- #1

frederer

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## Homework Statement

You wish to study a material with a cubic crystal structure with

three orthogonal sides of length a = 0.3nm. What is the

longest possible wavelength of the X-ray source you could use

to reveal the (211) Bragg peak of the crystal?

## Homework Equations

nλ = 2dSinθ (Bragg's Law)

d = a/sqrt(h^2 + k^2 + l^2)

## The Attempt at a Solution

Hi. Ok so i think i need the two formulae above to solve this question.

You can figure out d simply enough by slotting in the numbers,

giving λ = 2.44Asinθ

but the trouble I am having is how to calculate the angle θ. If you draw out the

cube in question you can see the angles formed between in the plane but

I am not sure which angle, if one of these angles at all is required to solve

the question. Any help would be much appreciated.