Re: Comic books as classroom resource

[Ivan Rouse <irouse@LASIERRA.EDU>]

At 03:18 PM 5/14/02 -0700, you wrote:

> On Mon, 13 May 2002 11:09:37 -0500 "Dr. Paul O. Johnson"
> <pjohnson@SCIENCEPLACE.ORG> writes:
> > Do you remember the Peanuts strip several; years ago in which Snoopy
> > is  lying prone on his roof looking down into his dish. He says
> "Objects
> > under  water always look deeper." This confused the hell out of my
> students
> > when I  tried to correct it.
> >
> > poj
>
> I have been having trouble with this one.  When I try to retrieve the
> soap
> at the bottom of my bathtub full of water, the soap ALWAYS appears to
> CLOSER to the surface than it really is.  That is... the water appears to
> be
> LESS DEEP than it really is..

Herb,
Here is a way to think about it:
1.      Think of some rays of light coming up from the soap to the surface.
2.      When the rays go from a higher index medium (n water=1.33) to air
(n=1) the rays will bend away from the normal.
3.      Now extrapolate those rays back to see where they "appear" to come
together.  That is where the virtual image will be.  It should be closer to
the surface than the actual depth of the soap just as you had
experienced.  This means that the Snoopy cartoon is wrong so it makes a
really good cartoon to have the students analyze.

> Please clarify.
> Thanks
>
> Herb
>
>
>
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Ivan Rouse, Physics Professor
Physics Department, La Sierra University
4700 Pierce St., Riverside, CA 92515
email: irouse@lasierra.edu
phone: 909-785-2137, FAX 909-785-2215