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Homework Help: Resistance-current characteristic in the case of filament lamp (investigation)

  1. Feb 8, 2012 #1
    Changing voltage - independent variable
    current flowing - independent variable
    The investigation was aimed at measuring current at different potential differences, before the filament lamp started to shine and when it was shining so as to observe both ohmic and non-ohmic behaviour. Also after calculating the resistance, the characterisitc
    between it and current was to be analyzed.
    Anyway, the ammeter, voltmeter, filament lamp, wires and clips were used.

    Hence, my question is arising, do you have any ideas (except internal resistances), what could cause occuring of some errors (systematic or random) and how it could be improved ?
  2. jcsd
  3. Feb 8, 2012 #2


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    Homework Helper

    Hi eida,

    Internal resistances cause the main problem.
    Make a circuit diagram, show how would you connect the voltmeter and ammeter to the lamp. Remember, the ammeters have internal resistance of several ohms, comparable to the resistance of the filament. You can check it. At the same time, the internal resistance of the voltmeter is high compared to the filament. It is important that you measure the voltage across the lamp, so connect the voltmeter directly to the terminals of the lamp. I would like to see the measuring arrangement.

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