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Re: Optical pyrometers, was R = V/I ?

Leigh,

What is the "microwave demonstration"?

Of course I would finish with
the microwave demonstration I learned from people in this group. I >do it
for my (university) students whenever I have a party at my >home. It is
always a big hit.




Steven T. Ratliff
Associate Professor of Physics
Northwestern College
3003 Snelling Ave. N.
St. Paul, MN 55113-1598
U. S. A.

Internet: str@nwc.edu (or stratliff@nwc.edu)





Leigh Palmer <palmer@SFU.CA>
Sent by: "phys-l@lists.nau.edu: Forum for Physics Educators" <PHYS-L
05/09/00 06:30 PM
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Subject: Re: Optical pyrometers, was R = V/I ?


I've regarded the problem of the filament area as too hard, so we've
never
calculated a value for the S-B constant. Apart from finding the length
and
thickness of the coiled wire, there is the question of how the coiled
coil
behaves: I imagine it is in part like a hot cavity inside, with not all
of
the surface facing outwards.

It is actually an easy problem. Only the gross outside cylinder matters.
The hard part will be measuring it, a problem we solve by using a long
distance microscope which is included in the optical pyrometer.

I see you have taken a hand lens to the filament before. I consider the
coiled coil to be a major technical triumph of the twentieth century.
Tungsten is, after all, a very refractory, brittle metal. So how can
such an exquisite structure be drawn and shaped from such a metal?

While I don't use light bulbs as examples in Ohm's law demonstrations,
I do devote time to them in lectures. They are wonderful mundane
technology, and I could build an excellent inquiry science module for
elementary schools around light bulbs. Of course I would finish with
the microwave demonstration I learned from people in this group. I do
it for my (university) students whenever I have a party at my home. It
is always a big hit.

Leigh