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688.


Problem 47.40 (RHK)


Monochromatic x rays fall on a crystal of sodium chloride, making an angle of with the reference line shown in the figure. The interplanar separation is . We have to find the angle through which the crystal must be turned to give a diffracted beam associated with the planes shown. We may assume that the crystal is turned about an axis that is perpendicular to the plane of the page.

Solution:           Click For PDF Version

 Let the Bragg angle for the x rays of wavelength, , to be reflected from the lattice with interplanar separation , be .

Using the Bragg equation, we will find the value of . It is given as follows;

The crystal will have to be rotated clockwise by ,, so that the angle between the incident x rays and the crystal planes is required for Bragg reflection.