Physics Help Forum Uncertainties

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 Mar 11th 2017, 01:06 PM #1 Junior Member   Join Date: Mar 2017 Posts: 1 Uncertainties Ok so I have 6 samples and have measured the intensity of light scatterred from 15 particles on each sample for a range of different wavelengths of light. For each sample I averaged the 15 particles so I end up with a graph for each particle of the value of the intensity of light against wavelength. These graphs are then all plotted together so I end up with a single graph of intensity of light against wavelength which is made up of 6 lines, one for each sample. Each line has a peak position and I have taken the peak wavelength for each line and have plotted another graph which is the peak wavelength position against the sample number. My question is, how do I calculate the error for the final graph using standard deviation?
 Mar 12th 2017, 11:15 AM #2 Senior Member     Join Date: Jun 2016 Location: England Posts: 163 unless your 6 samples have a relationship that can be defined relative to each other on a quantifiable axis (rather than just sample number), I cannot see that you can define a single standard deviation for the final graph. However, you can derive standard deviations individually for each sample and then derive the average and the standard deviation of these 6 standard deviations. This will give you a measure of the accuracy and repeatability of your experiment (although 6 samples is a a bit small for deriving a good standard deviation).

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