Need confirmation on lightbulb experiment

AI Thread Summary
The discussion centers on an experiment involving a light bulb's resistance and its relationship with battery voltage. The equation y = 0.08x + 0.14 was derived to represent the amp draw through the bulb based on the number of batteries used. Initial measurements indicated a resistance of 1.3 ohms, while calculations suggested a resistance of approximately 11.47 ohms at 5.16 volts, leading to an amp draw of about 0.45A. The main inquiry is whether a linear model can be used to determine the bulb's resistance for each individual cell and how to construct such a model. A referenced link provides additional insights into the non-linear behavior of the bulb, indicating that it cannot be accurately modeled with a simple linear equation over the tested voltage range.
Flyingwing12
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I was piddling with my meter and graphing calculator and came up with this equation

y= .08x+.14

This equation uses the number of batteries for X, and the Amp draw through a light bulb for Y.

The results are theoretical past 4 batteries.

The batteries were 1.29 v when the experiment began.

The real question here is about resistance.

Outside here it is about 80 degrees F, the ohmmeter showed 1.3 ohms from the light-bulb. The light bulb, using Ohms law, will have a resistance of ~11.4667 ohms when ~5.16 V are put to it. Meaning an amp draw of ~.45A

*With this initial resistance and final resistance being known, can I use a linear model to find the resistance of the bulb for each individual cell?*

How would this model be constructed?

If a graph were to be constructed it would start at (0,1.3) and end at (4, 11.46667). Is there any digital way of finding the missing values?

Kind of a math question isn't it?
 
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Engineering news on Phys.org
See part 2 in this link. It describes exactly your experiment, even uses your method of force voltage with batteries, and how to plot out the v vs i curve and what not.

http://teachers.usd497.org/agleue/unit_pdfs/electricity_unit_1/electricity_unit_1_ohm_laws_and_light_bulb_lab.pdf
 
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btw, i found this via a google when looking for the v vs i of a light bulb over this voltage range. here the bulb's large signal behavior isn't ohmic so it can't be modeled accurately over this range with an equation of the form y=mx+b.

you'll see all that, and an explanation, in the results section of the link above.
 
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