Aren't the ratings for the fully illuminated state? The filament resistance seems like it'd be hugely temperature dependent.
jg
--
Joshua Gates
Physics Faculty
Tatnall School (Wilmington DE)
JHU Center for Talented Youth
_____
From: Anthony Lapinski [mailto:Anthony_Lapinski@pds.org]
To: tap-l@lists.ncsu.edu, phys-l@carnot.physics.buffalo.edu
Sent: Tue, 08 Mar 2011 08:06:24 -0500
Subject: [Phys-l] light bulbs
I have some incandescent bulbs from Europe. In America, the voltage is
half as much, so the current is half as much. Thus, the power should be
one quarter as much (P = IV)
A 60-W European bulb should behave like a 15-W American bulb (4X less
power). However, when I plug it in, it looks more like the glowing
filament of a 7.5-W bulb (8X less power). So I am a bit puzzled with this.
I am wondering if it has something to do with the filament specs. I
believe the electrical frequency in Europe is 50 Hz, but that shouldn't
really matter with 60 Hz in the US.
Anyone have experience with this, or a similar demo?