Light bulb current-voltage characteristics

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someonesdad

Joined Jul 7, 2009
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I was looking for something else and came across these measurements I did a few years ago. The instruments weren't in calibration (and still aren't), but I trust them within a few percent.

The fitted model might be useful to those who want to estimate the resistance of an incandescent lamp at a certain current. Some day I'll also measure the usual 60, 75, and 100 W bulbs laying around the house. They can make useful (albeit nonlinear) dummy loads.

I did the spreadsheet in Open Office. It has a nice feature in the graph -- you can click on the graph line and tell it to fit a curve to it via linear regression and to put the equation and correlation coefficient on the graph. I haven't used Excel in years; you could do linear regression in Excel, but it was more of a pain if I remember correctly. The curves available to fit are linear, log, exponential, and power. This plot looked about like a square root to me, so I picked power.
 

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