Major purpose of this lecture is to present on Optics and Mirrors. Rays seem to come from behindthe mirror, but, of course, theydon’t. It is virtually as if the rayswere coming from behind the mirror. As far as the eye-brain system isconcerned, the effect is the sameas would occur if the mirror wereabsent and the chess piece were actually located at the spot labeled “virtual image”. A system of mirrors forms an image by gathering rays from an object and then causes them to converge or diverge.