Crystal frames problem, what actually asking?

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frostysh
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Homework Statement



The problem from Sterway, Jewett book.

Text problem 7 with a diagram of cubes of side L = 0.200 nm stacked in a lattice, showing a crystal cleaving along a face diagonal, with the spacing d between adjacent planes asked for.


Two-part diagram of a close-packed crystal lattice of spheres in a rectangular block with a diagonal plane; part a shows length L and diagonal d, part b shows cut faces of the block.


The Attempt at a Solution



The answer in the book is something like 0,141 nm, as I remembered but I cannot achieve such answer coz' I cannot understand what actually asking, d is looks like a distance between two centers of the atomic spheres, but I don't think that it can be 0,141 nm, probably due to my English language, so can somebody clarify for little bit, what the hell I need to find in this problem. I am stucked for now, and my brain will start to melt soon. And imho - this book have too much of unnecessary problem, 70 problem for the first chapter is too much... Thanx.
 
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In the same way as the distance between vertical or horizontal planes is L, the distance between the 45 degree planes is ##{1\over 2}\sqrt 2 ## L. Easiest seen in a side view:
Diagram of a 3 by 4 grid of touching circles with three dashed red diagonal lines running at 45 degrees across the grid.
 
BvU said:
In the same way as the distance between vertical or horizontal planes is L, the distance between the 45 degree planes is ##{1\over 2}\sqrt 2 ## L. Easiest seen in a side view:
View attachment 198771
Or this picture in the book is distracting, or frostysh is just too dull :), anyway I have solved the problem on my new cool self-made school-board, and now I am very happy ^^. Thanx again, Solved.