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Re: Test Writing



Howdy-

From: Herbert H Gottlieb [mailto:herbgottlieb@JUNO.COM]
Sent: Tuesday, April 30, 2002 2:13 PM

*** Have you tried this? I doubt your claim that the drawings will
all look nearly the same.

Uhmm. Yeah, I have. Are you talking about the difference in perspective or
angle? Those are different, but the content of the image is the same.
Perhaps I should have better worded the question, although I have never had
a student make that objection.

*** Do you mean that only one of the persons is looking
through the magnifying glass? If both are looking
through the same glass, at the same time, with
their heads fairly close together why would
their pictures look different?

Both are looking through the magnifying glass. Even with a relatively small
displacement of the eye, differences in the content of the image are
evident.

The screen is an important element to the solution and the fact that only a
real image can be projected on a screen.

*** If only real images appear on the retina, how is it possible that
we can see a virtual image .... for example... a plane mirror porduces
a virtual image/ How are you able to see such an image when you
are shaving or applying lipstick?

Despite being a vampire, I do see my image in the mirror. I trace the rays
leaving my face and show them hitting the mirror, following the laws of
reflection and then some of them hitting the lens of my eye where they make
a real image on my retina. I see no reason to trace these lines backwards
into mirror land and create a fictious originating point. I know where they
orginated, on my face.

The problems work just the same.

Software can take all the tedium out of the approach. A program called Ray
Trace will do it all.

Marc "Zeke" Kossover