Re: brightness vrs. power

[David Strasburger-fac <David_Strasburger-fac@NOBLES.EDU>]

PHYS-L@lists.nau.edu writes:
> > Radiant energy depends on temperature of a filament. For instance when
> two
> > similar bulbs are connected in series the net current is (approximately)
> > halved. The power dissipated in both bulbs is reduced by factor 1/4.
>
> I don't know how you calculated this, but it is incorrect. Light bulbs
> do not obey Ohm's law. They are extremely nonlinear.

This may be true, but I saw a demonstration about three summers ago in
which the instructor broke the glass on a household bulb and immersed the
filament in a bath of water with an electric stirrer to keep the
temperature as uniform as possible.  He varied voltage and measured
current -- I have to say the relationship looked awfully linear to me.

David