% uncertainty

[Roden]

How do i calculate the % uncertainty for example of a Voltmetre

I have a set of results for resistance in a wire, and the voltage alters from 1.17v to 1.47v

Do i need to work out the % uncertaincy for both results and then do something with the 2 answers or just pick a number and then do it, because obviuosly using different valuesfrom my set of results will affect my % uncertainty.

thanks roden

[Roden]

also i forgot to add the accuracy of the voltmeter is �0.01V

[heathfield]

Look here under the section headed 'Relation...', second paragraph down.

[topogigo]

If i am not mistaken, the mean of all readings is your zero line, how much your highest and lowest readings differ from this are then used to calculate a second "mean"(You could consider the accuracy of the voltmeter at this point also, make a third "mean" and reduce that and the second to a fourth to replace the second and third) The percentage of readings that are different to the first mean by the magnitude of the fourth, or third had you not considered the accuracy factor,give a measure of the uncertainty.