Calculating Experimental Error of Braggs Equation

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SUMMARY

The discussion focuses on calculating experimental error using Bragg's Law in X-ray diffraction experiments. The primary equation under consideration is D = A/sin(x), where D represents the spacing between atoms, A is a constant, and x is the angle of maximum intensity. Participants emphasize the importance of error propagation techniques, specifically the derivative of 1/sin(x), to accurately determine the error in D based on the error in x. The conversation highlights the need for clarity in measuring the angle x to ensure precise calculations.

PREREQUISITES
  • Understanding of Bragg's Law in X-ray diffraction
  • Familiarity with error propagation techniques
  • Knowledge of calculus, specifically derivatives
  • Basic concepts of angle measurement in experimental physics
NEXT STEPS
  • Study error propagation methods in single-variable functions
  • Learn how to differentiate trigonometric functions, particularly 1/sin(x)
  • Explore advanced applications of Bragg's Law in crystallography
  • Review techniques for accurately measuring angles in X-ray diffraction experiments
USEFUL FOR

This discussion is beneficial for physics students, laboratory researchers, and anyone involved in X-ray diffraction analysis or experimental error calculation.

Lemenks
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Homework Statement



I am writing a lab report for an X-ray diffraction. I have been attempting to come up with an equation for the error using formulas some people from college gave me and also some I found on wikipedia but I am quite sure I am doing it wrong. The only variable is the angle where the maximum intensities are found. I am using Bragg's law to calculate the spacing between the atoms.

Homework Equations



D = (N*wavelength)/(2*sin(x))

As there is no error in N, wavelength, or "2", we can let that equal A.

D = A/sin(x)

Some equations I was given:

Z = aX
dZ = adX

Z = X^a
dZ/z = |a|dx/x

Z = SinX
dZ = dX CosX

The Attempt at a Solution



D = Z = A/sin(x) = A (sin(x))^-1 = A f(y)^-1

I have tried loads of ways of calculating this but I keep getting silly answers. Any help, ideas or links would be really appreciated.
 
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Hello Lemenks, and welcome to PF :)

I don't see an attempt at solution under 3, only a repeat of D=A/sin(x).

From your account, I think what you are asking is: What is the error in D = A/sin(x), given the error in x. Correct ?

Your relevant equations are some examples of error propagation in functions of a single variable. Generally: ##df = {df\over dx} dx##, which in error analysis is extended to finite differences: ##\Delta f = {df\over dx} \Delta x##.
Do you know how to find the derivative of 1/sin(x) ?

And I am interested in the way you determine ##\Delta x## too. Is it really just a simple reading off of a single angle ?
 

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