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    Question: Calculate the uncertainty in the resistance of a bulb. The equation is R=V/I and the following measurements were taken:
    Potential Difference = 1.1 V
    Current = 0.4 A
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    (Original post by XtrJ)
    Question: Calculate the uncertainty in the resistance of a bulb. The equation is R=V/I and the following measurements were taken:
    Potential Difference = 1.1 V
    Current = 0.4 A
    This question is checking whether you understand the connection between uncertainty and the number of significant figures used.

    1.1 V has 2sf
    0.4 A has 1 sf - so it could be anywhere between 0.350 and 0.449

    trailing zeros AFTER the decimal point *are significant figures* - if you measured the current to higher precision you could write 0.40 (i.e. 2sf) which would mean it was between 0.395 and 0.404

    the rules for combining uncertainties at A level are in stonebridge's sticky http://www.thestudentroom.co.uk/show....php?t=2661762
 
 
 
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