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Re: Virtual and Real Images



At 0:47 -0600 3/20/02, John Clement wrote:

The floating coin is a real image. When you look at the floating coin it is
in front of the mirror. This means that the light is actually coming from
the location of the image. The light rays actually cross there, so it is
must be a real image. Virtual images do not have the light rays cross, so
they must be behind the optical system. The light rays only appear to have
come from a virtual image. You can also see the real image in front of a
convex lens if you hold the lens at arms length. Normally real images are
inverted, but because the image is produced by 2 consecutive mirrors, the
image appears right side up. Note that applying the definition of real and
virtual in terms of ray crossing requires formal thinking, and can be
tricky. However a simple rule like virtual images are behind the optical
system and are not inverted brings the idea down to the concrete level. The
in front/behind rule is also not easily used, as most students can not
really tell where the image is actually located by just looking at it. This
latter skill requires some time to develop.

Makes sense to me. I stand corrected.

Hugh
--

Hugh Haskell
<mailto://haskell@ncssm.edu>
<mailto://hhaskell@mindspring.com>

(919) 467-7610

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