A) \[\left( \frac{2-\sqrt{3}}{\sqrt{3}} \right)R\]
B) \[\left( \sqrt{\frac{5}{3}}-1 \right)R\]
C) \[\left( \sqrt{\frac{4}{3}}-1 \right)R\]
D) \[(\sqrt{2}-1)\,\,R\]
Correct Answer: B
Solution :
| In a body centred lattice this position where the atom of maximum size can be fitted should not be lying on the edge centre as the distance between surfaces of two atoms which are at corners of a cube is very small so will be off the edge so will be at distance of \[\left( \frac{a}{4} \right)\] from edge centre on \[\bot \] bisector of edge of cube. Hence |
| we get \[R+r=\sqrt{\frac{{{a}^{2}}}{u}+\frac{{{a}^{2}}}{16}}=\sqrt{\frac{5{{a}^{2}}}{16}}\] |
| \[=\sqrt{\frac{5}{16}\times \frac{16{{R}^{2}}}{3}}\] so \[r=\left( \sqrt{\frac{5}{3}}-1 \right)R\] |
| \[[4R=\sqrt{3}\,a]\] |
You need to login to perform this action.
You will be redirected in
3 sec
