more than one meter.
Let’s begin by drawing a sketch of
this scenario. Say that here is a plane mirror
seen from the side, and then here is an object. And the object is a distance of one
meter from the mirror. Light from the object is reflected
by the mirror. These reflected light rays, when
traced backward, form an image. It’s the image of the object. Because the mirror is a plane
mirror, the distance from the mirror to the image is the same as the distance from
the mirror to the object. In this case, that’s one meter. For a plane mirror, it’s always
true that the distance from the mirror to the object is equal to the distance from
the mirror to the image.