WHAT is multiple images?

圖片參考：http://i182.photobucket.com/albums/x4/A_Hepburn_1990/A_Hepburn01May291736.jpg?t=1212053812


Multiple images refer to the images formed are overlapping, making the observer seems to observe more than one images at the same time.
It is not desirable since it will blur one’s observation, and it affects the determination of the distance of the image, the size of the image, e.t.c.
Referring to the figures above, prism reflects the light ray from the object by total internal reflection and forms a clear image.
But in the case of mirror, it makes up of glass and metal. The glass may reflect the light ray from the object and some light ray is refracted to the metal surface and reflected. As the density of glass is higher than that of air, light is deflected towards the normal when it passes through the surface of the glass. Asa result, the path of the light is deflected. And the reflection by the metal surface forms a virtual image. As the two images overlap, multiple images are formed.



2008-05-29 17:38:15 補充：
In case you cannot see the figures clearly, you can right click and download the file to view it.

係多重影像，即係所謂有鬼影，會令個影像無咁清楚。
http://www.badongo.com/pic/3668432