Re: lightbulbs

["Daniel L. MacIsaac" <Dan.MacIsaac@NAU.EDU>]

Yvone:

If you have adobe acrobat, download and check out
http://pc53.phy.nau.edu/danmac/filament/full_doc.pdf

which discusses an experiment related to the problem you are ahving here.

Regards,

Dan M

Dan MacIsaac, Assistant Professor of Physics and Astronomy, Northern AZ Univ
danmac@nau.edu          http://purcell.phy.nau.edu         PHYS-L list owner

> Here's a simple experiment I'm having trouble with.  Our grade 9 science text suggests experimenting with different voltage miniature screw ligntbulbs operated at the same voltage.  The purpose is to find the relationship between the resistance of the bulb and the illumination produced by the bulb.
>
> I tried 3 bulbs (1.5 V, 3.8 V, 6V) sequentially wired to the same  1.5 V drycell.
> The least light is obtained with the 6 V bulb and the most light with the 1.5 V bulb, as I would have anticipated.  But here is where it gets complicated. I would expect that the greatest the voltage rating of the bulb, the highest would be its resistance and lowest its current.
> The current and resistance values were obtained with a digital multimeter.  Here are the results:
> 1.5 V bulb        3.8 V bulb        6 V bulb
> 1.6 ohms        2.9 ohms            1 ohm
> 0.22 A            0.18 A                0.28 A
>
> The results were consistant with different bulbs from the same batch, and were triple verified.  Please enlighten...