Interesting non-linear effects
bbruhns at erols.com
Sat Nov 10 10:40:56 CST 2012
Looking at the chart in 'Light Bulbs.pdf', the Philips 100W 120V DuraMax
bulb seems to display a negative temperature coefficient of resistance
around 115V to 120V. I didn't see this in the other bulbs that were
listed. The magnitude of the effect is relatively small, and it reminds
me of unexpected things that I see in many such seemingly simple
The dip at 120.8V is probably the result of a measurement recording or
transcribing error - if someone thought the notes said 0.89A when they
really said 0.84A, then the resistance calculation would have shown 144
instead of 136, and the graph would have been much more believable.
(See attached spreadsheet.) But maybe 0.89A was the correct reading,
and the dip at 120.8V was real. I sometimes wonder how much information
is routinely ignored in day to day work.
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