Lew Hodgett wrote:
"FrozenNorth" wrote:

Correct the bulbs resistance is fixed, increased voltage causes more
amperage, reduced voltage reduces the amperage. Light output and
bulb life will vary according to their ratings.
==============================================
NOT!!!

As the voltage rating of a specific wattage lamp rating increases, so
does the
resistance of the filament.

This increased filament resistance provides a mechanically heavier
wire which
then allows for a "rough service" or "traffic signal" lamp rating.

The increased filament resistance also reduces the current flowing
thru the filament
which in turn reduces the lumen output.

Basic data available in any lamp catalog.

Just some of the basic engineering trade offs the lamp designer faces.



Lew




Please explain *CLEARLY* how increasing the thickness of any uniform
substance can *increase* the resistance if everything else remains
unchanged.

Hint: imagine a square wire of a fixed length, double its thickness and
width, now explain to me the difference between that and four wires of
the original thickness in parallel for 1/4 the resistance!

--
Ian Malcolm. London, ENGLAND. (NEWSGROUP REPLY PREFERRED)
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