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"1. You cannot always see a real image. The real images that aresee
formed by a convex lens or a concave mirror are usually invisible. To
such an image it is necessary to place a screen at the position that the
image forms . If a screen is not placed at the image position , theimage
is still formed there .... but it is invisible."
Please give me a specific example (excluding those which cannot be
seen because ones head is in the way -- off axis and a diagonal mirror
will? solve that problem.) of an invisible real image.
"2. You can see a virtual image. Just .........."
I think this is an analytic statement
bc
Herbert H Gottlieb wrote:
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On Tue, 30 Apr 2002 07:53:03 -0500 Tina Fanettihas
<FanettT@QUEST.WITCC.CC.IA.US> writes:
I would prefer not to give multiple choice tests, however, there
between a real and a virtual image.been some friction over the essay/short-answer questions.
Example:
On the last test I asked students to explain the difference
fully correct.
Student answered: You can see a real image. You can't see a
virtual image. I took off points for this because it is not
reasons:
****************************************
Perhaps Tina should have taken of more points for the student's
answer because his answer was absolutely wrong for the following
formed
1. You cannot always see a real image. The real images that are
byan
a convex lens or a concave mirror are usually invisible. To see such
image it is necessary to place a screen at the position that theimage
forms . If a screen is not placed at the image position , theimage is
there
still formed there .... but it is invisible.
2. You can see a virtual image. Just look into a plane mirror and
it is!images)
Herb Gottlieb from New York City
( Where we can see virtual images but cannot always see real
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