Re: Bending of Ohm's Law was Re: Gap Question

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Original poster: dave pierson <davep-at-quik-dot-com> 


>Awesome!!
>Any idea where I could find a V I curve chart for a standard light bulb?

    Its a straight line.  A resistance.
    (pause...)

    AT ANY ONE TEMPERATURE.
       (To fully plot it, or any, needs a 3D graph...
        with temp on the other axis...)

    (arc/spark has negative resistance at constant temp...)


    Resistance of almost anything varies with
    temperature.

    Lightbulbs (filaments) get VERY HOT, so the change is noticeable.


>Does not have to have exceptional detail but would like a graph with
>actual voltages and currents labeled on it along with the general shape
>of the curve.

    cf as above.
    General rule of thumb is that the fixed resistance at room temp is
    1/10th  that at 'normal (operating) temperature.

    (Yes: this means a lightbulb of say 100W/1A/110v (I'M ROUNDING  8)>>)
    draws. momentarily, 10A when first switched on...)

    For experiments a 'microlight' type holiday bulb
    (or several) and an old style, moving coil VOM are
    instructive:  such a meter can deliver up to an amp or
    so, which lights the lamp, which increase the resistance.).

    Ohm's Law is a law, as derived FOR WIRES.
    It DOES NOT apply to 'all conductors'.
    8)>>

    best
     dwp