in the early 60s at the GE Research Lab in Schenectady, NY there was a
display in the main lobby that answers the question. Burning there was an
Edison lightbulb, not very brightly, but burning nonetheless. It would not
be surprising to find that said bilb is still on display giving off a meager
amount of light.
E.C. Muehleisen
Too much of a good thing is wonderful!
From: "Larry Woolf" <larry.woolf@ga.com>
Reply-To: Forum for Physics Educators <phys-l@carnot.physics.buffalo.edu>
To: "Forum for Physics Educators" <phys-l@carnot.physics.buffalo.edu>
Subject: Re: [Phys-l] 50 year incandescent bulb
Date: Tue, 1 May 2007 20:35:15 -0700
MIME-Version: 1.0
Received: from carnot.physics.buffalo.edu ([128.205.17.137]) by
bay0-mc11-f9.bay0.hotmail.com with Microsoft SMTPSVC(6.0.3790.2668); Tue, 1
May 2007 20:36:59 -0700
Received: from localhost (localhost [127.0.0.1])by
carnot.physics.buffalo.edu (Postfix) with ESMTP id 2D8012C555;Tue, 1 May
2007 23:36:59 -0400 (EDT)
Received: from carnot.physics.buffalo.edu ([127.0.0.1]) by localhost
(carnot.physics.buffalo.edu [127.0.0.1]) (amavisd-new, port 10024) with
ESMTP id 28732-09-3; Tue, 1 May 2007 23:36:57 -0400 (EDT)
Received: from carnot.physics.buffalo.edu (localhost [127.0.0.1])by
carnot.physics.buffalo.edu (Postfix) with ESMTP id 882CE2C565;Tue, 1 May
2007 23:36:00 -0400 (EDT)
Received: from localhost (localhost [127.0.0.1])by
carnot.physics.buffalo.edu (Postfix) with ESMTP id 54E852C555for
<phys-l@carnot.physics.buffalo.edu>;Tue, 1 May 2007 23:35:56 -0400 (EDT)
Received: from carnot.physics.buffalo.edu ([127.0.0.1])by localhost
(carnot.physics.buffalo.edu [127.0.0.1]) (amavisd-new,port 10024)with ESMTP
id 28736-12 for <phys-l@carnot.physics.buffalo.edu>;Tue, 1 May 2007
23:35:45 -0400 (EDT)
Received: from VEX.ad.ga.com (unknown [141.248.128.83])by
carnot.physics.buffalo.edu (Postfix) with ESMTP id 18BEB2BD10for
<phys-l@carnot.physics.buffalo.edu>;Tue, 1 May 2007 23:35:44 -0400 (EDT)
X-Message-Info:
oG9qAjD2BNERpLPeNOdF2M+pWysHYwDWpm2rFzmjlCTuF/NDSfS71dslxaUqYrkV
X-Original-To: phys-l@carnot.physics.buffalo.edu
Delivered-To: phys-l@carnot.physics.buffalo.edu
Content-class: urn:content-classes:message
X-MimeOLE: Produced By Microsoft Exchange V6.5
X-MS-Has-Attach:
X-MS-TNEF-Correlator:
<C98182820321A14683900A685467B92102357D4D@VEX.ad.ga.com>
Thread-Topic: [Phys-l] 50 year incandescent bulb
Thread-Index: AceMGIEY3K8RB4/oQByIwLtTgXxVQgAUYhb9
References:
<4636CD7C.3050401@redshift.com><p06110409c25d1ebf8d42@[144.17.10.100]><6.1.2.0.0.20070501101240.01fc8ec0@alf.deskmail.washington.edu><a06240508c25d2bc5de99@[192.168.1.100]>
X-Virus-Scanned: amavisd-new at physics.buffalo.edu
X-Content-Filtered-By: Mailman/MimeDel 2.1.7
X-BeenThere: phys-l@carnot.physics.buffalo.edu
X-Mailman-Version: 2.1.7
Precedence: list
List-Id: Forum for Physics Educators <phys-l.carnot.physics.buffalo.edu>
List-Unsubscribe:
<https://carnot.physics.buffalo.edu/mailman/listinfo/phys-l>,
<mailto:phys-l-request@carnot.physics.buffalo.edu?subject=unsubscribe>
List-Archive: <https://carnot.physics.buffalo.edu/archives>
List-Post: <mailto:phys-l@carnot.physics.buffalo.edu>
List-Help: <mailto:phys-l-request@carnot.physics.buffalo.edu?subject=help>
List-Subscribe:
<https://carnot.physics.buffalo.edu/mailman/listinfo/phys-l>,
<mailto:phys-l-request@carnot.physics.buffalo.edu?subject=subscribe>
Errors-To: phys-l-bounces@carnot.physics.buffalo.edu
X-Virus-Scanned: amavisd-new at physics.buffalo.edu
Return-Path: phys-l-bounces@carnot.physics.buffalo.edu
X-OriginalArrivalTime: 02 May 2007 03:37:00.0245 (UTC)
FILETIME=[24577850:01C78C6B]
At 10:21 AM -0700 on 5/1/07, Jason Alferness wrote
>But then, I'm still a little confused why they can't design a 50 year
incandescent bulb...
Chuck Britton replied:
My (limited) understanding is that a 50 incandescent bulb could be
designed - but it would not give off as much light as you would
expect.
I notice that (some?) 'long life' incandescent bulbs are 'rated' at
130 volts rather than the more common 120 volts.
I.e. the filament is cooler when it is used at 120 volts and is
putting out less than the rated wattage (wattage rated at 130 volts
=> longer life due to 120 volt use)
============================================
Bulb lifetimes are limited by evaporation of the tungsten filament. At
lower filament temperatures, the vaporization rate of the tungsten filament
is reduced, but so is the light output. So the filament temperature is a
compromise between light output and lifetime.