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Re: Virtual and Real Images



One of the most complete optical simulations is available at
http://webphysics.davidson.edu/Applets/optics4/default.html

This is a complete simulated optical bench. One of the problems is that it
does not have any clues as to the direction of propagation of the light
rays. If the students do not have a good mental picture of what is going
on, they may not understand the simulation. A good feature is that it can
show more rays other than the usual rays through just the focal points and
the center. This is necessary for dispelling some misconceptions.

You can put an aperture so that the students can see the effect of the
aperture. Unfortunately you can not obscure either the upper half or the
lower half. This is necessary so that the students can see that light rays
arrive from all of the object even when the upper half of the light is
obscured. Students will often think that obscuring the upper half will make
half of the image go away, and they are surprised to see that the image just
gets dimmer.

The source is a light source with many rays.
The object is an arrow and the simulation displays only the principal rays
along with the image.
The beam is a parallel beam of light.

They also have 15 posted problems using the simulations. I don't know if
this helps, but it might be useful in the future.

John M. Clement
Houston, TX