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Percentage uncertainty

So, I have an experiment in which I have to measure the resistance per metre of a wire. I am using a voltmeter-ammeter method to do this, by measuring the changes in voltage at different points on the wire (keeping the current the same, through the use of a variable resistor).

Now, I'm just wondering, say if I took two readings for voltage, one where the length of wire was 0.2m, and one where the length was 0.8m, when I calculate resistance per metre using R= V/(I x L), which would have a higher percentage uncertainty and why?

Thanks :smile:




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% uncertainty is a %age of the value you measure.
So if the actual (absolute) uncertainty is the same in both readings, then the % uncertainty will be smaller in the larger reading.

%uncertainty = 100 x (uncertainty/reading)

If the reading is greater then...
Reply 2
Original post by Stonebridge
% uncertainty is a %age of the value you measure.
So if the actual (absolute) uncertainty is the same in both readings, then the % uncertainty will be smaller in the larger reading.

%uncertainty = 100 x (uncertainty/reading)

If the reading is greater then...


Thank you so much :smile: :smile: :smile:


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