Plane Mirrors

Perhaps our most familiar optical experience is looking into a mirror. Figure shows a point of source of light O, which we call the object, placed a distance o in front of a plane mirror. The light that falls on the mirror is represented by ray emanating from O. *at the point at which each ray strikes the mirror we construct a reflected ray, using the law of reflection. If we extend the reflected ray backward, they intersect at a point I, which we call the image of the object O. the image is the same distance behind the mirror that the object o is in front of it, which we prove below.

Images of diverging light in plane mirrors are always virtual. We know from daily experience how “real” such a virtual image appears to be and how definite is its location in the space behind the mirror, even though this space may, in fact, be occupied by a brick wall.