On Fri, 7 Jan 1994, Roland Dudley wrote:
>
> Isn't the power rating (wattage) of a light (whether incandescent,
> fluorescent, halogen, or whatever) the power it consumes? So a 40w
> fluorescent light is brighter than a 40w incandescent bulb because it
> converts more of its input electrical energy to light energy, even
> though they both consume power at the same rate. i.e., less electrical
> energy is converted to heat energy by the fluorescent lamp. Or maybe
> I'm missing something.
>
> Roland
Lord. Now I've stepped in it. Yes, that's what I meant to say though it
may not have been very clear. Two 20 w fluorescents together provide more
light than a single 40 w incandescent, while consuming the same power,
because a larger percentage of the power is converted to light. And it
also follows, I think, that they produce less heat *under most practical
circumstances*. The part I cannot answer is how much less the heat is.
Light from bulbs gets absorbed by things, and heating them up. If we
surround a 40W fluorescent light with an opaque black box, and also
surround a 40W incandescent bulb with a black box, I doubt anyone could
tell, by the temp of the box, what kind of bulb was inside. 40 watts goes
into each, and ends up entirely as heat.
In the tail lights, one of the things that gets warmed up by filament heat
and light absorption is the red tail light lenses we are worried about.
What we want is for more light to escape down the road and warm up the
eyeballs of the driver behind. In the end, I just don't know how much the
heat would be reduced and how much the light would increase if one
were to install higher efficiency bulbs with the same wattage. It might
depend largely on how dark your lenses are.
I am a far better experimentalist than I am a theoretician. But I feel
secure in saying that replacing a 32W conventional bulb with a 55W halogen
bulb will definitely increase the current, definitely make the lights
brighter, and very likely bring the tail light lenses closer to the
melting point.
To really get beyond where I feel secure, I will go ahead and say that I
doubt that the difference between halogen and conventional bulbs is
anything like as great as the difference between fluorescent and
conventional bulbs. Very possibly, any greater efficiency of halogen may
come from running the filament at a higher temperature than in a
conventional bulb, with the oxidation of the filament that would happen in
a conventional bulb being reduced by use of halogen gas in the bulb. I
think also there is less tendency for the filament to deposit on the
inside of the bulb, thus reducing light emission. I am not sure why
quartz is used, but it may have something to do with the absorption of
ultraviolet by glass. Somebody on the list has to know more about this
than I; I wish I had kept my mouth shut.
Bottom line: to be really safe, it would be best to replace conventional
tail light bulbs with halogen bulbs of nearly the same wattage. This has
gotta work, though you may not improve the brightness much. If you
increase the wattage, you definitely will get brighter lights (you would
even if you used higher wattage conventional bulbs), but you may melt
something. If in doubt, get a couple of thermometers, put a halogen bulb
in one light, and compare the halogen with the conventional. Or move to
Vermont, where it is presently -4F, destined to get even colder, and you
could not melt your tail light lenses with a blowtorch.
Now, how many angels can fit on the head of a pin? No fair getting a pin
and a bunch of angels.
Ray (I'm going home now; please don't cheer) Gibbons
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