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About a year ago Professor Debora M. Katz of Annapolis Physics
Dept. signed the guestbook, and after some e-mails I sent her
a 30W Shelby Bulb, the same vintage and make as our Centennial
Bulb. The reason was she has the facilities to test the bulb
in ways we could never attempt with big brother.
I put a few questions to her about filament size, (to dispell
the myth of it being pencil thickness), the actual heat by means
of a temperature coeeficient test, and an analysis of the 100
year old gases inside.
2008
Dr. Katz had this to say about the results;
"I
found the width of the filament. I compared it to the width of
a modern bulb's filament. It turns out that a modern bulb's filament
is a coil, of about .08 mm diameter, made up of a coiled wire
about 01 mm thick. I didn't know that until I looked under a
microscope. The width of the Shelby bulb's 100 year old filament
is about the same as the width of the coiled modern bulb's filament,
.08 mm.
We didn’t want to break the Shelby
bulb so we used the laser."
For comparrison the thickness of a human hair is approximately
0.06-0.09 mm.
Below are some pictures of the experiment using the laser.
When asked if the thickness could attribute to the longevity
she replied,
"I don't have a clear answer.
I think the thickness may make a difference. I wonder if the
filament does not get as hot. I think I would like to see if
I can get the spectrum."
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Thank you Professor Katz, for your time and skills
in answering our puzzling questions. We look forward to your
next tests!
(Please click thumbnails to enlarge) |
2010
In 2010 Dr. Katz assigned a grad student, Ensign Justin Felgar,
to continue with the tests, and he wrote a great paper on Shelby
bulbs. Please follow this link to his published paper, in pdf form. He included
a lot of historical research as well as results from his tests
on the 30W bulb. Fantastic! |
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