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Diffraction of Light

Problem 5.156

On transmitting a beam of X-rays with wavelength \(\lambda\) \(=17.8 \mathrm{pm}\) through a polycrystalline specimen a system of diffraction rings is produced on a screen located at a distance \(l=15 \mathrm{~cm}\) from the specimen. Determine the radius of the bright ring corresponding to second order of reflection from the system of planes with interplanar distance \(d=155\) pm.

Reveal Answer
5.156.r=ltan⁡2α=3.5 cm, where α is the glancing angle  found from the condition 2dsin⁡α=kλ . \begin{aligned} &5.156 . r=l \tan 2 \alpha=3.5 \mathrm{~cm}, \text { where } \alpha \text { is the glancing angle }\\ &\text { found from the condition } 2 d \sin \alpha=k \lambda \text { . } \end{aligned}
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