# Uncertainty of Grating Constant

1. Oct 30, 2005

### jdog6

All right, I have to calculate the uncertainty of the grating constant (k=1/d).

I know that the standard deviation of my 14 values of d(spacing bewtween 2 slits in a diffraction grating) is ± 5.031x10-16 m.

Average d = 3.403x10-6m .
k= 2.939x105lines/m.
How would I find uncertainty? 1/± 5.031x10-16 m?

Im really stuck here, please help.
Thank you.

2. Oct 30, 2005

### big man

Well since you have 14 measurements of 'd', and those measurements yield a standard deviation of ± 5.031x10-16 m, your error in d will be the standard error. That is, your standard deviation divided by the square root of the number of measurements.
If this is an introductory course then$$\Delta$$K = K*($$\Delta R/R$$) would suffice as the uncertainty in your value of K.

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