This is a simulation to illustrate the processes involved in the formation of images in plane mirrors. When the control points are visible, you can move the object (the blue arrow), the four points where the (blue) incident rays strike the mirror, as well as the two ends of the mirror itself. The diagram shows two real rays coming from both the top and bottom of the object. The green rays show where the diverging real reflected rays go, and the red dotted rays show the virtual rays which converge to form the virtual image behind the mirror.

[list=1][*] Move point X to see how different rays of light bouncing off the same point on the object in different directions reflect off the mirror. If your eye catches several of these rays, what common point will they all have appeared to come from?[br][/*][*]Repeat with points Y.[/*][/list]