Optics.gsp
Form 3 Optics
Image formed by a convex lens
This is a prototype of JavaSketchpad,
a World-Wide-Web component of The Geometer's Sketchpad. Copyright & copy ; 1990-1998 by Key Curriculum Press, Inc. All rights reserved. Portions of this work
were funded by the National Science Foundation (awards DMI 9561674 & 9623018).
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The above diagram explains how the image is formed by a convex lens.
The main purpose of this page is to let you appreciate how useful geometry is.
Using only some simple geometric constructions, we can explain a law that seems
to have no relation with geometry!
The above diagram explains how the arrow image is formed by a convex lens
in real situation. You can see clearly that the arrow image formed is not symmetric. However, it
is not true when the object is very near to F.
Please note that in most textbook, the object is assumed to be placed at exactly at the same
object distance for the whole arrow. It can only be done in a 3-dimenional sense. The above
diagram shows the object with part of it closer to the lens, and part of it away from the lens!
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