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Calculating light bulb resistance

Discussion in 'Electrical Engineering' started by Peter, Jan 16, 2007.

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  1. Peter

    Peter Guest

    Is there an equation to calculate the resistance of a light bulb as it
    heats up over time?

    I'd assume this is an intergral formula and is not linear.

  2. Don Kelly

    Don Kelly Guest

    Right - and unfortunately it is somewhat dependent on external conditions
    which may not be present in any lab test because the thermal regime dictates
    the resistance at any time.
    One thing that can be done is to vary the voltage and measure the current
    to get a V-I curve. This still doesn't get you there as then one needs to
    consider external resistance and inductance to try to get a non-linear
    differential equation to give what you want. Even that would be an

    A second thing is to use a scope and get traces of voltage and current on
    energisation of a bulb and from this get the variation of resistance with
    time, for that particular voltage source. Another source, another place,
    another R vs time curve.
  3. Bud--

    Bud-- Guest

    You could try sci.engr.lightning
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